Anti-diarrheal Medicines: OTC Relief for Diarrhea

Diarrhea is when you have frequent and liquid bowel movements. Many things can cause it, including:

  • Viruses.
  • Bacteria and parasites.
  • Medicines such as antibiotics.
  • Lactose intolerance.
  • Fructose or artificial sweeteners.
  • Digestive disorders such as celiac disease or irritable bowel syndrome.

It is a common condition that most of the time doesn’t require treatment. It usually lasts only a couple of days, whether you treat it or not. But medicine can help you feel better. It especially helps if you also have cramping or stomach pain.

What types of OTC medicines treat diarrhea?

You can buy over-the-counter (OTC) medicines without a prescription from your doctor. Some OTC medicines can help you feel better if you have diarrhea. These are called antidiarrheal medicines. Antidiarrheal medicines include:

  • Loperamide (1 brand name: Imodium).
  • Bismuth subsalicylate (2 brand names: Kaopectate, Pepto-Bismol).

Bismuth subsalicylate can also be used for an upset stomach.

Path to Improved Wellness

How do OTC antidiarrheal medicines work?

Loperamide slows down how fast things move through your intestines (bowels). This allows more fluid to be absorbed into your body. This helps you have less diarrhea and more formed stools.

Bismuth subsalicylate balances the way fluid moves through your intestines. It reduces inflammation. It keeps bacteria and viruses that cause diarrhea from growing in the stomach and intestines.

How do I safely take OTC antidiarrheal medicines?

Before you take an OTC antidiarrheal medicine, read the directions on the drug facts label. This will tell you how much medicine to take and how often to take it. If you have any questions, call your family doctor or pharmacist. Keep a record of which OTC medicines you are using and when you take them. If you need to go to the doctor, take this list with you.

Follow these tips to make sure you are taking the right amount of medicine:

  • Take only the amount recommended on the medicine’s label. Don’t assume that more medicine will work better or quicker. Taking more than the recommended amount can be dangerous.
  • If you take prescription medicine, ask your doctor if it’s okay to take OTC antidiarrheal medicine.
  • Don’t use more than one OTC antidiarrheal medicine at a time unless your doctor says it’s okay. They may have similar active ingredients. These could add up to be too much medicine.

How can I safely store OTC antidiarrheal medicines?

Store all medicines up and away, out of reach and sight of young children. Keep medicines in a cool, dry place. This will help prevent them from becoming less effective. Do not store medicines in bathrooms or bathroom cabinets. They are often hot and humid.

Things to Consider

Healthy adults usually don’t experience side effects from antidiarrheal medicines. But side effects may be a concern if you are older or have health problems. Call your doctor if you notice any side effects.

Loperamide side effects may include:

  • Abdominal pain.
  • Constipation.
  • Dizziness.
  • Nausea or vomiting.

Bismuth subsalicylate side effects may include:

  • Constipation.
  • Blackened stools and/or tongue.
  • Ringing sound in the ear (called tinnitus).

Who shouldn’t take OTC antidiarrheal medicines?

Don’t take antidiarrheal medicines if bacteria or parasites are causing your diarrhea. If you have a “stomach bug,” your body needs to get rid of the bacteria or parasite that is causing the diarrhea. Stopping the diarrhea in this case can actually make your condition worse. Talk to your family doctor if you think you have a bacterial or parasitic infection.

Don’t give loperamide to children 2 years of age or younger unless your doctor says it’s okay. Check with your doctor before using loperamide for older children, as well.

You shouldn’t take loperamide if you have a fever. Don’t use it if you’ve ever had a rash or an allergic reaction after taking it. Don’t take loperamide if you have bloody or black stools. These may be signs of a more serious problem, such as a bacterial infection.

Some people are allergic to aspirin or other salicylate medicines. They should not take bismuth subsalicylate. Don’t give bismuth subsalicylate to children 12 years of age or younger. Don’t give it to children or teenagers who may have the flu or chickenpox. This increases their risk for Reye syndrome. This is a serious illness that can lead to death.

Can OTC antidiarrheal medicines cause problems with other medicines I take?

Taking certain medicines with antidiarrheal medicines can increase your risk for side effects. Bismuth subsalicylate also may affect some medicines, causing them not to work as well. Ask your doctor before taking loperamide or bismuth subsalicylate if you also take:

  • Antibiotics.
  • Antiviral medicines for human immunodeficiency virus (HIV).
  • Prescription pain medicines.
  • Blood-thinning medicines.
  • Medicines for gout.
  • Medicines for arthritis.
  • Medicines for diabetes.

Also ask your doctor before taking bismuth subsalicylate if you take pain relievers or cold medicines. These medicines may contain aspirin, which is a salicylate. You may get too much salicylate if you take more than one of these medicines at a time.

When should I call my doctor?

Talk to your doctor before taking an antidiarrheal medicine if:

  • Your diarrhea lasts longer than 2 days.
  • You have a fever.
  • You have mucus or blood in your stools.
  • You have a history of liver disease.
  • You are taking prescription medicine.

Questions to Ask Your Doctor

  • What is causing my diarrhea?
  • How long will it last if I don’t treat it?
  • Will taking an OTC antidiarrheal medicine shorten the length of time the diarrhea lasts?
  • What can I be doing to treat my diarrhea in addition to taking OTC medicines?
  • Will antidiarrheal medicines make me constipated?
  • What side effects should I watch out for if I take antidiarrheal medicine?


International Foundation for Gastrointestinal Disorders: Antidiarrheal Agents