context: Peppermint oil is derived from the peppermint plant -- a cross between water mint and spearmint -- that thrives in Europe and North America. Peppermint oil is commonly used as flavoring in foods and beverages and as a fragrance in soaps and cosmetics. Peppermint oil also is used for a variety of health conditions and can be taken orally in dietary supplements or topically as a skin cream or ointment. Clinical evidence suggests that peppermint oil likely can help with symptoms of irritable bowel syndrome. It may also help indigestion and prevent spasms in the GI tract caused by endoscopy or barium enema. Some studies show that used topically it may help sooth tension headaches and cracked nipples from breastfeedingâbut more research is needed to confirm these studies. When used as directed, dietary supplements and skin preparations containing peppermint oil are likely safe for most adults. Peppermint oil may cause side effects such as heartburn and it may interact with certain medications. Talk to your health care provider before using peppermint oil. In dietary supplements, peppermint oil has been tried for a variety of digestive problems including: Irritable bowel syndrome Indigestion Heartburn Dietary supplements containing peppermint oil are also used by some people for the following conditions, although there is no clear evidence that they are helpful: Nausea Vomiting Morning sickness Cramps of the upper gastrointestinal tract and bile ducts Diarrhea Gas Colds Coughs Inflammation of the mouth and throat Sinus and respiratory infections Menstrual problems Skin preparations containing peppermint oil are used by some people for the following conditions, although, again, there is no clear evidence that they are helpful: Headache Muscle pain Nerve pain Toothache Inflammation of the mouth Joint conditions Itchiness Allergic rash Repelling mosquitoes In addition, peppermint oil vapor is sometimes inhaled to treat symptoms of colds and coughs. Also, some doctors add peppermint oil to a barium solution to relax the colon during barium enemas. Several studies suggest that enteric-coated peppermint oil capsules -- which allow the oil to pass through the stomach so it can dissolve in the intestines -- may help relieve common symptoms of irritable bowel syndrome such as abdominal pain, bloating, and gas. Non-enteric coated forms of peppermint oil, however, actually may cause or worsen heartburn and nausea. Preliminary studies also suggest that dietary supplements containing a combination of peppermint oil and caraway oil may help relieve indigestion. In most adults, the small doses of peppermint oil contained in dietary supplements and skin preparations appear to be safe. Pregnant and breastfeeding women, however, should avoid such products because little is known about their safety during pregnancy and lactation. Possible side effects of peppermint oil include: Heartburn Allergic reactions such as flushing, headache, and mouth sores Anal burning during bouts of diarrhea Although enteric-coated peppermint oil capsules may reduce the risk of heartburn, their protective coating can break down more quickly and increase the risk of heartburn when taken at the same time as prescription and over-the-counter medications that decrease stomach acid and which are often used for heartburn or acid reflux. It's best to take such drugs at least two hours after taking enteric-coated peppermint oil products. A stomach condition called achlorhydria, in which the stomach doesn't produce hydrochloric acid, also may hasten the coating's breakdown. So people with the condition are advised against using peppermint oil. Before taking peppermint oil, discuss the risks and benefits with your health care provider. Some supplements can interact with medicine. Interactions can be harmful or make medications not work as they should. Be cautious about combining peppermint oil with certain drugs because it may inhibit the body's ability to metabolize the drugs and increase the risk of side effects.