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Pepto-Bismol - (bismuth subsalicylate)

On this page

  1. About Pepto-Bismol
  2. Key facts
  3. Who can and can't take Pepto-Bismol
  4. How and when to take it
  5. Side effects
  6. Pregnancy and breastfeeding
  7. Cautions with other medicines
  8. Common questions

1. 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.

2. 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.

3. 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.

4. 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.

Urgent advice: Speak to a doctor or pharmacist now if:

  • you take too much Pepto-Bismol

5. 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.

Immediate action required: Call 999 or go to A&E 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.


You can report any suspected side effect to the UK safety scheme.

6. 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.

Non-urgent advice: Tell your doctor if you're:

  • pregnant
  • trying to get pregnant
  • breastfeeding

7. 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.

8. Common questions

How does Pepto-Bismol work?

We do not fully understand how Pepto-Bismol works.

The medicine forms a protective coating over the lower part of your food pipe (oesophagus), and partly coats your stomach. This helps protect them from stomach acid.

It also has weak antacid properties that may help reduce excess stomach acid. This will ease feelings of pain and discomfort.

How long does it take to work?

Pepto-Bismol should work within 30 to 60 minutes.

You can have another dose after 30 to 60 minutes, if you need to.

You can take up to 8 doses in 24 hours.

How long will I take it for?

You can take Pepto-Bismol for up to 2 days.

Do not take Pepto-Bismol for more than 2 days as this will increase your risk of getting side effects.

If your symptoms are no better or are getting worse after 2 days, contact your doctor. However if your symptoms are serious, it's important to speak to a doctor right away.

Urgent advice: Contact a doctor now if you have:

  • diarrhoea and a high temperature or severe stomach pain
  • blood or mucus in your poo
Are there other indigestion medicines?

There are a number of different medicines for indigestion and heartburn.

  • Antacids include Tums (calcium carbonate), Maalox and Milk of Magnesia. These relieve indigestion and heartburn by neutralising the acid in your stomach. They work quickly and make you feel better for a few hours. They're ideal if you occasionally get stomach acid problems. You can get antacids from pharmacies and supermarkets.
  • Proton pump inhibitors (PPIs) reduce the amount of acid your stomach produces. Most PPIs are available on prescription only - they include omeprazole and lansoprazole. You can buy the lowest-strength omeprazole and esomeprazole from pharmacies.
  • H2 blockers (histamine antagonists) reduce the amount of acid made in your stomach, but they do this in a different way to PPIs. For example, your doctor might prescribe ranitidine (Zantac), cimetidine (Tagamet), famotidine (Pepcid) and nizatidine (Axid). You can also buy famotidine and ranitidine from pharmacies.
Can I take Pepto-Bismol with other indigestion medicines?

If Pepto-Bismol is not helping with your symptoms, speak to your doctor or a pharmacist. They will be able to recommend an alternative.

Do not combine different medicines for indigestion without asking for expert advice.

Will it affect my fertility?

There's no firm evidence to suggest that taking Pepto-Bismol will reduce fertility in either men or women.

Will it affect my contraception?

Pepto-Bismol does not affect any type of regular contraception including the contraceptive pill and emergency contraception.

However, if you are on the pill and have diarrhoea for more than 24 hours, you may need to use extra contraception. Find out what to do if you are on the pill and have sickness or diarrhoea.

Can I drive or ride a bike?

Taking Pepto-Bismol will not usually affect your ability to drive a car or ride a bike.

However, taking too much Pepto-Bismol can make you feel confused, tired or dizzy. It can also affect your hearing or cause ringing or buzzing in your ears. If you have any of these symptoms, do not drive or ride a bike until you feel OK again.

Can I drink alcohol with it?

Alcohol does not interfere with the way Pepto-Bismol works. However, drinking alcohol makes your stomach produce more acid than normal. This can irritate your stomach lining and make your symptoms worse.

If you have diarrhoea, drinking alcohol may make you more dehydrated. It's best to avoid alcohol until your symptoms are better.

Can lifestyle changes help?

Making a few changes to your diet and lifestyle may help if you have problems caused by too much stomach acid.

It can help if you:

  • keep to a healthy weight or lose weight if you need to - extra weight can put pressure on your stomach and make acid reflux worse
  • do not eat foods that can make your symptoms worse, including rich, spicy and fatty foods, and acidic foods like tomatoes, citrus fruits, salad dressings and fizzy drinks
  • cut down on caffeinated drinks, such as tea, coffee and cola, as well as alcohol and smoking
  • try not to eat for at least 3 hours before you go to bed
  • raise the head of your bed a little, so that your head is higher than your stomach
  • quit smoking - you can call the NHS Stop Smoking Helpline on 0300 123 1044

Page last reviewed: 13 August 2019
Next review due: 13 August 2022