Peppermint Oil in pregnancy and breastfeeding

What NCCIH says about safety

Peppermint oil appears to be safe when taken orally (by mouth) or applied topically in the doses commonly used. Peppermint oil has been safely used in multiple clinical trials. Possible side effects of peppermint oil taken orally include heartburn, nausea, abdominal pain, and dry mouth. Rarely, peppermint oil can cause allergic reactions. Capsules containing peppermint oil are often enteric-coated to reduce the likelihood of heartburn. Peppermint oil is possibly safe when inhaled as aromatherapy, but there is not enough reliable information to know if it is safe or what the side effects might be if applied topically into the nose. Side effects of applying peppermint oil to the skin can include skin rashes and irritation. Peppermint oil should not be applied to the face of infants or young children because serious side effects may occur if they inhale the menthol in the oil. Peppermint tea, which is made from peppermint leaves, appears to be safe. However, the long-term safety of consuming large amounts of peppermint leaf is unknown. Use of oral peppermint in amounts commonly found in food is likely safe during pregnancy or while breastfeeding, but little is known about whether it’s safe to use oral peppermint in medicinal amounts during pregnancy or while breastfeeding.

Quoted in full from NCCIH so nothing is lost in summarising. Where they say “little is known”, that means the studies do not exist — not that the herb is known to be safe, and not that it is known to be harmful.

How much is actually known

A small amount of research has been conducted on peppermint oil, primarily focusing on IBS. Very little research has been done on peppermint leaf. There is not enough evidence to definitely determine whether peppermint leaf is useful for any health condition.

What the research has found

A small amount of research suggests that peppermint oil in enteric-coated capsules may improve IBS symptoms in adults. A 2022 review of 10 studies (involving 1,030 participants) found that peppermint oil was better than placebo at improving overall IBS symptoms and reducing abdominal pain but caused more side effects than placebo. Most of the side effects were mild and included acid reflux and indigestion. A 2021 clinical guideline from the American College of Gastroenterology recommended the use of peppermint oil for relief of overall IBS symptoms and noted that enteric-coated formulations might help with acid reflux and indigestion side effects. A small amount of research suggests that taking peppermint extract by mouth or inhaling peppermint oil can help reduce nausea and vomiting in people undergoing chemotherapy treatment for cancer. A 2024 review of 10 studies on aromatherapy, which included 4 studies (involving 290 participants) on peppermint oil, found that inhaling peppermint oil was particularly successful at reducing nausea and vomiting in patients with cancer who were undergoing chemotherapy. A few studies have indicated that specific products containing peppermint oil plus caraway oil and specific combination products that include peppermint leaves may help relieve indigestion. But there isn’t any evidence showing that taking peppermint oil alone can help. In fact, peppermint oil taken alone may worsen indigestion in some people and cause unwanted side effects. A limited amount of evidence suggests that peppermint oil applied topically (on the skin) might relieve tension headaches, and that a gel containing peppermint oil applied topically might reduce the risk of bed sores (pressure ulcers) in bedridden individuals. Peppermint oil in a gel, water, or cream applied topically to the nipple area of breastfeeding women might be helpful for reducing pain and cracked skin. Menthol, which is in peppermint oil, should not be inhaled by or applied to the face of an infant or small child because it may negatively affect their breathing. Peppermint oil should therefore be used only after breastfeeding and then wiped off before the next breastfeeding session. A small amount of research suggests that peppermint oil might be helpful to reduce spasms during certain procedures, such as endoscopy or barium enema examination. There’s not enough evidence to allow any conclusions to be reached about whether peppermint oil is helpful for other conditions.

Before you take this

Dose and form change the answer completely. A culinary amount of a spice, a cup of tea, and a concentrated supplement extract are three different things, and most research is done on the last of them.

Supplements are also not regulated like medicines, so strength and purity vary between products. Bring the actual bottle to your midwife, doctor or pharmacist — that conversation is worth more than any page, including this one.