Peppermint Oil

by MedlinePlus

Peppermint is a perennial flowering plant that grows throughout Europe and North America. Peppermint is widely cultivated for its fragrant oil, which is obtained through steam distillation of the fresh above-ground parts of the plant. Peppermint oil has been used historically for numerous health conditions, including common cold symptoms, cramps, headache, indigestion, joint pain, and nausea. Peppermint leaf has been used for stomach/intestinal disorders and for gallbladder disease.

Mint plants such as peppermint and spearmint have a long history of medicinal use, dating to ancient Egypt, Greece, and Rome. The scientific name for peppermint (Mentha x piperita) is derived from the name Mintha, a Greek mythological nymph who transformed herself into the plant, and from the Latin piper meaning "pepper." Peppermint is believed to be a cross (hybrid) between spearmint and water mint that arose naturally.

Peppermint oil is available in bulk herb oil, enteric-coated capsules, soft gelatin capsules, and in liquid form. In small doses such as in tea or chewing gum, peppermint is generally believed to be safe in healthy, non-pregnant, non-allergic adults. The United States is a principal producer of peppermint, and the largest markets for peppermint oil are manufacturers of chewing gum, toothpaste, mouthwash, and pharmaceuticals.

Evidence

These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.

Uses based on scientific evidence

Indigestion (non-ulcer dyspepsia)

There is preliminary evidence from a small number of controlled trials that a combination of peppermint oil and caraway oil may be beneficial for dyspepsia (heartburn) symptoms. However, most studies have been poorly designed (methodologically weak with small sample sizes, inadequate use of control or placebo groups, unclear descriptions of blinding and randomization, and lack of use of standardized scales for identifying subjects or assessing endpoints). It is not clear which constituent(s) may be beneficial. Nonetheless, the existing evidence does suggest efficacy of this combination. It should be noted that heartburn can actually be a side effect of taking oral peppermint oil, which has been reported by patients in several controlled trials of peppermint oil. Patients with chronic heartburn should be evaluated by a qualified healthcare provider and may be advised to undergo a diagnostic endoscopy prior to initiating any treatment for heartburn.

Irritable bowel syndrome (IBS)

Multiple randomized controlled trials of peppermint suggest significant improvements in irritable bowl syndrome (IBS) symptoms. Although the mechanism of action is not clear, pre-clinical studies suggest smooth muscle relaxing properties of peppermint (calcium antagonism may play a role). Enteric-coated peppermint preparations are generally recommended. Overall, studies have been brief with small sample sizes and methodological weaknesses (unclear diagnostic criteria, lack of validated measurement scales, unclear blinding and randomization procedures). Well-designed large trials are necessary before a strong recommendation can be made. Future studies should use standardized symptom scales and established diagnostic criteria to classify patients proir to enrollment (such as Rome II Diagnostic Criteria), uniform dosing and standardization, and longer duration.

Antispasmodic (gastric spasm)

One study reports that peppermint oil solution administered intraluminally can be used as an antispasmodic agent with superior efficacy and fewer side effects than hyoscine-N-butylbromide administered by intramuscular injection during upper endoscopy.

Tension headache

Application of diluted peppermint oil to the forehead and temples has been tested in people with headache. Studies have not been well conducted, and it is not clear if this is an effective treatment.

Nausea

Due to limited human study, there is not enough evidence to recommend for or against the use of peppermint oil in the treatment of nausea. Further research is needed before a recommendation can be made.

Nasal congestion

Menthol, a constituent of peppermint oil, is sometimes included in inhaled preparations for nasal congestion, including "rubs" that are applied to the skin and inhaled. Early research suggests that the nose breathing may be improved, although it is not clear if there are true benefits on breathing or nasal congestion. High quality research is lacking in this area.

Urinary tract infection

There is limited study of peppermint tea added to other therapies for urinary tract infections. It is not clear if this is an effective treatment, and it is not recommended to rely on peppermint tea alone to treat this condition.

Uses based on tradition or theory

The below uses are based on tradition or scientific theories. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.

Antacid, anorexia, antiviral, arthritis, asthma, bile duct disorders, bronchial spasm, cancer, chicken pox, cholelithiasis (gallstones), colonic spasm (during colonoscopy or barium enema), common cold, cough, cramps, dysmenorrhea (menstrual pain), enteritis, fever, fibromyositis, gallbladder disorders, gas (flatulence), gastrointestinal disorders, gastritis, gonorrhea, head lice (Pediculus humanus capitus), ileus (post-operative), inflammation of oral mucosa, influenza, intestinal colic, laryngeal spasm, local anesthetic, morning sickness, motility disorders, mouthwash, musculoskeletal pain, myalgia (muscle pain), neuralgia (nerve pain), postherpetic neuralgia, pruritus (itching), rheumatic pain, sun block, tendonitis, toothache, tuberculosis, urticaria (hives).

Dosing

The below doses are based on scientific research, publications, traditional use, or expert opinion. Many herbs and supplements have not been thoroughly tested, and safety and effectiveness may not be proven. Brands may be made differently, with variable ingredients, even within the same brand. The below doses may not apply to all products. You should read product labels, and discuss doses with a qualified healthcare provider before starting therapy.

Adults (18 years and older)

Peppermint oil: Peppermint oil should be used cautiously, as doses of the constituent menthol over 1 gram per kilogram of body weight may be deadly. For intestinal/digestion disorders, doses of 0.2 to 0.4 milliliters of peppermint oil in enteric-coated capsules, dilute preparations, or suspensions taken three times daily by mouth have been used or studied. Lozenges containing 2 to 10 milligrams of peppermint oil have been used. 10% peppermint oil (in methanol) has been applied to the skin (forehead and temples) multiple times per day for headache relief. Some sources recommend using peppermint oil preparations on the skin no more than 3 to 4 times per day, although reliable safety information is limited in this area. For inhalation, 3 to 4 drops of oil added to 150 milliliters of hot water and inhaled up to three times per day or 1% to 5% essential oil as a nasal ointment has been used to relieve congestion. Enteric coated peppermint oil capsules may be better tolerated than other dosage forms.

Peppermint leaf: There is limited study of the safety/effectiveness of peppermint leaf preparations, and doses are based on traditional use or anecdote. As an infusion, 3 to 6 grams of peppermint leaf has been used daily. Doses of other liquid preparations depend on concentration, for example, 2 to 3 milliliters of tincture (1:5 in 45% ethanol) three times daily, or 1 milliliter of spirits (10% oil and 1% leaf extract, mixed with water) has been taken. Various doses of dried herb extract have been noted traditionally, ranging from 0.8 grams daily up to 4 grams taken three times daily, although safety is not clear.

Children (younger than 18 years)

There is not enough scientific information available to recommend the safe use of peppermint leaf or oil in children.

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