How do antidiarrheal medicines work?

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

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

Should I treat diarrhea?

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.

When diarrhea is a symptom of an infection caused by bacteria or parasites, antidiarrheal medicines can actually make the condition worse. This is because the medicine keeps your body from getting rid of the bacteria or parasite that is causing the diarrhea. Talk to your family doctor if you have any reason to think your diarrhea might be caused by a bacterial or parasitic infection.

Depending on the cause of your diarrhea, you may also need to take antibiotics prescribed by your doctor. Antibiotics are medicines that kill bacteria. 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.

Who shouldn't take these medicines?

Don’t give loperamide to children 6 years of age or younger unless your doctor says it’s okay. You shouldn’t take loperamide if you have a fever, or 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, including a bacterial infection, so talk to your family doctor.

People who are allergic to aspirin or other salicylate medicines should not take bismuth subsalicylate. Don’t give bismuth subsalicylate to children 12 years of age or younger. Don’t give bismuth subsalicylate to children or teenagers 12 to 18 years of age who may have the flu or chickenpox. This increases their risk for Reye’s syndrome, which is a serious illness that can lead to death.

What are some common side effects of antidiarrheal drugs?

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

• Loperamide side effects:
  • Abdominal pain
  • Constipation
  • Dizziness
  • Nausea or vomiting
    
• Bismuth subsalicylate side effects:
  • Constipation
  • Blackened stools and/or tongue
  • Ringing sound in the ear (called tinnitus)

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

Using any of the following medicines with loperamide can increase your risk for side effects, so your doctor may need to adjust your dosages. Ask your doctor before taking loperamide if you also take:

• Antibiotics
• Antiviral medicines for human immunodeficiency virus (HIV)
• Prescription pain medicines

Bismuth subsalicylate may cause side effects if combined with other medicines. Ask your doctor before taking bismuth subsalicylate if you also take:

• Blood-thinning medicines
• Medicines for gout
• Medicines for arthritis
• Medicines for diabetes

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

When should I call my doctor?

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

Funding and support for this material have been provided by the Consumer Healthcare Products Association.