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Loperamide: 7 things you should know

Medically reviewed by Carmen Fookes, BPharm. Last updated on Dec 29, 2019.

1. How it works

  • Loperamide is used to treat diarrhea or loose stools.
  • Loperamide works on mu opioid receptors in the gut wall to slow down the movement of the gut. This slows the contractions of the intestine, allowing more water to be absorbed back into the body through the intestinal wall, making the stool less watery and decreasing the number of bowel movements. Loperamide does not affect the brain and central nervous system. Loperamide also suppresses the gastrocolic reflex and may directly inhibit fluid and electrolyte secretion or stimulate salt and water absorption.
  • Loperamide belongs to the class of medicines known as antidiarrheals.

2. Upsides

  • Loperamide is used to treat diarrhea.
  • Loperamide may also be used in people who have had an ileostomy (a surgical operation where part of the bowel is removed and the cut end diverted to the surface of the abdomen) to reduce the amount of bowel discharge.
  • Loperamide decreases the number of bowel movements and makes the stool less watery.
  • Loperamide is long-acting.
  • Tolerance to the antidiarrheal effect of loperamide has not been observed.
  • Unlikely to cause drowsiness.
  • Loperamide is available as a generic.

3. Downsides

If you are between the ages of 18 and 60, take no other medication or have no other medical conditions, side effects you are more likely to experience include:

  • Constipation (this may be a sign that too much loperamide has been taken).
  • Rarely may cause dizziness or drowsiness which may affect your ability to drive or operate machinery. Avoid alcohol.
  • Bloating, loss of appetite, stomach pain, and skin rash are also rare side effects of loperamide.
  • May not be suitable for people with a bowel obstruction, abdominal pain without diarrhea, blood or mucus in their diarrhea, or phenylketonuria (some loperamide tablets contain aspartame or phenylalanine).
  • May interact with antibiotics or some medications used to treat HIV.
  • Not to be used in children aged less than six years except on a doctor's advice. Children may be more sensitive to the effects of loperamide.
  • Not to be used during pregnancy or breastfeeding except on a doctor's advice.

Notes: In general, seniors or children, people with certain medical conditions (such as liver or kidney problems, heart disease, diabetes, seizures) or people who take other medications are more at risk of developing a wider range of side effects. For a complete list of all side effects, click here.

4. Bottom Line

  • Loperamide effectively treats diarrhea by slowing down the movement of the bowel. In some people it may cause drowsiness.

5. Tips

  • May be taken with or without food.
  • If you have brought loperamide over the counter, follow the dosing instructions on the packet. Use weight in preference to age if known. Take only as directed. Do not take more than recommended.
  • Drink extra fluids such as electrolyte solutions to maintain good hydration. Electrolyte solutions replace electrolytes that are typically lost during diarrhea.
  • Avoid becoming overheated or dehydrated while taking loperamide.
  • Do not drive or operate machinery if loperamide makes you drowsy or dizzy. Avoid alcohol.
  • See your doctor if your diarrhea does not get better within 48 hours or gets worse, or if you develop a distended, bulging, or painful stomach.
  • Stop taking loperamide and seek immediate medical attention if a rash, itching, facial swelling, difficulty breathing, bloating, blood in your stools, or severe dizziness develop.

6. Response and Effectiveness

  • Some of loperamide's effects may be apparent within 20 minutes. However, it takes about 2.5 hours (oral solution) or 5 hours (capsules) for loperamide to reach its peak effect.

7. Interactions

Medicines that interact with loperamide may either decrease its effect, affect how long it works for, increase side effects, or have less of an effect when taken with loperamide. An interaction between two medications does not always mean that you must stop taking one of the medications; however, sometimes it does. Speak to your doctor about how drug interactions should be managed.

Common medications that may interact with loperamide include:

  • lumacaftor and other P-glycoprotein/ABCB1 substrates
  • sincalide
  • other medications that have the potential to prolong the QT-interval, such as haloperidol, quinidine, or amiodarone
  • other medications that cause constipation, such as ondansetron, opioids, or ramosetron.

Note that this list is not all-inclusive and includes only common medications that may interact with loperamide. You should refer to the prescribing information for loperamide for a complete list of interactions.


Loperamide [Package Insert] Revised 10/2019.

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use loperamide only for the indication prescribed.

Copyright 1996-2020 Revision date: December 28, 2019.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.