What is Pepto Bismol and what does it treat?
Pepto Bismol is a medicine used to treat heartburn, reflux, indigestion, diarrhoea, and nausea. Pepto Bismol contains the active ingredient bismuth subsalicylate. It works in the body by creating a protective barrier over the stomach, the lower part of the food pipe, and your gut. Pepto Bismol comes in both liquid form and tablet form.
Who is Pepto Bismol suitable for?
Pepto Bismol is suitable for adults and children aged 16 and over.
You should not take Pepto Bismol if you are allergic to bismuth subsalicylate or any of the other ingredients in Pepto Bismol.
You should not take Pepto Bismol if you are pregnant or breastfeeding.
Check with your GP or pharmacist before taking Pepto Bismol if:
- You are allergic to any medications
- You are allergic to amaranth
- You are diabetic
- You suffer from gout
- You cannot have aspartame
- You have a blood-clotting disorder
How to take Pepto Bismol
You should not take more than the recommended dose of Pepto Bismol. Always follow the patient leaflet or guidance from a healthcare professional.
For adults and children aged 16 and over
30ml of liquid OR two tablets every 30-60 minutes as required. Do not take more than 8 doses in 24 hours.
For children under the age of 16
Not recommended for use in this age group.
Pepto Bismol can be taken with or without food. Only take this medication for a maximum of 2 days - if your symptoms are not improving, you should contact your GP.
For the liquid formulation, shake the bottle before use and use the measuring cup provided with the medication to measure out your dose.
For the tablet formulation, you should chew the tablets or let them dissolve on your tongue.
If you are taking this medication to treat symptoms of diarrhoea, you should drink plenty of water to avoid dehydration.
If you take too much Pepto Bismol, you should contact NHS 111, who will advise you on what to do next.
Pepto Bismol can cause some side effects; however, not everyone will get them.
The most common side effects are:
- Black or grey coloured stools
- Black or darkened tongue
- Constipation
In rare cases, patients may experience internal bleeding.
Symptoms of internal bleeding are:
- Bloody or tar-like stools
- Vomit that looks like coffee grounds
- Severe abdominal pain that doesn’t go away
In rare cases, patients may experience an allergic reaction.
Symptoms of a severe allergic reaction are:
- Hives
- An itchy rash
- Swelling of the face, lips, throat, or tongue
- Difficulty breathing
If you are concerned that you’re experiencing internal bleeding or an allergic reaction, stop taking Pepto-Bismol and seek medical attention immediately.
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Our Clinical Authors
This page has been written by a registered UK pharmacist and reviewed by our clinical team to ensure it is accurate, clear and reflects current clinical guidance.
Last medically reviewed: 06 July 2026
Last updated: 06 July 2026