MOBILE VIEW  | 

PLANTS-ALLIUM SPECIES

Classification   |    Detailed evidence-based information

Therapeutic Toxic Class

    A) Garlic (Allium sativum) is an herbal plant with both culinary and medical actions. It is not known to be toxic when used for culinary purposes.

Specific Substances

    A) ALLIUM SATIVUM (L.)
    1) Ajo
    2) Allium controversum
    3) Camphor of the Poor
    4) Garlic
    5) Nectar of the Gods
    6) Rustic Treacle
    7) Stinking Rose
    8) Taisan (crude drug name for garlic)
    9) Allium species-Plants
    10) CAS 8008-99-9 (extract)
    ALLIUM CEPA
    1) Commercial onion
    2) Onion
    ALLIUM CANADENSE
    1) Tree Onion
    2) Wild garlic
    3) Wild onion
    ALLIUM SCHOENOPRASUM
    1) Chives

Available Forms Sources

    A) FORMS
    1) The fresh garlic cloves have 0.1% to 0.3% of volatile oil (Reynolds, 1982), which is brown-yellow in color, has a disagreeable odor, and consists primarily of allyl disulfide and allyl propyl disulfide with small amounts of higher polysulfides (Okuyama et al, 1989).
    2) Garlic is available in a variety of commercially processed condiments, typically garlic powder and garlic salt. The sodium content in garlic salt varies among manufacturers; some examples are listed below:
    1) Schilling/McCormick's garlic salt: 1895 mg sodium/tsp
    2) Lawry's garlic salt: 968 mg sodium/tsp
    3) Spice Island garlic salt: 930 mg sodium/tsp
    B) USES
    1) Garlic has been used in folk medicine since ancient Egypt and has had numerous herbal uses including alleged cure of leprosy, clotting disorders, deafness, earaches, scurvy, and flatulence, and as a disinfectant, antidote, anthelminthic, and cure for arteriosclerosis and gastroenteritis (Anon, 1994; Hikino et al, 1986).
    2) Garlic (Allium sativum) is not known to be toxic when used for culinary purposes (Anon, 1994).

Life Support

    A) This overview assumes that basic life support measures have been instituted.

Clinical Effects

    0.2.1) SUMMARY OF EXPOSURE
    A) DESCRIPTION: A perennial plant with a bulbous base and erect, 2 to 3 foot tall stem. The bulb has a familiar "garlic" odor. Flowers are pink or purple and bloom from July to September in the Northern Hemisphere. USES: Garlic has been used in folk medicine since ancient Egypt and has had numerous herbal uses including alleged cure of leprosy, clotting disorders, deafness, earaches, scurvy, and flatulence, and as a disinfectant, antidote, anthelminthic, and cure for arteriosclerosis and gastroenteritis.
    B) COMPOSITION: Fresh garlic cloves have 0.1% to 0.3% of volatile oil, which is brown-yellow in color, and has a disagreeable odor. It consists primarily of allyl disulfide and allyl propyl disulfide with small amounts of higher polysulfides. EPIDEMIOLOGY: In general, garlic has not been shown to be toxic when used for culinary purposes.
    C) TOXICITY: The bulbs, bulblets, flowers and stems of the allium species (Allium canadense; wild garlic or wild onion) can produce toxicity if ingested in large quantities. However, plants grown commercially and consumed in smaller amounts do not usually produce adverse effects or illness.
    D) WITH POISONING/EXPOSURE
    1) ORAL: Ingestion of significant amounts may cause gastroenteritis (including nausea, vomiting, abdominal cramping and diarrhea) and hypoglycemia.
    2) OCULAR: Eye exposure may cause tearing.
    3) DERMAL: Skin contact may produce dermatitis and blistering following exposure. Dermal injury has also developed infrequently following prolonged contact with garlic cloves (eg, used as a poultice).
    4) GARLIC SUPPLEMENTS: Patients that ingest garlic tablets or herbal preparations containing garlic in large amounts may be at risk to develop bleeding secondary to potential inhibition of platelet aggregation.
    5) INHALATION: Inhalation of dust may produce asthmatic reactions following occupational exposure. CHRONIC: Iodine uptake may be reduced by chronic garlic ingestion
    0.2.4) HEENT
    A) Garlic vapors or eye contact with the clove oil may cause tearing.
    0.2.6) RESPIRATORY
    A) Allergic reactions have occurred after multiple exposures to garlic dust.
    0.2.7) NEUROLOGIC
    A) Dizziness, sweating, and lightheadedness were noted after a single 25 mL dose of garlic extract.
    0.2.8) GASTROINTESTINAL
    A) A burning sensation of the mouth, stomach, and esophagus may develop after ingestion of garlic. Gastrointestinal upset is a common symptom of significant garlic ingestion.
    0.2.9) HEPATIC
    A) Chronic treatment with the garlic extract, in rats, for 2 months produced reductions in liver protein. The clinical significance of this is unknown.
    0.2.13) HEMATOLOGIC
    A) The n-propyl disulfide formed in various Allium species has hemolytic properties. Hemolytic anemia has been reported in animals. This effect has not been reported in humans who have ingested garlic.
    0.2.20) REPRODUCTIVE
    A) At the time of this review, no data were available to assess the potential effects of exposure to this agent during pregnancy or lactation.

Laboratory Monitoring

    A) No specific laboratory measures are indicated. Vomiting is seldom serious enough to cause electrolyte loss.

Treatment Overview

    0.4.2) ORAL/PARENTERAL EXPOSURE
    A) MANAGEMENT OF MILD TO MODERATE TOXICITY
    1) Treatment is symptomatic and supportive. Treatment is unlikely to be necessary in most cases. Consider dilution in patients that are not vomiting, develop a burning sensation of the gastrointestinal tract following ingestion. Patients, in particular children, may require IV hydration, antiemetics and electrolyte replacement if they develop significant vomiting and/or diarrhea. TOPICAL: Contact dermatitis has occurred with exposure. Avoid further contact and cleanse skin with soap and water. Monitor for ongoing skin reaction. Dermal injury can occur from prolonged direct contact with garlic. The area should be cleansed and treated similar to other chemical burns (ie, silver sulfadiazine cream).
    B) MANAGEMENT OF SEVERE TOXICITY
    1) Treatment is symptomatic and supportive. Severe toxicity is not anticipated with culinary use. Assess airway and respiratory function following a significant occupational exposure to garlic dust.
    C) DECONTAMINATION
    1) PREHOSPITAL: Gastric decontamination is rarely necessary. DILUTION: If no respiratory compromise is present, administer milk or water as soon as possible after ingestion. Dilution may only be helpful if performed in the first seconds to minutes after ingestion. The ideal amount is unknown; no more than 8 ounces (240 mL) in adults and 4 ounces (120 mL) in children is recommended to minimize the risk of vomiting.
    2) HOSPITAL: Gastric decontamination is rarely necessary. DILUTION: If no respiratory compromise is present, administer milk or water as soon as possible after ingestion. Dilution may only be helpful if performed in the first seconds to minutes after ingestion. The ideal amount is unknown; no more than 8 ounces (240 mL) in adults and 4 ounces (120 mL) in children is recommended to minimize the risk of vomiting.
    D) AIRWAY MANAGEMENT
    1) Airway support is unlikely to be necessary with culinary use. Monitor airway and respiratory function following an occupational exposure. Asthmatic reactions have been reported after multiple exposures to garlic dust.
    E) ENHANCED ELIMINATION
    1) No studies have addressed the utilization of extracorporeal elimination techniques in poisoning with this agent. However, enhanced elimination techniques are unlikely to be necessary following exposure to garlic.
    F) PATIENT DISPOSITION
    1) HOME CRITERIA: Most cases of exposure will require no therapy. Patients who are asymptomatic or with minimal symptoms after exposure to garlic may be managed at home.
    2) OBSERVATION CRITERIA: Patients who are symptomatic may need to be monitored until they are clearly improving and clinically stable.
    3) ADMISSION CRITERIA: Only patients with systemic toxicity (ie, respiratory insufficiency following occupational exposure) may require admission.
    4) CONSULT CRITERIA: Consult a regional poison center or medical toxicologist for assistance in managing patients with severe toxicity or in whom the diagnosis is not clear.
    0.4.4) EYE EXPOSURE
    A) DECONTAMINATION: Remove contact lenses and irrigate exposed eyes with copious amounts of room temperature 0.9% saline or water for at least 15 minutes. If irritation, pain, swelling, lacrimation, or photophobia persist after 15 minutes of irrigation, the patient should be seen in a healthcare facility.
    0.4.5) DERMAL EXPOSURE
    A) OVERVIEW
    1) DECONTAMINATION: Remove contaminated clothing and jewelry and place them in plastic bags. Wash exposed areas with soap and water for 10 to 15 minutes with gentle sponging to avoid skin breakdown. A physician may need to examine the area if irritation or pain persists (Burgess et al, 1999).

Range Of Toxicity

    A) TOXICITY: A single garlic clove may cause mucous membrane irritation. A significant ingestion can produce gastrointestinal symptoms including nausea, vomiting, abdominal cramping and diarrhea. A 25 mL dose of the extract caused dizziness and GI symptoms. Doses of 3 to 4 grams of garlic/day may alter fibrinolytic activity, and doses of 25 to 50 grams/day may alter platelet adhesiveness and blood fat composition.

Summary Of Exposure

    A) DESCRIPTION: A perennial plant with a bulbous base and erect, 2 to 3 foot tall stem. The bulb has a familiar "garlic" odor. Flowers are pink or purple and bloom from July to September in the Northern Hemisphere. USES: Garlic has been used in folk medicine since ancient Egypt and has had numerous herbal uses including alleged cure of leprosy, clotting disorders, deafness, earaches, scurvy, and flatulence, and as a disinfectant, antidote, anthelminthic, and cure for arteriosclerosis and gastroenteritis.
    B) COMPOSITION: Fresh garlic cloves have 0.1% to 0.3% of volatile oil, which is brown-yellow in color, and has a disagreeable odor. It consists primarily of allyl disulfide and allyl propyl disulfide with small amounts of higher polysulfides. EPIDEMIOLOGY: In general, garlic has not been shown to be toxic when used for culinary purposes.
    C) TOXICITY: The bulbs, bulblets, flowers and stems of the allium species (Allium canadense; wild garlic or wild onion) can produce toxicity if ingested in large quantities. However, plants grown commercially and consumed in smaller amounts do not usually produce adverse effects or illness.
    D) WITH POISONING/EXPOSURE
    1) ORAL: Ingestion of significant amounts may cause gastroenteritis (including nausea, vomiting, abdominal cramping and diarrhea) and hypoglycemia.
    2) OCULAR: Eye exposure may cause tearing.
    3) DERMAL: Skin contact may produce dermatitis and blistering following exposure. Dermal injury has also developed infrequently following prolonged contact with garlic cloves (eg, used as a poultice).
    4) GARLIC SUPPLEMENTS: Patients that ingest garlic tablets or herbal preparations containing garlic in large amounts may be at risk to develop bleeding secondary to potential inhibition of platelet aggregation.
    5) INHALATION: Inhalation of dust may produce asthmatic reactions following occupational exposure. CHRONIC: Iodine uptake may be reduced by chronic garlic ingestion

Heent

    3.4.1) SUMMARY
    A) Garlic vapors or eye contact with the clove oil may cause tearing.
    3.4.3) EYES
    A) Garlic vapors, or rubbing the material in the eyes may have a tearing effect (Block, 1985).

Cardiovascular

    3.5.2) CLINICAL EFFECTS
    A) BLOOD COAGULATION DISORDER
    1) Antithrombotic activity has been reported from various components of garlic. These may potentiate other anti-thrombotic or anti-atherosclerosis agents (Block et al, 1984).

Respiratory

    3.6.1) SUMMARY
    A) Allergic reactions have occurred after multiple exposures to garlic dust.
    3.6.2) CLINICAL EFFECTS
    A) BRONCHOSPASM
    1) WITH POISONING/EXPOSURE
    a) OCCUPATIONAL EXPOSURE
    1) Asthmatic reactions have been reported after multiple exposures to garlic dust (Anibarro et al, 1997; Lybarger et al, 1982; Henson, 1940; Couturier & Bousquet, 1982; Henson, 1940).
    2) Anibarro et al (1997) reported that 7 of 12 garlic workers developed occupational asthmatic reactions documented by specific inhalation challenges with garlic powder. Skin prick tests were also positive. Five of the 7 patients had levels of garlic-specific IgE greater than 0.7 kU/L (Anibarro et al, 1997).

Neurologic

    3.7.1) SUMMARY
    A) Dizziness, sweating, and lightheadedness were noted after a single 25 mL dose of garlic extract.
    3.7.2) CLINICAL EFFECTS
    A) DIZZINESS
    1) WITH POISONING/EXPOSURE
    a) Lightheadedness and sweating were noted after a single 25 mL dose of garlic extract (Caporaso et al, 1983).

Gastrointestinal

    3.8.1) SUMMARY
    A) A burning sensation of the mouth, stomach, and esophagus may develop after ingestion of garlic. Gastrointestinal upset is a common symptom of significant garlic ingestion.
    3.8.2) CLINICAL EFFECTS
    A) GASTROENTERITIS
    1) WITH POISONING/EXPOSURE
    a) Gastroenteritis and a burning sensation of the mouth, stomach, and esophagus were reported after a single 25 mL dose of garlic extract (Caporaso et al, 1983). Gastrointestinal upset is a common symptom of significant garlic ingestion (Lampe & McCann, 1985).
    B) NAUSEA AND VOMITING
    1) WITH POISONING/EXPOSURE
    a) A significant ingestion of garlic (allium species) can produce gastrointestinal symptoms including nausea and vomiting (Nelson et al, 2007).
    C) DIARRHEA
    1) WITH POISONING/EXPOSURE
    a) A significant ingestion of garlic (allium species) can produce gastrointestinal symptoms including abdominal cramping and diarrhea (Nelson et al, 2007).

Hepatic

    3.9.1) SUMMARY
    A) Chronic treatment with the garlic extract, in rats, for 2 months produced reductions in liver protein. The clinical significance of this is unknown.
    3.9.3) ANIMAL EFFECTS
    A) ANIMAL STUDIES
    1) HEPATOCELLULAR DAMAGE
    a) In a RAT study, chronic treatment with the extract for 2 months produced reductions in liver protein (Adamu et al, 1982). The clinical significance of this is unknown.

Hematologic

    3.13.1) SUMMARY
    A) The n-propyl disulfide formed in various Allium species has hemolytic properties. Hemolytic anemia has been reported in animals. This effect has not been reported in humans who have ingested garlic.
    3.13.2) CLINICAL EFFECTS
    A) HEMORRHAGE
    1) WITH POISONING/EXPOSURE
    a) SUMMARY: Patients that ingest garlic tablets or herbal preparations containing garlic in large amounts may be at risk to develop bleeding secondary to potential inhibition of platelet aggregation (Nelson et al, 2007).
    b) POSTOPERATIVE BLEEDING: Garlic ingestion has been associated with the occurrence of postoperative bleeding, which may be due to garlic's potential for inhibiting platelet aggregation (Burnham, 1995; German et al, 1995; Petry, 1995).
    c) CASE REPORT: It has been suggested that a spinal epidural hematoma with associated platelet dysfunction caused paraplegia in an 87-year-old man, all resulting from an excessive ingestion of garlic (4 cloves/day) (Rose et al, 1990).
    3.13.3) ANIMAL EFFECTS
    A) ANIMAL STUDIES
    1) ANEMIA HEMOLYTIC
    a) The n-propyl disulfide formed in various Allium species has hemolytic properties (Frohne & Pfander, 1984). Hemolytic anemia (with formation of Heinz bodies in the erythrocytes) has been reported in horses, cows, sheep, and dogs following ingestion of various Allium species (Rae, 1999; Stallbaumer, 1981; Hutchison, 1977; Pierce et al, 1972; Thorp & Harshfield, 1939). This effect has not been reported in humans.
    b) Heinz bodies and Howell-Jolly bodies were found in cows that ingested approximately 20 kilograms/day of onion for 6 weeks (Rae, 1999).
    c) Heinz body formation has been reported in several species of animals including cats, cattle, dogs, horses, and sheep (Robertson et al, 1998). In one prospective study in cats fed baby food with or without onion powder, heinz body formation rose to 33% to 53% (p < 0.0001).
    2) METHEMOGLOBINEMIA
    a) IN VITRO: Lehmann (1930) reported that as little as 1 ppm of garlic juice mixed with blood could cause methemoglobinemia. This effect has not been reported in humans ingesting garlic.
    b) Five of 50 cows that had ingested 20 kilograms/day of onion (Allium cepa) for 6 weeks developed methemoglobinemia and hemolytic anemia (Rae, 1999).
    c) In one prospective study in cats fed baby food with or without onion powder, methemoglobinemia levels rose to 1.2% in animals fed up to 2.5% onion powder for 2 months. The change in methemoglobinemia was significant (p < 0.0059), but not clinically important (Robertson et al, 1998).

Dermatologic

    3.14.2) CLINICAL EFFECTS
    A) ECZEMA
    1) WITH POISONING/EXPOSURE
    a) Occupational eczema has been reported in cooks exposed to garlic (Eming et al, 1999) (Papagerogiou et al, 1983) (van Ketel & de Haan, 1978; Sinha et al, 1977; Bleumink & Nater, 1973; Edelstein, 1950). Diallyldisulfide is suspected of being the primary irritant in garlic (Bojs & Svensson, 1988).
    b) Patch testing of 63 patients with leg ulcers and 168 patients with dermatitis produced 14 with positive reactions to garlic. Only 2 of these considered they might have a garlic sensitivity (Bleumink & Nater, 1973).
    c) CASE REPORT: A 78-year-old man with history of hand eczema presented with generalized eczema after exposure to wet dressings containing crushed garlic cloves. Excoriations and small erosions on the legs were being treated with hydrocortisone and garlic dressings. The dermatitis gradually spread to the trunk and arms. The patient had an increased total IgE of 350 kU/liter. Nine days of treatment with oral and topical steroids cleared the eczema. Patch testing with garlic preparations was positive. Patch testing with a 10% solution produced ulceration and erythema. Patch testing with diallyldisulfide also produced a strong reaction (Bojs & Svensson, 1988).
    B) CONTACT DERMATITIS
    1) WITH THERAPEUTIC USE
    a) Contact dermatitis has been reported after exposure to garlic and onion (Papagerogiou et al, 1983) (Mitchell, 1980; Sinha et al, 1977; Bleumink & Nater, 1973). This has occurred after handling during cooking, and after use as a topical medicine (Delaney & Donnelly, 1996; McFadden et al, 1992; Lee & Lam, 1991; Lembo et al, 1991; Bojs & Svensson, 1988). There appears to be some cross-reactivity between garlic and onion (Bleumink & Nater, 1973). Both immediate and delayed sensitization to garlic have been reported (Campolmi et al, 1982).
    b) CASE REPORT: A 58-year-old ma began taking garlic extract tablets to treat hyperlipidemia and subsequently developed contact hand dermatitis which persisted for 8 months. The dermatitis resolved after the patient ran out of garlic tablets. Patch testing with extracts of garlic were positive. Upon rechallenge with ingestion of garlic tablets for one week, the patient's hand dermatitis returned (Burden et al, 1994).
    c) CASE REPORT: A 37-year-old woman developed eruptions on the fingers after handling garlic and onions. Patch testing with raw cut surfaces of onions and garlic were positive, with garlic producing a more serious and longer lasting reaction (Burks, 1954).
    C) BULLOUS ERUPTION
    1) WITH POISONING/EXPOSURE
    a) Bullous lesions with vesicles, dark erosions, and erythema resulted from the purposeful application of crushed garlic to the skin by soldiers hoping to improve their military assignments (Kaplan et al, 1990).
    b) CASE REPORT: A child developed blisters and ulceration after having garlic cloves taped to his wrist for six hours. Lesions healed in 3 weeks, leaving cicatries (Garty, 1993).
    D) CHEMICAL BURN
    1) WITH POISONING/EXPOSURE
    a) CASE REPORT: A 38-year-old woman who was breastfeeding applied a garlic poultice to her left breast, in order to treat a rash that she presumed to be thrush, and left the poultice in place for two days despite a burning sensation. The patient presented to the ED 2 days after removing the poultice due to discomfort. Physical examination of the left breast revealed areas of skin loss, ulcerations, crusting, hyperpigmentation, and granulation tissue formation. The skin was cleansed and the patient was given 1% silver sulfadiazine cream for treatment of the burn (Roberge et al, 1997).
    b) CASE REPORT: A burn of the left hand was reported on a 42-year-old woman who held crushed garlic the day before. She held the garlic for 3 to 5 minutes. Ten hours later, a burning sensation and edema were noted, developing into a sharply demarcated erythematous eruption that was partly bullous and partly hemorrhagic (Eming et al, 1999).

Endocrine

    3.16.2) CLINICAL EFFECTS
    A) FINDING OF THYROID FUNCTION
    1) WITH THERAPEUTIC USE
    a) Iodine uptake may be reduced by chronic garlic ingestion (Willis, 1966).

Reproductive

    3.20.1) SUMMARY
    A) At the time of this review, no data were available to assess the potential effects of exposure to this agent during pregnancy or lactation.
    3.20.2) TERATOGENICITY
    A) LACK OF INFORMATION
    1) At the time of this review, no data were available to assess the teratogenic potential of this agent.
    3.20.3) EFFECTS IN PREGNANCY
    A) LACK OF INFORMATION
    1) HUMANS - At the time of this review, no data were available to assess the potential effects of exposure to onions or garlic during pregnancy or lactation in humans.
    B) ANIMAL STUDIES
    1) ABORTION
    a) Two near-term pregnant cows aborted after eating approximately 20 kilograms/day of onion (Allium cepa) for 6 weeks (Rae, 1999).

Carcinogenicity

    3.21.3) HUMAN STUDIES
    A) LACK OF INFORMATION
    1) At the time of this review, no data were available to assess the carcinogenic or mutagenic potential of this agent.
    B) UNEXPECTED THERAPEUTIC BENEFIT
    1) There is some evidence in animals and humans that diets with Allium species have an anti-tumor effect, especially on cancers such as stomach cancer (You et al, 1989).

Monitoring Parameters Levels

    4.1.1) SUMMARY
    A) No specific laboratory measures are indicated. Vomiting is seldom serious enough to cause electrolyte loss.

Monitoring

    A) No specific laboratory measures are indicated. Vomiting is seldom serious enough to cause electrolyte loss.

Oral Exposure

    6.5.1) PREVENTION OF ABSORPTION/PREHOSPITAL
    A) SUMMARY
    1) Gastric decontamination is rarely necessary.
    B) DILUTION
    1) DILUTION: If no respiratory compromise is present, administer milk or water as soon as possible after ingestion. Dilution may only be helpful if performed in the first seconds to minutes after ingestion. The ideal amount is unknown; no more than 8 ounces (240 mL) in adults and 4 ounces (120 mL) in children is recommended to minimize the risk of vomiting (Caravati, 2004).
    6.5.2) PREVENTION OF ABSORPTION
    A) SUMMARY
    1) Gastric decontamination is rarely necessary.
    B) DILUTION
    1) DILUTION: If no respiratory compromise is present, administer milk or water as soon as possible after ingestion. Dilution may only be helpful if performed in the first seconds to minutes after ingestion. The ideal amount is unknown; no more than 8 ounces (240 mL) in adults and 4 ounces (120 mL) in children is recommended to minimize the risk of vomiting (Caravati, 2004).
    6.5.3) TREATMENT
    A) SUPPORT
    1) MANAGEMENT OF MILD TO MODERATE TOXICITY
    a) Treatment is symptomatic and supportive. Treatment is unlikely to be necessary in most cases. Consider dilution in patients that are not vomiting, develop a burning sensation of the gastrointestinal tract following ingestion. Patients, in particular children, may require IV hydration, antiemetics and electrolyte replacement if they develop significant vomiting and/or diarrhea. TOPICAL: Contact dermatitis has occurred with exposure. Avoid further contact and cleanse skin with soap and water. Monitor for ongoing skin reaction. Dermal injury can occur from prolonged direct contact with garlic. The area should be cleansed and treated similar to other chemical burns (ie, silver sulfadiazine cream).
    2) MANAGEMENT OF SEVERE TOXICITY
    a) Treatment is symptomatic and supportive. Severe toxicity is not anticipated with culinary use. Assess airway and respiratory function following a significant occupational exposure to garlic dust.
    B) MONITORING OF PATIENT
    1) No specific laboratory measures are indicated. Vomiting is seldom serious enough to cause electrolyte loss.

Eye Exposure

    6.8.1) DECONTAMINATION
    A) EYE IRRIGATION, ROUTINE: Remove contact lenses and irrigate exposed eyes with copious amounts of room temperature 0.9% saline or water for at least 15 minutes. If irritation, pain, swelling, lacrimation, or photophobia persist after 15 minutes of irrigation, an ophthalmologic examination should be performed (Peate, 2007; Naradzay & Barish, 2006).

Dermal Exposure

    6.9.1) DECONTAMINATION
    A) DECONTAMINATION: Remove contaminated clothing and wash exposed area thoroughly with soap and water for 10 to 15 minutes. A physician may need to examine the area if irritation or pain persists (Burgess et al, 1999).
    6.9.2) TREATMENT
    A) BURN
    1) Both oral and topical steroids have been used to treat various garlic-induced burns and rashes (Bojs & Svensson, 1988).
    2) Ten hours after holding crushed garlic for 3 to 5 minutes, a burning sensation and edema were noted, developing into a sharply demarcated erythematous eruption that was partly bullous and partly hemorrhagic. The lesion cleared after 10 days of treatment with triamcinolone acetonide 0.1% (Eming et al, 1999).
    B) Treatment should include recommendations listed in the ORAL EXPOSURE section when appropriate.

Enhanced Elimination

    A) LACK OF INFORMATION
    1) No studies have addressed the utilization of extracorporeal elimination techniques in poisoning with this agent. However, enhanced elimination techniques are unlikely to be necessary following exposure to garlic.

Life Support

    A) Support respiratory and cardiovascular function.

Patient Disposition

    6.3.1) DISPOSITION/ORAL EXPOSURE
    6.3.1.1) ADMISSION CRITERIA/ORAL
    A) Only patients with systemic toxicity (ie, respiratory insufficiency) may require admission.
    6.3.1.2) HOME CRITERIA/ORAL
    A) Most cases of exposure will require no therapy. Patients who are asymptomatic or with minimal symptoms after exposure to garlic may be managed at home.
    6.3.1.3) CONSULT CRITERIA/ORAL
    A) Consult a regional poison center or medical toxicologist for assistance in managing patients with severe toxicity or in whom the diagnosis is not clear.
    6.3.1.5) OBSERVATION CRITERIA/ORAL
    A) Patients who are symptomatic may need to be monitored until they are clearly improving and clinically stable.

Summary

    A) TOXICITY: A single garlic clove may cause mucous membrane irritation. A significant ingestion can produce gastrointestinal symptoms including nausea, vomiting, abdominal cramping and diarrhea. A 25 mL dose of the extract caused dizziness and GI symptoms. Doses of 3 to 4 grams of garlic/day may alter fibrinolytic activity, and doses of 25 to 50 grams/day may alter platelet adhesiveness and blood fat composition.

Therapeutic Dose

    7.2.1) ADULT
    A) GENERAL
    1) The expressed garlic juice has been used in doses of 2 milliliters, and there was a standard syrup preparation (Syrupus Allii N.F. V) used in doses of 4 to 8 milliliters. The dose of the oil used is 0.12 to 0.2 milliliter (Okuyama et al, 1989).

Maximum Tolerated Exposure

    A) SUMMARY
    1) The bulbs, bulblets, flowers and stems of the allium species (Allium canadense; wild garlic or wild onion) can produce toxicity if ingested in large quantities. However, plants grown commercially and consumed in smaller amounts do not usually produce adverse effects or illness (Nelson et al, 2007).
    2) A significant ingestion can produce gastrointestinal symptoms including nausea, vomiting, abdominal cramping and diarrhea (Nelson et al, 2007).
    3) Patients that ingest garlic tablets or herbal preparations containing garlic in large amounts may be at risk to develop bleeding secondary to potential inhibition of platelet aggregation (Nelson et al, 2007).
    4) A single garlic clove may cause mucous membrane irritation. A 25 mL dose of the extract caused dizziness and GI symptoms (Caporaso et al, 1983).
    5) Doses of 3 to 4 g of garlic/day may alter fibrinolytic activity, and doses of 25 to 50 grams/day may alter platelet adhesiveness and blood fat composition (Roser, 1990). Doses are estimates only and are not specific to the form consumed (dried, raw, cooked, fried, oils, etc).
    B) CASE REPORTS
    1) It has been suggested that an 87-year-old man developed a spinal epidural hematoma with associated platelet dysfunction causing paraplegia from the excessive ingestion of 4 cloves of garlic/day (Rose et al, 1990).

Pharmacologic Mechanism

    A) When a garlic bulb is crushed, allinase is released and converts alliin to 2-propenesulfenic acid, which dimerizes creating allicin. This compound is responsible for the characteristic odor of garlic and some of its pharmacologic activity. Allicin itself has no biologic action (Block, 1985).
    B) THERAPEUTIC EFFECTS -
    1) SUGGESTED THERAPEUTIC EFFECTS -
    a) ALLIUM SATIVUM (GARLIC) - Anticoagulant, antihypertensive, antimicrobial, immune system modulator, antilipidemic agent, hypoglycemic agent, and fibrinolytic activity (Abdullah et al, 1988; Anon, 1976).
    b) ALLIUM CEPA (ONION) - Hypocholesterolemic, fibrinolytic agents (most likely propienyl and methyl sulfides), inhibition of thrombocyte aggregation, fatty acid oxygenases, antiasthmatics (Bayer et al, 1989; Anon, 1976).
    c) ALLIUM URSINUM (WILD GARLIC) - Inhibits 5-lipooxygenase, cyclooxygenase, thrombocyte aggregation, and angiotensin I converting enzyme (Sendl et al, 1992).
    2) CHOLESTEROL AND TRIGLYCERIDES -
    a) RATS - Administration of 100 mg/kg/day of garlic oil to rats blocked increases in cholesterol, triglycerides and total lipids when compared to controls who were also fed a high sucrose diet (Adamu et al, 1982). Another rat study confirmed these results (Kamanna & Chandrasekhara, 1984). The anti-atherogenic action is present in the oily fraction of garlic (Jain & Konar, 1978).
    b) When tested in humans given 100 g of butter in a fatty diet, a 7% increase from prestudy cholesterol levels was reported in the non-treated groups, and a 7% decrease was reported in the group also given 50 grams of garlic. Serum cholesterol levels were measured 3 hours post ingestion. There were only 10 subjects in the study (Bordia & Bansal, 1973).
    c) Another study involved 20 healthy volunteers. Serum cholesterol and triglycerides were decreased, while high density lipoproteins were increased after a dose of 0.25 mg/kg/day of garlic oil (Bordia, 1981).
    d) Similar results were seen in 62 patients with coronary artery disease and elevated cholesterol who used garlic for 10 months (Bordia, 1981); and in a study done by Sharma et al (1978).
    e) There have been eleven studies with doses of 600 to 900 mg of garlic powder per day that have shown an average reduction of serum cholesterol and triglycerides of 10% to 13% (Grunwald, 1990; Mader, 1990).
    f) Onion reduced hypercholesterolemia from 7% to 33% in 9 of 18 patients with blood cholesterol of 245 to greater than 300 milligrams/deciliter. Patients ingested 15 mL of onion extract 2 or 3 times daily for at least 3 months. Of these patients, 33% had approximately a 5% decrease, 11.1% had a 5% to 9% decrease, 5.6% had a 10% to 14% decrease, and 16.7% had either a 15% to 19% decrease, a 20% to 40% decrease, or an increase in serum cholesterol levels (Louria et al, 1985).
    3) FIBRINOLYTIC ACTIVITY -
    a) Human volunteers fed 50 g of garlic with 100 g of butter had a 15% increase in fibrinolytic activity 3 hours post-ingestion, compared to a group fed the butter alone (Bordia & Bansal, 1973).
    b) Bordia et al (1977) found a 95% increase in fibrinolytic activity in post MI patients over the initial post infarct period.
    c) Amounts close to 3 to 4 grams/day may produce an effect on fibrinolytic activity (Roser, 1990).
    4) PLATELET FUNCTION INHIBITION -
    a) GARLIC -
    1) Makheja et al (1979) found that garlic oil inhibited platelet function, most likely by thromboxane synthesis. Amounts close to 25 to 50 grams/day may alter platelet adhesiveness (Roser, 1990).
    2) One very potent antithrombotic compound found in garlic is 4,5,9 trithiadodeca-1,6;11-triene 9 oxide (ajoene). Ajoene appears to inhibit platelet aggregation no matter what method of induction is used (Anon, 1994).
    3) Ariga et al (1981) found that methylallyltrisulfide (found at 4 to 10% in the oil) inhibited ADP-induced platelet aggregation at under 10 micromoles/liter in plasma.
    4) Fresh garlic also appears to inhibit platelet aggregation. One study found complete inhibition of platelet aggregation to 5-hydroxytryptamine for 1 hour after ingestion of 100 to 150 mg/kg of fresh garlic (Boullin, 1981). Not all studies are positive. Dried garlic, given in sugar coated tablets, had no effect on blood lipids or blood coagulation when administered in a double-blind study to 85 patients in doses of either 198 mg three times daily or 450 mg three times daily (Luley et al, 1986).
    5) Apitz-Castro et al (1983) found that an alcoholic extract of garlic and 3 other specific factors from garlic inhibited platelet aggregation induced by a number of agents.
    b) ONION -
    1) No statistical difference was measured in platelet thromboxane production in one small study (n=5) of human volunteers ingesting 70 grams of raw onion (species not cited) daily for 7 days (Srivastava, 1989).
    2) The n-butanol soluble fraction from Allium bakeri inhibits human platelet aggregation in vitro. The primary effective agent appeared to be adenosine (Okuyama et al, 1988).
    3) Nine patients were fed either a high-fat or a low-fat meal. The high-fat meal induced an increase in platelet aggregation (p < 0.02) when compared with the low-fat meal. If 75 grams of onions (Allium cepa) were added to the high-fat meal, no significant increase in platelet aggregation was found. There was no significant change in fibrinolysis after the addition of the onion (Baghurst et al, 1977).
    5) HYPOGLYCEMIC EFFECTS -
    a) Rabbits given garlic had a 12% reduction in blood sugar (compared to 20% for tolbutamide) (Jain et al, 1973). Increases in serum insulin and improvement in liver glycogen storage has also been noted in humans taking garlic (Sitprija et al, 1987).
    b) Onion has been shown to contain diphenylamine. When given to rabbits, pure diphenylamine caused a 21.7% to 33.4% reduction in blood sugar. A diethyl ether extract from onion produced a 34.8% to 50.3% reduction in blood glucose (Salveron & Cantoria, 1989).
    6) ANTIBIOTIC -
    a) ANTIBACTERIAL - Garlic does inhibit both gram-positive and gram-negative organisms. It is about 1% as effective as penicillin (Anon, 1994; Willis, 1956).
    b) ANTIFUNGAL - Although tested as an antifungal with positive results, garlic has not proven to be very useful or popular as a general antifungal (Anon, 1994; Adetumbi & Lau, 1983; Amer et al, 1980; Moore & Atkins, 1977).
    c) ANTIVIRAL - Garlic extract was shown to have antiviral activity against influenza B, human rhinovirus, vaccinia virus, vesicular stomatitis virus, parainfluenza type 3, and herpes simplex, but not against Coxsackie B1 virus (Weber et al, 1991; (Tsai et al, 1985). Various components of the garlic were tested. The order of virucidal activity, in decreasing order, was ajoene, allicin, allyl methylthiosulfinate, and methyl allylthiosulfinate (Weber et al, 1991).
    d) AMEBICIDAL - Addition of 25 mcg/mL of crude garlic extract oil to cultures of Entamoeba histolytica trophozoites inhibited growth. Concentrations of about 50 mcg/mL produced irreversible killing (Mirelman et al, 1987).
    7) ANTINEOPLASTIC -
    a) When mice with malignancies were pretreated with garlic extract, no treated mice died in 6 months, whereas all control mice expired (Weisberger & Pensky, 1957). It is postulated that allicin may react with the sulfhydryl groups found in rapidly dividing cells, reducing their growth rate.
    b) The germanium and selenium found in garlic may have some effect on reducing tumor growth rate. Garlic extracts have been shown to inhibit liver and buccal tumors in experimental animals (Anon, 1994; Hayes et al, 1987).
    c) Garlic and onion were also shown to inhibit tumors promoted by phorbol-myristate acetate (Belman, 1983).
    d) An epidemiologic study found that patients who ingested larger amounts of Allium vegetables had fewer stomach cancers than those who ate fewer. Not all other factors were controlled. Interviews were conducted, in China, with 564 patients with stomach cancer and 1,131 controls. Persons in the highest quartile of intake had only 40% of the risk of those in the lowest quartile (You et al, 1989).
    8) ANTIHEPATOTOXIC EFFECT -
    a) When tested in in-vitro and in-vivo animal models, garlic was shown to have a protective effect against hepatotoxicity induced by carbon tetrachloride and galactosamine (Hikino et al, 1986).
    9) ANTIASTHMATIC EFFECT -
    a) Alpha- and beta-unsaturated thiosulfinates found in Allium cepa exhibit antiasthmatic effects in vivo. Allergen-induced bronchial obstruction in guinea pigs was suppressed and in vitro inhibition of histamine release, leukotriene synthesis, and thromboxane production were noted in human cell cultures (Bayer et al, 1989; Dorsch et al, 1988).
    10) ANTIHYPERTENSIVE EFFECT -
    a) Administration of 15 mL of onion extract 2 to 3 times daily for 2 months decreased blood pressure in 13 of 20 patients with moderate hypertension (systolic pressure less than 185 mmHg and diastolic pressure less than 110 mmHg). The mean decrease was 6.6 mmHg (p = 0.000132) (Louria et al, 1985).

Toxicologic Mechanism

    A) REDUCED ENZYME ACTIVITY -
    1) The organic disulfides in garlic oil may reduce the thiol activity of certain enzymes and may also effect NADPH. Thus, enzymes such as coenzyme A, coenzyme A reductase, and NADPH may have their activity reduced (Anon, 1994; Willis, 1956).
    2) Garlic is known to inhibit 5-lipooxygenase, cyclooxygenase, and angiotensin I converting enzyme (Sendl et al, 1992).
    3) Allium sativum sap and rehydrated powder were found to inhibit the enzyme adenosine deaminase in a dose-dependent manner in vitro. This leads to an accumulation of adenosine which may alter heart rate and blood pressure (Koch et al, 1992).
    B) PLATELET FUNCTION INHIBITION -
    1) Garlic oil contains methylallyltrisulfide (MATS) (4 to 10% of the content of the natural oil), which inhibits platelet function, most likely due to thromboxane synthesis (Makheja et al, 1979). MATS in pure form inhibits ADP-induced platelet aggregation in concentrations of under 10 micromoles/liter in plasma (Ariga et al, 1981).
    2) Ajoene, a rearrangement product of allicin is a potent inhibitor of platelet aggregation in vitro via inhibition of granule release and fibrinogen binding (McElnay & Li Wan Po, 1991; Rendu et al, 1989).
    3) IN VITRO - It was shown that garlic oil, in a dose-dependent manner, decreased the adherence of fibrinogen on a polymer surface. It is thought that platelets adhere to places were fibrinogen had adhered (Sharma & Sunny, 1988). Phillips & Poyser (1978) have also shown in vitro inhibition of platelet aggregation using various onion extracts.
    C) ANTIHEPATOTOXIC EFFECT -
    1) Garlic oil alliin, S-allylmercaptocysteine and S-methylmercapto-cysteine were found to have marked antihepatotoxic effects in a primary cultured rat hepatocyte system tested against carbon tetrachloride and galactosamine-induced toxicity. The volatile oil inhibited carbon tetrachloride-induced free radical formation and lipid peroxidation (Hikino et al, 1986).
    D) HEMOLYTIC EFFECT -
    1) N-propyl disulfides in Allium species are hemolytic (Rae, 1999).
    2) Allium species also contain the somewhat rare amino acids S-meth- and S- prop(en)ylcysteine sulfoxides (SMCO). In ruminants, SMCO is converted to thiosulfonates then to hemolytic dipropyl disulfides and dipropenyl disulfides (Rae, 1999). Rumen bacteria appear to be involved in producing oxidative stress and hemolytic anemia in sheep (Mohamed et al, 1999).
    3) These disulfides produce methemoglobinemia and hemolytic anemia by first being reduced by glutathione and glutathione peroxidase to thiols, then oxidation of these thiols by oxyhemoglobin (producing free radicals). Also, during this process, hemoglobin is converted to methemoglobin. Other reactive oxygen species formed include superoxide anion and hydrogen peroxide (Rae, 1999). In dogs, reduced erythrocyte glutathione accelerated oxidative damage caused by n-propylthiosulfate (Yamato et al, 1999).
    4) There is wide species variation in susceptibility to oxidative damage. Species in order of decreasing susceptibility are cats, dogs, cattle, horses, sheep, goats, rats, mice, humans (Rae, 1999).
    E) ANTIBIOTIC -
    1) Allicin methyl allyl thiosulfinate, and allyl methyl thiosulfinate are antibiotics (Hughes & Lawson, 1991). Some initial studies would indicate that the target enzyme for this activity may be the enzyme acetyl-CoA synthetase (Focke et al, 1990).
    2) Onion and garlic (reconstituted dehydrated powders) were found to be bactericidal (in vitro) in concentrations of 1% and 5%, respectively, with maximal death rates at 5% and 10%, respectively. Salmonella typhimurium was equally susceptible to both agents; Escherichia coli was less sensitive to onion (Johnson & Vaughn, 1969).

Clinical Effects

    11.1.2) BOVINE/CATTLE
    A) METHEMOGLOBINEMIA - Five of 50 cows that had ingested 20 kilograms/day of onion (Allium cepa) for 6 weeks developed methemoglobinemia and hemolytic anemia (Rae, 1999).
    B) HEINZ BODY FORMATION/ANEMIA
    1) Heinz body formation has been reported in several species of animals including cats, cattle, dogs, horses, and sheep (Robertson et al, 1998).
    2) Heinz bodies and Howell-Jolly bodies were found in cows that ingested approximately 20 kilograms/day of onion for 6 weeks (Rae, 1999).
    C) ABORTION - Two near-term pregnant cows aborted after eating approximately 20 kilograms/day of onion (Allium cepa) for 6 weeks (Rae, 1999).
    11.1.3) CANINE/DOG
    A) HEINZ BODY FORMATION/ANEMIA
    1) Heinz body formation has been reported in several species of animals including cats, cattle, dogs, horses, and sheep (Robertson et al, 1998).
    2) The susceptibility of dogs, for the development of hemolytic anemia, is dependent on the type of erythrocytes they have. High potassium, high glutathione erythrocyte dogs are more susceptible to the oxidant action of onions than normal to low potassium erythrocyte dogs (Yamato et al, 1999; Yamoto & Maede, 1992).
    11.1.5) EQUINE/HORSE
    A) HEINZ BODY FORMATION/ANEMIA - Heinz body formation has been reported in several species of animals including cats, cattle, dogs, horses, and sheep (Robertson et al, 1998).
    11.1.6) FELINE/CAT
    A) HEINZ BODY/ANEMIA
    1) Heinz body formation has been reported in several species of animals including cats, cattle, dogs, horses, and sheep (Robertson et al, 1998).
    2) In one prospective study in cats fed baby food with or without onion powder, heinz body formation rose 33% to 53% (p < 0.0001) and methemoglobinemia levels rose to 1.2% in animals fed up to 2.5% onion powder for 2 months. The change in methemoglobinemia was significant (p < 0.0059), but not clinically important (Robertson et al, 1998).
    11.1.8) LAGOMORPH/RABBIT
    A) HYPOGLYCEMIC EFFECTS - Rabbits given garlic had a 12% reduction in blood sugar (compared to 20% for tolbutamide) (Jain et al, 1973).
    11.1.9) OVINE/SHEEP
    A) HEINZ BODY FORMATION/ANEMIA - Heinz body formation has been reported in several species of animals including cats, cattle, dogs, horses, and sheep (Robertson et al, 1998).

Range Of Toxicity

    11.3.2) MINIMAL TOXIC DOSE
    A) CATS - In one prospective study in cats fed baby food with or without onion powder, heinz body formation rose 33% to 53% (p < 0.0001) and methemoglobinemia levels rose to 1.2% in animals fed up to 2.5% onion powder for 2 months. The change in methemoglobinemia was significant (p < 0.0059), but not clinically important (Robertson et al, 1998).
    B) COWS - Five of 50 cows that had ingested 20 kilograms/day of onion (Allium cepa) for 6 weeks developed methemoglobinemia and hemolytic anemia (Rae, 1999).
    C) SHEEP - Sheep fed onions for 5 to 6 days may exhibit signs and symptoms of methemoglobinemia and anemia. Sheep fed 50 grams/day of onion for 15 days developed significant anemia (Selim et al, 1999).

Pharmacology Toxicology

    A) HEMOLYTIC EFFECT
    1) N-propyl disulfides in Allium species are hemolytic (Rae, 1999).
    2) Allium species also contain the somewhat rare amino acids S-meth- and S- prop(en)ylcysteine sulfoxides (SMCO). In ruminants, SMCO is converted to thiosulfonates then to hemolytic dipropyl disulfides and dipropenyl disulfides (Rae, 1999). Rumen bacteria appear to be involved in producing oxidative stress and hemolytic anemia in sheep (Mohamed et al, 1999).
    3) These disulfides produce methemoglobinemia and hemolytic anemia by first being reduced by glutathione and glutathione peroxidase to thiols, then oxidation of these thiols by oxyhemoglobin (producing free radicals). Also, during this process, hemoglobin is converted to methemoglobin. Other reactive oxygen species formed include superoxide anion and hydrogen peroxide (Rae, 1999). In dogs, reduced erythrocyte glutathione accelerated oxidative damage caused by n-propylthiosulfate (Yamato et al, 1999).
    4) There is wide species variation in susceptibility to oxidative damage. Species in order of decreasing susceptibility are cats, dogs, cattle, horses, sheep, goats, rats, mice, humans (Rae, 1999).

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