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PEPPERMINT OIL

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Classification   |    Detailed evidence-based information

Substances Included Synonyms

Therapeutic Toxic Class

    A) Peppermint oil is a volatile oil derived from several natural sources including Mentha piperita (L.). Mentha piperita is a cross (hybrid) of M. spicata and M. aquatica.

Specific Substances

    1) Menthae Piperitae Aetheroleum
    2) Oleum Menthae Piperitae
    3) Ol. Menth. Pip.
    4) Essence de Menthe Poivree
    5) Pfefferminzoel
    6) Mentha Oil
    7) Oleum Menthae Brasiliensis
    8) Essencia de Hortela-Pimenta
    9) CAS 8006-90-4
    10) NIOSH/RTECS SC 6125000
    11) OIL OF PEPPERMINT

Available Forms Sources

    A) FORMS
    1) Generally, peppermint oil contains 29% to 48% menthol, 20% to 31% menthone, and a varying amount (5% to 9%) of menthyl acetate (HSDB , 2001).
    B) SOURCES
    1) OIL: Peppermint oil is a volatile oil obtained from steam distillation of the flowering plant (Mentha piperita (L). This is a cross (hybrid) of M. spicata and M. aquatica) which yields approximately 0.3% to 0.7% (HSDB , 2001). Peppermint spirits contain 10% peppermint oil in alcohol. (Anon, 1990). The official product contains 50% or more menthol or its esters (Gosselin et al, 1984).
    2) SUSTAINED RELEASED/DELIVERY SYSTEM: A triple coated microsphere formulation with sustained release of peppermint oil in the small intestine has been developed. This process converts peppermint oil into a solid-state matrix with microcrystalline cellulose as a spherical core that is designed for release over 4 hours. It has been designed for sustained release in the small intestine and is used to provide rapid relief of irritable bowel syndrome symptoms. Each capsule contains 180 mg of peppermint oil (Cash et al, 2016).
    3) CONSTITUENTS: More than 100 components have been isolated from peppermint oil. The concentrations vary with cultivar and growth conditions and locale (Hoffman & Lunder, 1984; Maffei & Sacco, 1987).
    C) USES
    1) Peppermint oil is used primarily as a flavoring and aromatic in a wide variety of products. As an alternative medicine, it has been used as an antispasmodic, an antiseptic, and as an anti-HSV1 and anti-HSV2 antiviral. Additionally, peppermint oil has been used to treat cramps, dyspepsia, nausea, the common cold, sore throat, and to relieve symptoms of irritable bowel syndrome and tension headaches. It may also be used topically to treat myalgia and neuralgia (Cash et al, 2016; HSDB , 2001; Blumenthal et al, 1998; Anon, 1990).
    2) The delivery system for PO used in this study consists of a triple-coated microsphere formulation with sustained release of PO in the small intestine. The SST technology is implemented by converting the PO into a solid-state matrix with microcrystalline cellulose as a spherical core. The core is designed for release over 4 h. There is a seal coat surrounding the core to trap the terpenes. The middle coat is an enteric polymer, which dissolves at the intestinal pH and is insoluble at the gastric pH. The external coat contains a non-mucoadhesive polymer that facilitates faster transit through the stomach. The microspheres have an average diameter of less than 1.5 mm to allow flow through the pylorus

Overview

Life Support

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

Clinical Effects

    0.2.1) SUMMARY OF EXPOSURE
    A) USES: Peppermint oil is used primarily as a flavoring and aromatic in a wide variety of products. As an alternative medicine, it has been used as an antispasmodic, an antiseptic, and as an anti-HSV1 and anti-HSV2 antiviral. Additionally, peppermint oil has been used to treat cramps, dyspepsia, nausea, the common cold, sore throat, and to relieve symptoms of irritable bowel syndrome and tension headaches. It may also be used topically to treat myalgia and neuralgia.
    B) PHARMACOLOGY: Menthol, the major constituent of peppermint oil, blocks calcium channels causing smooth muscle relaxation.
    C) TOXICOLOGY: Toxicity following overdose is due to the actions of menthol.
    D) EPIDEMIOLOGY: Overdose is rare.
    E) WITH POISONING/EXPOSURE
    1) Reported cases of menthol toxicity are rare. The most commonly reported symptoms are ataxia, confusion, coma, nausea, and vomiting. Animals have developed CNS depression, ataxia, seizures, and coma.
    0.2.20) REPRODUCTIVE
    A) Peppermint oil has been used to induce menstruation and should, therefore, be avoided in pregnancy.

Laboratory Monitoring

    A) Routine laboratory monitoring is not necessary unless otherwise clinically indicated.
    B) Monitor vital signs and mental status.
    C) Obtain a chest x-ray if aspiration is suspected.

Treatment Overview

    0.4.2) ORAL/PARENTERAL EXPOSURE
    A) MANAGEMENT OF TOXICITY
    1) Treatment is symptomatic and supportive. Monitor for CNS depression and ensure the patient is able to protect their airway. Nausea, vomiting and dehydration should be treated with IV fluids and antiemetics.
    B) DECONTAMINATION
    1) PREHOSPITAL: Gastrointestinal decontamination is not generally indicated.
    2) HOSPITAL: Gastrointestinal decontamination is not generally indicated. However, activated charcoal may be considered for recent, large, deliberate ingestions if the patient is alert or airway is protected.
    C) AIRWAY MANAGEMENT
    1) Ensure adequate ventilation and perform endotracheal intubation early in patients with significant CNS or respiratory depression.
    D) ANTIDOTE
    1) There is no specific antidote.
    E) PATIENT DISPOSITION
    1) HOME CRITERIA: Patients with inadvertent exposures who have only minor GI irritation may be observed at home.
    2) OBSERVATION CRITERIA: Patients with any CNS depression, severe GI irritation, or deliberate ingestion should be referred to a healthcare facility.
    3) ADMISSION CRITERIA: Patients with persistent CNS depression or respiratory distress should be admitted.
    4) CONSULT CRITERIA: Consult a medical toxicologist or poison center for patients with severe toxicity.
    F) PITFALLS
    1) Missing an ingestion of another chemical or other possible etiologies for a patient’s symptoms.
    G) PHARMACOKINETICS
    1) Menthol is hydroxylated and subsequently metabolized by the CYP450 system. The metabolites are glucuronidated and renally excreted.
    H) DIFFERENTIAL DIAGNOSIS
    1) Other chemicals or drugs that cause CNS depression (eg, toxic alcohols, benzodiazepines, opiates/opioids, antipsychotic medications). Diseases or exposures that produce acute respiratory distress (eg, inhalation of acid or alkaline mists, asthma, COPD).

Range Of Toxicity

    A) TOXICITY: A specific toxic dose has not been established. Apnea, cyanosis, and respiratory arrest occurred in an infant after direct application of menthol to the nares. A 13-year-old boy experienced CNS depression, vertigo, and ataxia after inhaling 200 mg of menthol.
    B) THERAPEUTIC DOSE: There is no well-established therapeutic dose. ADULT: ORAL CAPSULE: 0.2 to 0.4 mL 3 times daily in enteric coated capsules. INHALATION: 3 to 4 drops in hot water. OIL (INTERNAL): 6 to 12 drops daily. THROAT LOZENGE: Throat lozenges contain 5 to 10 mg of menthol and have not been associated with significant toxicity. PEDIATRIC: CHILDREN 8 YEARS OF AGE AND OLDER: 0.1 to 0.2 mL 3 times daily in enteric coated capsules.

Clinical Effects

Summary Of Exposure

    A) USES: Peppermint oil is used primarily as a flavoring and aromatic in a wide variety of products. As an alternative medicine, it has been used as an antispasmodic, an antiseptic, and as an anti-HSV1 and anti-HSV2 antiviral. Additionally, peppermint oil has been used to treat cramps, dyspepsia, nausea, the common cold, sore throat, and to relieve symptoms of irritable bowel syndrome and tension headaches. It may also be used topically to treat myalgia and neuralgia.
    B) PHARMACOLOGY: Menthol, the major constituent of peppermint oil, blocks calcium channels causing smooth muscle relaxation.
    C) TOXICOLOGY: Toxicity following overdose is due to the actions of menthol.
    D) EPIDEMIOLOGY: Overdose is rare.
    E) WITH POISONING/EXPOSURE
    1) Reported cases of menthol toxicity are rare. The most commonly reported symptoms are ataxia, confusion, coma, nausea, and vomiting. Animals have developed CNS depression, ataxia, seizures, and coma.

Heent

    3.4.3) EYES
    A) SPLASH CONTACT caused loss of corneal epithelium, corneal infiltration, release of pigment into the anterior chamber with deposits on the back of the cornea. The irritation subsided in 16 days (HSDB , 2001; Grant & Schuman, 1993).
    B) DIPLOPIA: CASE REPORT: A 13-year-old boy with a history of asthma developed diplopia and nystagmus after intentionally inhaling approximately 200 mg of menthol contained in 5 mL of olbas oil as treatment for nasal inflammation. He recovered fully 12 hours after hospital admission (O'Mullane et al, 1982).
    3.4.5) NOSE
    A) IRRITATION: When a 5% solution of menthol was applied to the nasal mucous membranes for 9 months, destructive changes were seen in all layers of the nasal membranes. Some of these changes were seen even with a 1% solution (Fox, 1930).
    B) HYPOSMIA: Occupational hyposmia is found in workers exposed to menthol in their working environment (Naus, 1968).
    3.4.6) THROAT
    A) HYPERSENSITIVITY: Allergic reactions of the mouth and neck have been described in patients using peppermint toothpaste (Papa & Shelley, 1964).
    B) ASPHYXIATION: Epiglottal spasm and asphyxiation has been reported in infants following inhalation of menthol-containing nasal drops.

Cardiovascular

    3.5.2) CLINICAL EFFECTS
    A) ATRIAL FIBRILLATION
    1) WITH POISONING/EXPOSURE
    a) CASE REPORT: Idiopathic atrial fibrillation was reported in 2 patients following chronic consumption of large amounts of peppermint candy (Thomas, 1962).
    B) BRADYCARDIA
    1) WITH POISONING/EXPOSURE
    a) Bradycardia has been reported (S Sweetman , 2000; Luke, 1962).

Respiratory

    3.6.2) CLINICAL EFFECTS
    A) RESPIRATORY FINDING
    1) WITH THERAPEUTIC USE
    a) Peppermint oil may potentially cause bronchospasm, tongue spasm and respiratory arrest when taken internally or used near the face in infants and young children . The authors suggest, however, that the amount of peppermint found in over-the-counter products (eg, cough and cold medications, herbal teas and topical preparations) is likely safe in pregnant and lactating women and young children (Kligler & Chaudhary, 2007).
    B) APNEA
    1) WITH POISONING/EXPOSURE
    a) CASE REPORT: An infant was erroneously administered Karvol capsules, containing menthol and pine oil, into his nose. Difficult breathing developed and respiratory arrest occurred on admission to the ED. The infant was intubated and recovered, being discharged 72 hr later (Blake, 1993).
    C) ACUTE LUNG INJURY
    1) WITH POISONING/EXPOSURE
    a) CASE REPORT: A pregnant 18-year-old woman was found unconscious, cyanotic, and in respiratory distress after self-injecting 5 mL of peppermint oil intravenously. Within 2 hours post-exposure, the patient developed alveolar edema and became hypoxemic, necessitating intubation and mechanical ventilation for 10 days. A chest CT scan showed bilateral interstitial and alveolar infiltrates and a bronchoscopy revealed hemorrhagic secretions in all segments and erythematous mucous membranes, although there was no evidence of aspiration. She was lost to follow up and outcome of the fetus is unknown (Behrends et al, 2005).

Neurologic

    3.7.2) CLINICAL EFFECTS
    A) CENTRAL NERVOUS SYSTEM DEFICIT
    1) WITH POISONING/EXPOSURE
    a) CASE REPORT: A13-year-old boy with a history of asthma intentionally inhaled approximately 200 mg of menthol contained in 5 mL of olbas oil as treatment for nasal inflammation. He was found at home minimally responsive and speaking nonsense. Ataxia and weakness to the left arm and leg were noted upon initial examination. He was admitted to the hospital with stable vital signs and no limb weakness but persistent ataxia. Nystagmus was observed and he reported diplopia. Additionally, he was observed to be euphoric. He recovered completely within 12 hours of admission (O'Mullane et al, 1982).
    B) COMA
    1) WITH POISONING/EXPOSURE
    a) Drowsiness, ataxia, and coma may occur, and have been seen in animals (HSDB , 2001; Gosselin et al, 1984; Luke, 1962).
    C) DIZZINESS
    1) WITH POISONING/EXPOSURE
    a) Dizziness and ataxia may be noted (Eickholt & Box, 1965) and have been seen in animal experiments.
    D) SEIZURE
    1) WITH POISONING/EXPOSURE
    a) Muscle twitching, tremor and seizures have been described in animals (HSDB , 2001; S Sweetman , 2000; Gosselin et al, 1984).
    E) HEADACHE
    1) WITH THERAPEUTIC USE
    a) Headache has been reported as an adverse effect (S Sweetman , 2000).
    3.7.3) ANIMAL EFFECTS
    A) ANIMAL STUDIES
    1) NEUROPATHY
    a) RATS given 100 mg/kg/day for 28 days developed brain lesions which were similar to those associated with hexachlorophene-induced neuropathy (Olsen & Thorup, 1984).

Gastrointestinal

    3.8.2) CLINICAL EFFECTS
    A) INDIGESTION
    1) WITH THERAPEUTIC USE
    a) Heartburn and gastrointestinal reflux may occur with small doses (Kligler & Chaudhary, 2007; S Sweetman , 2000; Gosselin et al, 1984; Luke, 1962).
    B) NAUSEA AND VOMITING
    1) WITH POISONING/EXPOSURE
    a) Common adverse effects may produce nausea, vomiting, heartburn and perianal burning (Kligler & Chaudhary, 2007).
    C) GASTROESOPHAGEAL REFLUX DISEASE
    1) WITH THERAPEUTIC USE
    a) Peppermint oil can lower the esophageal sphincter tone leading to gastroesophageal reflux; therefore, it is contraindicated in individuals with a history of hiatal hernia or a significant history of reflux. It may exacerbate symptoms (Kligler & Chaudhary, 2007).
    3.8.3) ANIMAL EFFECTS
    A) ANIMAL STUDIES
    1) Peppermint oil inhibits gastrointestinal smooth muscle in laboratory animals (Taylor et al, 1983) and in man (Sigmund & McNally, 1969).

Hepatic

    3.9.2) CLINICAL EFFECTS
    A) JAUNDICE
    1) WITH POISONING/EXPOSURE
    a) CASE SERIES: Multiple cases of jaundice were reported in glucose-6-phosphate dehydrogenase deficient babies exposed to a mentholated powder applied to their umbilical cords. It was postulated that the jaundice was due to an inability of these babies to conjugate the menthol (Olowe & Ransome-Kuti, 1980).

Genitourinary

    3.10.2) CLINICAL EFFECTS
    A) IMPAIRED RENAL FUNCTION DISORDER
    1) WITH POISONING/EXPOSURE
    a) There have been rare reports of interstitial nephritis and acute renal failure with peppermint oil exposure (Kligler & Chaudhary, 2007).

Dermatologic

    3.14.2) CLINICAL EFFECTS
    A) CHEMICAL BURN
    1) WITH THERAPEUTIC USE
    a) Skin irritation and severe chemical burns have resulted from topical use (Parys, 1983).
    b) Severe skin necrosis has been described in a patient who applied a topical methyl salicylate and menthol ointment followed by use of a heating pad (Heng, 1987).
    B) DERMATITIS
    1) WITH THERAPEUTIC USE
    a) Contact dermatitis and urticaria may be noted in sensitive individuals (Papa & Shelley, 1964; Rudzki et al, 1976; Mazaki et al, 1948; McGowan, 1966; S Sweetman , 2000).
    C) PURPURA
    1) WITH POISONING/EXPOSURE
    a) CASE REPORT: Nonthrombocytopenic purpura was seen in a 36 year old woman who used mentholated cigarettes (Highstein & Zeligman, 1951).

Musculoskeletal

    3.15.2) CLINICAL EFFECTS
    A) MUSCLE PAIN
    1) WITH POISONING/EXPOSURE
    a) Recurrent muscle aches and pains ("palindromic rheumatism") occurred in 2 patients consuming large amounts of peppermint candy chronically (Williams, 1972).
    B) INCREASED MUSCLE TONE
    1) WITH POISONING/EXPOSURE
    a) Muscle rigidity which persisted for days was reported (Luke, 1962).
    C) MUSCLE WEAKNESS
    1) WITH POISONING/EXPOSURE
    a) A 13-year-old boy with a history of asthma developed ataxia and weakness to the left arm and leg after intentionally inhaling approximately 200 mg of menthol contained in 5 mL of olbas oil as treatment for nasal inflammation. He recovered fully 12 hours after hospital admission (O'Mullane et al, 1982).

Immunologic

    3.19.2) CLINICAL EFFECTS
    A) ACUTE ALLERGIC REACTION
    1) WITH THERAPEUTIC USE
    a) In clinical trials, allergic reactions were a common adverse event (Kligler & Chaudhary, 2007).
    b) Allergic reactions of the mouth and neck have been described in patients using peppermint toothpaste (Papa & Shelley, 1964).

Reproductive

    3.20.1) SUMMARY
    A) Peppermint oil has been used to induce menstruation and should, therefore, be avoided in pregnancy.
    3.20.3) EFFECTS IN PREGNANCY
    A) USE IN PREGNANCY
    1) Peppermint oil has been used to induce menstruation and should, therefore, be avoided in pregnancy (Kligler & Chaudhary, 2007). The authors, however, suggest that the amount of peppermint found in over-the-counter products (eg, cough and cold medications, topical preparations and herbal teas) is likely safe in pregnant women.
    3.20.4) EFFECTS DURING BREAST-FEEDING
    A) LACK OF INFORMATION
    1) There is currently insufficient evidence to determine the safety of peppermint oil during lactation. The authors, however, suggest that the amount of peppermint found in over-the-counter products (eg, cough and cold medications, topical preparations and herbal teas) is likely safe in lactating women (Kligler & Chaudhary, 2007).

Laboratory Monitoring

Monitoring Parameters Levels

    4.1.1) SUMMARY
    A) Routine laboratory monitoring is not necessary unless otherwise clinically indicated.
    B) Monitor vital signs and mental status.
    C) Obtain a chest x-ray if aspiration is suspected.
    4.1.2) SERUM/BLOOD
    A) Routine laboratory monitoring is not necessary unless otherwise clinically indicated.
    4.1.4) OTHER
    A) OTHER
    1) MONITORING
    a) Monitor vital signs and mental status.

Radiographic Studies

    A) Obtain a chest x-ray if aspiration is suspected.

Methods

    A) CHROMATOGRAPHY
    1) Various methods are available, including a gas-liquid chromatography assay (Bell et al, 1981).

Treatment

Life Support

    A) Support respiratory and cardiovascular function.

Patient Disposition

    6.3.1) DISPOSITION/ORAL EXPOSURE
    6.3.1.1) ADMISSION CRITERIA/ORAL
    A) Patients with persistent CNS depression or respiratory distress should be admitted.
    6.3.1.2) HOME CRITERIA/ORAL
    A) Patients with inadvertent exposures who have only minor GI irritation may be observed at home.
    6.3.1.3) CONSULT CRITERIA/ORAL
    A) Consult a medical toxicologist or poison center for patients with severe toxicity.
    6.3.1.5) OBSERVATION CRITERIA/ORAL
    A) Patients with any CNS depression, severe GI irritation, or deliberate ingestion should be referred to a healthcare facility.

Monitoring

    A) Routine laboratory monitoring is not necessary unless otherwise clinically indicated.
    B) Monitor vital signs and mental status.
    C) Obtain a chest x-ray if aspiration is suspected.

Oral Exposure

    6.5.1) PREVENTION OF ABSORPTION/PREHOSPITAL
    A) Gastrointestinal decontamination is not generally indicated.
    6.5.2) PREVENTION OF ABSORPTION
    A) SUMMARY: Gastrointestinal decontamination is not generally indicated. However, activated charcoal may be considered for recent, large, deliberate ingestions if the patient is alert or airway is protected.
    B) ACTIVATED CHARCOAL
    1) CHARCOAL ADMINISTRATION
    a) Consider administration of activated charcoal after a potentially toxic ingestion (Chyka et al, 2005). Administer charcoal as an aqueous slurry; most effective when administered within one hour of ingestion.
    2) CHARCOAL DOSE
    a) Use a minimum of 240 milliliters of water per 30 grams charcoal (FDA, 1985). Optimum dose not established; usual dose is 25 to 100 grams in adults and adolescents; 25 to 50 grams in children aged 1 to 12 years (or 0.5 to 1 gram/kilogram body weight) ; and 0.5 to 1 gram/kilogram in infants up to 1 year old (Chyka et al, 2005).
    1) Routine use of a cathartic with activated charcoal is NOT recommended as there is no evidence that cathartics reduce drug absorption and cathartics are known to cause adverse effects such as nausea, vomiting, abdominal cramps, electrolyte imbalances and occasionally hypotension (None Listed, 2004).
    b) ADVERSE EFFECTS/CONTRAINDICATIONS
    1) Complications: emesis, aspiration (Chyka et al, 2005). Aspiration may be complicated by acute respiratory failure, ARDS, bronchiolitis obliterans or chronic lung disease (Golej et al, 2001; Graff et al, 2002; Pollack et al, 1981; Harris & Filandrinos, 1993; Elliot et al, 1989; Rau et al, 1988; Golej et al, 2001; Graff et al, 2002). Refer to the ACTIVATED CHARCOAL/TREATMENT management for further information.
    2) Contraindications: unprotected airway (increases risk/severity of aspiration) , nonfunctioning gastrointestinal tract, uncontrolled vomiting, and ingestion of most hydrocarbons (Chyka et al, 2005).
    6.5.3) TREATMENT
    A) SUPPORT
    1) Treatment is symptomatic and supportive.
    B) MONITORING OF PATIENT
    1) Routine laboratory monitoring is not necessary unless otherwise clinically indicated.
    2) Monitor vital signs and mental status.
    3) Consider a chest x-ray if aspiration is suspected.
    C) AIRWAY MANAGEMENT
    1) Ensure adequate ventilation and perform endotracheal intubation early in patients with significant CNS or respiratory depression.

Range Of Toxicity

Summary

    A) TOXICITY: A specific toxic dose has not been established. Apnea, cyanosis, and respiratory arrest occurred in an infant after direct application of menthol to the nares. A 13-year-old boy experienced CNS depression, vertigo, and ataxia after inhaling 200 mg of menthol.
    B) THERAPEUTIC DOSE: There is no well-established therapeutic dose. ADULT: ORAL CAPSULE: 0.2 to 0.4 mL 3 times daily in enteric coated capsules. INHALATION: 3 to 4 drops in hot water. OIL (INTERNAL): 6 to 12 drops daily. THROAT LOZENGE: Throat lozenges contain 5 to 10 mg of menthol and have not been associated with significant toxicity. PEDIATRIC: CHILDREN 8 YEARS OF AGE AND OLDER: 0.1 to 0.2 mL 3 times daily in enteric coated capsules.

Therapeutic Dose

    7.2.1) ADULT
    A) GENERAL
    1) CAPSULES - 0.2 to 0.4 milliliters three times daily administered in enteric coated capsules has been used in the treatment of irritable bowel syndrome (Kligler & Chaudhary, 2007; Rees et al, 1979).
    2) OIL (Internal) - Average daily dosage is 6 to 12 drops (Blumenthal et al, 1998)
    a) INHALATION: 3 to 4 drops in hot water
    b) IRRITABLE COLON (ORAL): Average single dose is 0.2 milliliter; average daily dose is 0.6 milliliter in enterically coated form.
    3) OIL (Topical) - A few drops rubbed in the affected skin areas (Blumenthal et al, 1998).
    4) Acceptable daily intake (ADI) for menthol, as a food additive, is 0 to 4 milligrams/kg (WHO, 1999).
    5) DYSPEPSIA - In clinical trials, a prepared dose of a 90 mg of peppermint oil combined with 50 mg of caraway oil have been used to treat dyspepsia. The preparation is not currently available in the United States (Kligler & Chaudhary, 2007).
    7.2.2) PEDIATRIC
    A) ENTERIC-COATED CAPSULES
    1) Children 8 years of age and older: 0.1 to 0.2 mL three times daily (Kligler & Chaudhary, 2007)
    2) In a single clinical trial, 0.1 mL three times daily was given to children weighing less than 45 kg to treat irritable bowel syndrome (Kligler & Chaudhary, 2007).

Maximum Tolerated Exposure

    A) COUGH LOZENGES: Over-the-counter antitussive lozenges containing 5 to 10 mg of menthol are considered to present a low risk for acute toxicity (FDA, 1990).
    B) CASE REPORT: A pregnant 18-year-old woman was found unconscious, cyanotic, and in respiratory distress after intentionally self-injecting 5 mL of peppermint oil IV. Within 2 hours post-exposure, the patient developed alveolar edema and became hypoxemic, necessitating intubation and mechanical ventilation. She was treated with aggressive supportive care, required intubation for 10 days, and was discharged 15 days post-exposure. Fetal outcome is not known (Behrends et al, 2005).
    C) CASE REPORT: A13-year-old boy with a history of asthma intentionally inhaled approximately 200 mg of menthol contained in 5 mL of olbas oil as treatment for nasal inflammation. He was found at home minimally responsive and speaking nonsense. Ataxia and weakness to the left arm and leg were noted upon initial examination. He was admitted to the hospital with stable vital signs and no limb weakness but persistent ataxia. Nystagmus was observed and he reported diplopia. Additionally, he was observed to be euphoric. He recovered completely within 12 hours of admission (O'Mullane et al, 1982).
    D) CASE REPORT: An infant was erroneously administered Karvol capsules, containing menthol and pine oil, into his nose. Difficult breathing developed and respiratory arrest occurred on admission to the ED. The infant was intubated and recovered, being discharged 72 hr later (Blake, 1993).

Toxicity Information

    7.7.1) TOXICITY VALUES
    A) MENTHOL
    1) LD50- (ORAL)MOUSE:
    a) 3000 to 4000 mg/kg depending on which isomer was used (Wokes, 1932)
    2) LD50- (INTRAMUSCULAR)RAT:
    a) 10 g/kg (Lewis, 2000)
    3) LD50- (INTRAPERITONEAL)RAT:
    a) 819 mg/kg (Eickholt & Box, 1965)
    4) LD50- (ORAL)RAT:
    a) 3180 mg/kg (Lewis, 2000)
    B) PEPPERMINT OIL
    1) LD50- (ORAL)MOUSE:
    a) 2490 mg/kg (RTECS, 2001)
    2) LD50- (INTRAPERITONEAL)RAT:
    a) 819 mg/kg (RTECS, 2001)
    3) LD50- (ORAL)RAT:
    a) 2426 mg/kg (RTECS, 2001)

Pharmacology Toxicology

Pharmacologic Mechanism

    A) Menthol, the major constituent of peppermint oil blocks calcium channels causing smooth muscle relaxation.
    B) ANTIBACTERIAL
    1) Like many volatile oils, peppermint oil (containing menthol) has mild to moderate bactericidal properties (Wokes, 1932).
    C) SPASMOLYTIC
    1) Menthol is the primary constituent of peppermint oil that causes a relaxant activity on gastrointestinal smooth muscle. This effect is related to menthol's ability to reduce the influx of extracellular calcium ions through potential dependent calcium channels (Taylor et al, 1985)(Rogers et al, 1988). The exact mechanism and effect is still unclear, since data from other studies are contradictory (Rogers et al, 1988).
    2) Peppermint containing drugs appear to have an effective use in the treatment of irritable bowel and abdominal pain (Rees et al, 1979).
    D) ANIMAL STUDIES
    1) ANTI-INFLAMMATORY: Aznlene, one of constituents found in small quantities in peppermint oil, has been shown to have anti-inflammatory and antiulcerogenic effects when tested in animals (Anon, 1990).
    2) BILE STIMULATION: Experiments in dogs have shown bile stimulating effects. Similar effects were seen in guinea pigs given 0.1 to 50 mg/kg (Giachetti, 1988).

Toxicologic Mechanism

    A) IRRITANT EFFECT
    1) Menthone is a strong irritant and responsible for skin irritation due to peppermint oil (Mazaki et al, 1948). Peppermint oil consists of menthol 50 to 78%, menthone 25 to 30% and other menthol esters (Parys, 1983; Tyler et al, 1988).

Physicochemical

Physical Characteristics

    A) Peppermint oil is a pale yellow colorless, or greenish-yellow liquid with the odor and pungent taste of peppermint (HSDB , 2001; S Sweetman , 2000).

Molecular Weight

    A) Not available

References

General Bibliography

    1) Anon: Peppermint. The Lawrence Review of Nat Prod (Jul), 1990.
    2) Behrends M, Beiderlinden M, & Peters J: Acute lung injury after peppermint oil injection. Anesth Analg 2005; 101(4):1160-1162.
    3) Bell GD, Henry DA, & Richmond CR: A specific g.l.c. assay for menthol in urine. Br J Clin Pharmacol 1981; 12:281.
    4) Blake KD: Dangers of common cold treatments in children (letter). Lancet 1993; 341:640.
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