Drug Safety Alert: Loperamide

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Loperamide is a weak opioid agonist and works by slowing the movement of intestines. It is an over-the-counter (OTC) medication used to control the symptoms of diarrhea, including Travelers’ diarrhea. The maximum daily dose for adults is 8mg for OTC use, while 16mg for prescription use. It is relatively safe with low gastrointestinal absorption and poor blood-brain barrier penetration in normal doses. 

Multiple cases of cardiovascular toxicity (e.g. arrhythmias, arrest) and death have been reported with misuse and abuse of loperamide. Patients who have intentionally overdosed themselves are attempting to self-medicate opioid withdrawal symptoms or to achieve euphoric effects. Some patients take medications that increases the absorption and levels of loperamide in the body. Healthcare workers should also be aware of other medications which may potentially interact with loperamide (refer to table 1). These drugs may increase the absorption of loperamide or may enhance its arrhythmogenic effect. 

Drugs that may interact with Loperamide:

  • Cimetidine 
  • Clarithromycin 
  • Erythromycin 
  • Gemfibrozil 
  • Itraconazole 
  • Ketoconazole 
  • Quinidine 
  • Quinine 
  • Ranitidine 
  • Ritonavir 

It is prudent to advise patients in adhering with the prescribed and approved dosage. Pharmacists should be able to monitor and advise patients properly if patients are unsure of how much dose to take. Screening for possible drug interactions must be done to reduce the risk of adverse heart problems with loperamide. Advise patients to seek medical attention if he/she experiences fainting or rapid heartbeat. 



  1. https://www.fda.gov/downloads/Drugs/DrugSafety/UCM505108.pdf 
  2. https://www.fda.gov/Safety/MedWatch/SafetyInformation/SafetyAlertsforHumanMedicalProducts/ucm594403.htm 

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