Peppermint oil is a type of medicine called an antispasmodic. It helps relieve stomach cramps, bloating and farting (flatulence), particularly if you have irritable bowel syndrome (IBS). It works by helping the muscle of the bowel wall to relax.

Peppermint oil comes as capsules. It’s available on prescription or to buy from a pharmacy or a shop.

• The usual dose of peppermint oil is 1 or 2 capsules, taken 3 times a day. It’s best to take it around 1 hour before meals.
• Wait at least 2 hours between taking a dose of peppermint oil and taking an indigestion medicine. This allows the peppermint oil capsules to work properly.
• It will start to work within a few hours but it could take up to 1 to 2 weeks to take full effect. Keep taking peppermint oil until your symptoms improve.
• Common side effects include heartburn and indigestion.
• If you've bought peppermint oil from a pharmacy or shop, do not take it for longer than 2 weeks without checking with a doctor.

Most adults and children aged 12 and over can take peppermint oil capsules for irritable bowel syndrome (IBS). Some brands, however, are only suitable for those aged 15 years and above. Check the leaflet that comes with your medicine.

Peppermint oil is not suitable for some people. To make sure peppermint oil is safe for you, tell your pharmacist or doctor before starting it if you:

• have ever had an allergic reaction to peppermint oil or any other medicine
• have liver disease or gall stones
• weigh less than 40kg (around 6st 5lbs) or are losing weight
• are allergic to peanuts (some brands contain arachis oil, so it would be best to avoid those brands)
• are 40 or over and have IBS, but have not had an attack for a while
• have noticed that the symptoms you were taking peppermint oil for have changed
• have noticed blood when you poo
• have suffered abnormal vaginal bleeding or discharge
• difficulty or pain when peeing
• feel sick (nausea) or are being sick (vomiting)
• look paler than your usual skin tone, and feel tired
• recently had a high temperature
• are pregnant, or think you may be pregnant
• have digestive problems such as reflux disease, severe constipation or ulcerative colitis

Always follow the instructions that come with the capsules, or as advised by your doctor.

Swallow the capsules whole, with water. Do not break or chew them.

Dosage

The usual dose of peppermint oil for adults and children aged 12 and over is 1 capsule, taken 3 times a day until your symptoms get better. You can increase this to 2 capsules, taken 3 times a day, if 1 capsule has not helped your symptoms.

Do not take it for longer than 2 weeks unless prescribed by a doctor. Follow the doctor’s instructions.

When to take peppermint oil

Take peppermint oil capsules as and when you have symptoms.

It’s best to take peppermint oil around 1 hour before meals.

What if I forget to take it?

If you forget to take a dose, take it as soon as you remember, unless it's nearly time for the next dose. If that happens, just skip the missed dose and take the next one at the usual time.

Never take 2 doses at the same time. Never take an extra dose to make up for a forgotten one.

What if I take too much?

If you take 1 extra dose of peppermint oil, it's unlikely to harm you.

Speak to your pharmacist, doctor or call 111 if you're worried, or have taken 2 extra doses or more.

Like all medicines, peppermint oil can cause side effects in some people, but most people have no side effects or only minor ones.

Drinking alcohol while taking peppermint oil capsules can increase the chance of side effects. If this happens, it’s best not to drink alcohol.

Common side effects

These side effects happen in more than 1 in 100 people.

Talk to your doctor or pharmacist if these side effects bother you or do not go away:

• heartburn or indigestion
• itching or irritation around your anus (bottom)

Serious side effects

It happens rarely, but some people may have a serious side effect when taking peppermint oil.

Stop taking peppermint oil and speak to your doctor or call 111 if you:

• have an itchy and widespread skin rash
• have a slow heartbeat (bradycardia)
• have muscle shakes
• feel dizzy, which may also happen if you’ve had alcohol

What to do about:

• heartburn or indigestion – eat smaller, more frequent meals. Prop your head and shoulders up in bed, so stomach acid does not travel up towards your throat. If this lasts for more than a few days, speak to your doctor or a pharmacist and tell them that you are taking peppermint oil.
• itching or irritation around your anus – this is usually mild and only lasts a few days. Ask a pharmacist to recommend a cream if it bothers you. Tell your doctor if this does not go away after 1 week.

Peppermint oil is not usually recommended in pregnancy. This is because there is not enough information to say whether it’s safe or not. Your doctor will only recommend peppermint oil during pregnancy if the benefits outweigh the risks.

Peppermint oil and breastfeeding

Peppermint oil is OK to use in breastfeeding. If you notice that your baby is not feeding as well as usual, or if you have any other concerns about your baby, talk to your midwife, health visitor or doctor as soon as possible.

Some medicines may affect how peppermint oil works.

Do not take indigestion medicines up to 2 hours before or after you take peppermint oil capsules. These include:

• antacids
• omeprazole
• lansoprazole
• nizatidine
• famotidine

These can stop the peppermint oil working as it should.

Mixing peppermint oil with herbal remedies and supplements

Herbal medicines and supplements are not tested in the same way as other medicines. It’s not clear if it’s safe to take them with peppermint oil.