About Pepto-Bismol

Bismuth subsalicylate is the main ingredient in Pepto-Bismol. This medicine is used for heartburn and acid reflux, indigestion, diarrhoea and feeling sick (nausea).

It works by protecting your stomach and the lower part of your food pipe from stomach acid. It is also a mild antacid, which helps reduce excess stomach acid and eases any discomfort.

Pepto-Bismol comes as tablets and a liquid that you drink. You can only buy it from pharmacies.

Key facts

  • Pepto-Bismol can be taken by adults over the age of 16 years.
  • You can take it with or without food.
  • Speak to a doctor if your symptoms are not any better after 2 days.
  • If you're allergic to aspirin (or any of the ingredients in Pepto-Bismol) check with a pharmacist before taking this medicine.
  • This medicine is also sold under the brand name Pepti-Calm.

Who can and can't take Pepto-Bismol

Pepto-Bismol can be taken by most adults and young people from the age of 16 years.

Do not take this medicine if you are pregnant or breastfeeding.

Pepto-Bismol is not suitable for some people. To make sure this medicine is safe for you, tell your doctor or pharmacist if you have:

  • had an allergic reaction to Pepto-Bismol, aspirin or any other medicines in the past
  • an allergy to amaranth or aspartame
  • a problem with blood clotting
  • diabetes
  • gout
  • a rare inherited illness called phenylketonuria - the chewable tablets contain aspartame

Pepto-Bismol liquid and tablets both contain a colouring called amaranth. Some people can have an allergic reaction to amaranth.

How and when to take it

Only take Pepto-Bismol when you need it. You can take it for occasional heartburn, indigestion or an upset stomach.


Do not take Pepto-Bismol for more than 2 days.

If your symptoms have not improved within 2 days, speak to your doctor.

How much to take

Liquid: a single dose is 30ml. Use the measuring cup that comes with the medicine to make sure you get the right amount.

Tablets: a single dose is 2 tablets. Chew the tablets or let them dissolve on your tongue.

If you need to, repeat this dose every 30 to 60 minutes. Do not take more than 8 doses in 24 hours.

How to take it

You take Pepto-Bismol with or without food.

If you're taking Pepto-Bismol for diarrhoea, make sure you drink plenty of fluids to avoid dehydration.

What if I take too much?

Taking too much Pepto-Bismol can increase the risk of side effects.

Side effects may include feeling or being sick, feeling confused, dizzy or tired, deafness, or ringing or buzzing in your ears.

Speak to a doctor or pharmacist now if:

  • you take too much Pepto-Bismol

Side effects

You're unlikely to get any side effects from Pepto-Bismol if you follow the instructions for taking it.

One common side effect is your poo or your tongue turning black. This is harmless.

This happens when bismuth (the active ingredient in this medicine) comes into contact with small amounts of sulphur in your saliva and digestive system. They combine to form bismuth sulfide, a black substance. This side effect usually goes away when you stop taking the medicine.

If your tongue or your poo is still black after 3 days, or after you've stopped taking Pepto-Bismol, speak to your doctor or a pharmacist.

Tell your doctor or a pharmacist if you have any other side effects that bother you or do not go away.

Serious allergic reaction

In rare cases, it's possible to have a serious allergic reaction (anaphylaxis) to Pepto-Bismol.

Call your local emergency service if:

  • you get a skin rash that may include itchy, red, swollen, blistered or peeling skin
  • you're wheezing
  • you get tightness in the chest or throat
  • you have trouble breathing or talking
  • your mouth, face, lips, tongue or throat start swelling

You could be having a serious allergic reaction and may need immediate treatment in hospital.

These are not all the side effects of Pepto-Bismol. For a full list see the leaflet inside your medicines packet.

Pregnancy and breastfeeding

Do not take Pepto-Bismol if you're pregnant or breastfeeding.

It's best to try to treat your indigestion without taking a medicine. It can help to:

  • eat smaller meals and more often
  • avoid fatty or spicy foods, and avoid alcohol and cigarettes
  • raise one end of your bed a little, so your head is higher than your stomach
  • avoid lying down immediately after eating
  • drink water between meals rather than with meals

If this advice does not work, speak to your doctor or a pharmacist. They will be able to recommend the most suitable medicine for you and your baby.

Tell your doctor if you're:

  • pregnant
  • trying to get pregnant
  • breastfeeding

Cautions with other medicines

Pepto-Bismol contains salicylates (also found in aspirin) and can interfere with certain other medicines.

To make sure Pepto-Bismol is safe for you, tell your doctor or a pharmacist if you are taking:

  • blood thinners (anticoagulants)
  • tablets or other oral medicines for diabetes
  • medicine for gout
  • doxycyline or minocycline, or any other tetracycline antibiotics

If you're taking tetracycline antibiotics, you need to leave a 2-hour gap before taking Pepto-Bismol.

It's safe to take paracetamol at the same time as Pepto-Bismol. Do not take other painkillers, like ibuprofen or aspirin, with Pepto-Bismol without talking to your doctor or pharmacist first. This could make your symptoms worse.

Mixing Pepto-Bismol with herbal remedies and supplements

There's very little information about taking herbal remedies and supplements with Pepto-Bismol.


For safety, tell your doctor or pharmacist if you're taking any other medicines, including herbal remedies, vitamins or supplements.

Common questions