Loperamide
Say it: loh-PAIR-uh-mide · Brand names: Imodium
Loperamide is a medicine that helps slow down and stop diarrhea.
What it is
Diarrhea happens when food and water move through your gut too fast. Loperamide slows the muscles of the gut. This gives your body more time to soak up water, so stools become firmer and less frequent.
Often used for
- diarrhea, including diarrhea from cancer treatment
- long-term diarrhea from bowel diseases
- lowering stool output in people with an ileostomy
How you get it
It is a pill, capsule, or liquid taken by mouth. You can buy it without a prescription, but your cancer team may give you a special plan for how often to take it. Follow your team's plan, even if it is different from the box. Your schedule may be different.
Common side effects and what helps
- Constipation. Tell your team, since you may need to stop or take less.
- Belly cramps or bloating. Tell your team if it is strong.
- Feeling dizzy or sleepy. Stand up slowly and do not drive if you feel sleepy.
- Nausea. Sip fluids slowly.
- Dry mouth. Sip water often.
Call your care team right away if you have
- Diarrhea that does not get better, or 4 or more extra stools a day compared with your normal, even with this medicine
- Blood in your stool, or black stools
- A fever of 100.4 degrees Fahrenheit (38 degrees Celsius) or higher
- Signs of dehydration, like feeling very dizzy, very thirsty, or peeing very little
- A swollen, hard, or painful belly
- A fast or uneven heartbeat, or fainting
Before you start, tell your team
- What cancer medicines you take. Some cause diarrhea that needs a special plan.
- If you have a fever or blood in your stool
- If you have liver problems or a heart rhythm problem
- All medicines you take, since some can raise loperamide levels
- If you are pregnant or breastfeeding
Good to know
- Taking more than your team or the label says can cause serious heart rhythm problems.
- Do not use it for diarrhea with fever or bloody stools unless your team says to. It can make some infections worse.
- Drink plenty of fluids while you have diarrhea to replace what you lose.
- Do not give it to children under 2 years old.
At home
- Follow the diarrhea plan your cancer team gave you. It may be different from the box.
- Keep it at home so you can start it as soon as diarrhea begins, if your team tells you to.
- Drink plenty of clear fluids.
- If you are not sure how much to take, ask your team.
- Store at room temperature, away from children.
Questions to ask
- When should I start this medicine?
- How much can I take in one day?
- When should I call you about diarrhea?
Side effect guides
Sources
Quick answers
- What is Loperamide?
- Loperamide is a medicine that helps slow down and stop diarrhea. Brand names: Imodium.
- What is Loperamide used for?
- diarrhea, including diarrhea from cancer treatment; long-term diarrhea from bowel diseases; lowering stool output in people with an ileostomy.
- How is Loperamide given?
- It is a pill, capsule, or liquid taken by mouth. You can buy it without a prescription, but your cancer team may give you a special plan for how often to take it. Follow your team's plan, even if it is different from the box. Your schedule may be different.
- What are the common side effects of Loperamide?
- Constipation. Belly cramps or bloating. Feeling dizzy or sleepy. Nausea. Dry mouth.
- When should I call my care team while taking Loperamide?
- Diarrhea that does not get better, or 4 or more extra stools a day compared with your normal, even with this medicine; Blood in your stool, or black stools; A fever of 100.4 degrees Fahrenheit (38 degrees Celsius) or higher; Signs of dehydration, like feeling very dizzy, very thirsty, or peeing very little; A swollen, hard, or painful belly; A fast or uneven heartbeat, or fainting.
Last updated: 2026-10-27. Medically reviewed by Veli Bakalov, MD, medical oncologist (October 2026). General education from Step by Step, the patient portal of HemeOncBuddy.