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.
Side effects of peppermint oil
These side effects of peppermint oil are usually mild and do not affect everyone. There are things you can do to help cope with them:
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're taking peppermint oil.
Itching or irritation around your bottom (anus)
Ask a pharmacist to recommend a cream if it bothers you.
Tell your doctor if this does not go away.
Headaches
Make sure you rest and drink plenty of fluids. It's best not to drink alcohol.
Painkillers you can buy without a prescription, such as paracetamol and ibuprofen, are safe to take with peppermint oil. Speak to your doctor if these do not help or the headaches are severe.
Keep taking peppermint oil, but talk to your doctor or pharmacist if the advice on how to cope does not help and a side effect is still bothering you or does not go away.
Serious side effects
It happens rarely, but some people may have a serious side effect when taking peppermint oil.
Stop taking peppermint oil and call your doctor or call 111 straight away if you:
- have an itchy and widespread skin rash
- have a slow heartbeat (bradycardia) – you may feel very tired or lightheaded
- have muscle shakes
- feel dizzy, which may also happen if you've had alcohol
Serious allergic reaction
In rare cases, it's possible to have a serious allergic reaction (anaphylaxis) to peppermint oil.
Immediate action required: Call 999 now if:
- your lips, mouth, throat or tongue suddenly become swollen
- you're breathing very fast or struggling to breathe (you may become very wheezy or feel like you're choking or gasping for air)
- your throat feels tight or you're struggling to swallow
- your skin, tongue or lips turn blue, grey or pale (if you have black or brown skin, this may be easier to see on the palms of your hands or soles of your feet)
- you suddenly become very confused, drowsy or dizzy
- someone faints and cannot be woken up
- a child is limp, floppy or not responding like they normally do (their head may fall to the side, backwards or forwards, or they may find it difficult to lift their head or focus on your face)
You or the person who's unwell may also have a rash that's swollen, raised, itchy, blistered or peeling.
These can be signs of a serious allergic reaction and may need immediate treatment in hospital.
Do not drive yourself to A&E.
The person you speak to at 999 will give you advice about what to do.
Other side effects
These are not all the side effects of peppermint oil. For a full list, see the leaflet inside your medicines packet.
Reporting side effects
You can report any suspected side effect using the Yellow Card safety scheme.
Visit the Yellow Card website for more information about reporting side effects.