Antidiarrheal Medicines: OTC Relief for Diarrhea

Over-the-counter (OTC) drugs are medicines you can buy without a prescription from your doctor. Some OTC drugs can help you feel better if you have diarrhea. These are called antidiarrheal drugs. These include loperamide (one brand name: Imodium) and bismuth subsalicylate (brand names: Kaopectate, Pepto-Bismol). Bismuth subsalicylate can also be used for upset stomach and as an antiemetic (a medicine that treats nausea and vomiting).

Depending on the cause of your diarrhea, you may also need to take antibiotics prescribed by your doctor. Antibiotics are medicines that kill bacteria. For example, traveler’s diarrhea (diarrhea caused by eating food and drinking water that contain germs) may require antibiotics. If your doctor prescribes an antibiotic for you, it’s important to talk to your doctor before taking any OTC medicine to relieve your symptoms.

Loperamide works by slowing down the speed of fluids moving through your bowels.

Bismuth subsalicylate works by balancing the way fluid moves through your bowels. It also binds toxins (poisons) from bacteria so that they are not harmful and helps kill germs.

Most of the time, diarrhea doesn’t require treatment. It most often lasts only a couple of days whether you treat it or not. However, medicine can help you feel better, especially if you also have cramping.

Side effects from antidiarrheal drugs aren’t common for healthy adults. Side effects may be a concern for older adults or people who have health problems. If side effects occur with antidiarrheal medicines, they’re usually very minor. For example, too much loperamide can lead to constipation. Sometimes people who use loperamide have crampy pain. Bismuth subsalicylate can cause your tongue or stool to turn dark. This is a short-term side effect.

Don’t take loperamide if you’ve ever had a rash or other signs of an allergic reaction when taking it. Also, don’t use loperamide if you have bloody or black stools. These may be signs of a more serious problem, so talk to your doctor.

Don’t take bismuth subsalicylate if you’ve ever had an allergy to aspirin or any other product that contains salicylates. Also, don’t give bismuth subsalicylate to children who may have the flu or chickenpox because they will have a higher risk of Reye’s Syndrome.

If certain drugs are taken at the same time, they may interact with each other and change the way your body processes them. This is called a drug interaction. When this happens, the risk of side effects increases.

Bismuth subsalicylate may affect some drugs so that they don’t work as well. It also may cause side effects if combined with other drugs. If you take any of the following drugs, talk to your doctor before taking bismuth subsalicylate:

Also, check with your doctor before taking bismuth subsalicylate if you take pain relievers, cold products or some prescription drugs. These medicines may contain aspirin, which is a salicylate, or they may contain some other type of salicylate. Because bismuth subsalicylate also contains salicylate, you may take more salicylate than you intend if you take more than one of these products.

The Know What’s in the Medicines You Take chart (PDF file: 6 pages / 75 KB. More about PDFs.) can help sort out which drugs contain aspirin so you can avoid taking too much.

If you have a fever, mucus or blood in your stools, or a history of liver disease, talk to your doctor before taking an antidiarrheal.

Also, if your diarrhea goes on for more than 2 days, call your doctor. Don’t keep trying to treat it on your own. Diarrhea that goes on for more than 2 days may be caused by something more than a short-term “bug.” You may need an antibiotic prescribed by your doctor to help clear it up or it may be a sign of another problem that needs to be checked.

When choosing an OTC medicine to treat diarrhea, check the drug label for possible side effects or interactions with other drugs you’re taking. This information will appear in the “Warnings” section of the label.

Be sure to check that you’re not taking two medicines that contain the same ingredient. You’ll find this information in the “Active Ingredient” section.

Always read and follow the directions on the label. Be sure you understand what the label says before taking the medicine. If you have any questions, ask your family doctor or pharmacist.