Peppermint Oil : Safety

by MedlinePlus

(Page 2 of 2)

Allergies

Allergic/hypersensitivity reactions may occur from using peppermint or menthol by mouth or on the skin, including throat closing (laryngeal spasm), breathing problems (bronchial constriction/asthma symptoms), or skin rash/hives/contact dermatitis. People with known allergy/hypersensitivity to peppermint leaf or oil should avoid peppermint products.

Side Effects and Warnings

Peppermint is generally regarded as being safe in non-allergic adults when taken in small doses, for example as tea.

Peppermint oil may be safe in small doses, although multiple adverse effects are possible. When used on the skin, peppermint oil has been associated with allergic/hypersensitivity reactions, skin rash/hives/contact dermatitis, mouth ulcers/sores, and eye irritation. Peppermint oil taken by mouth may cause headache, dizziness, heartburn, anal burning, slow heart rate, or muscle tremor. Mouth sores may occur with peppermint oil-containing mouthwashes. There is report of asthma symptoms related to a mint-flavored toothpaste. Very large doses of peppermint oil taken by mouth in animals have resulted in muscle weakness, brain damage, and seizure. Peppermint oil should be used cautiously by people with G6PD deficiency (based on reports of jaundice in babies exposed to menthol) or gallbladder disease (gallstones, bile duct obstruction). Enteric-coated tablets have been recommended in those with hiatal hernia or heartburn/gastroesophageal reflux disease (GERD), over other dosage forms. Use in infants or children is discouraged due to potential toxicity, including when inhaled, taken by mouth, or used on the skin around the facial area.

Menthol, a constituent of peppermint oil that is included in mouthwashes, toothpastes, mentholated cigarettes, and decongestant "rubs" or lozenges, has been associated with multiple adverse effects. Although small amounts may be safe in non-allergic adults, doses over 1 gram per kilogram of body weight may be deadly in humans, and toxic doses can be absorbed through the skin (and may be increased with local application of heat, such as with a heating pad). Serious breathing difficulties or triggering of asthma symptoms may occur with menthol use near the nose or on the chest. Mouth sores have been associated with use of mint-flavored toothpaste, mouthwash, or mentholated cigarettes. Mentholated cigarettes have been linked with skin bruising (purpura), although the exact cause has nit been proven. Use on the skin of menthol or methyl salicylate (also a peppermint oil constituent) has rarely been associated with rash, severe skin damage (necrosis), or kidney damage (interstitial nephritis). Inhalation of large doses of menthol may lead to dizziness, confusion, muscle weakness, nausea, or double vision. High doses of menthol have caused brain damage in animal studies.

Pregnancy and Breastfeeding

Peppermint oil and menthol should be avoided during pregnancy and breastfeeding due to insufficient information and potential for toxicity.

Interactions

Interactions with Drugs

There is a preliminary report that taking peppermint oil by mouth may increase blood levels of the drugs felodipine (Plendil®) and simvastatin (Zocor®). In rats, peppermint oil increases levels of cyclosporine in the blood, although effects in humans are not clear. Based on rat research, peppermint oil used on the skin with 5-fluorouracil (5-FU) may increase the rate of absorption of 5-FU.

Based on laboratory studies, peppermint oil may interfere with the way the body processes certain drugs using the liver's "cytochrome P450" enzyme system. As a result, the levels of these drugs may be increased in the blood, and may cause increased effects or potentially serious adverse reactions. If you are using any medications, check the package insert and speak with your healthcare provider or pharmacist about possible interactions.

Interactions with Herbs and Supplements

Based on laboratory studies, peppermint oil may interfere with the way the body processes certain herbs or supplements using the liver's "cytochrome P450" enzyme system. As a result, the levels of other herbs or supplements to be too high in the blood. It may also alter the effects that other herbs or supplements possibly have on the P450 system, such as bloodroot, cat's claw, chamomile, chaparral, chasteberry, damiana, Echinacea angustifolia, goldenseal, grapefruit juice, licorice, oregano, red clover, St. John's wort, wild cherry, and yucca. If you are using any medications, check the package insert and speak with your healthcare provider or pharmacist about possible interactions.

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