From the Guidelines
Loperamide can cause several side effects, including constipation, dizziness, drowsiness, and nausea, and its use should be approached with caution, especially in certain populations, as indicated by recent guidelines 1.
Common Side Effects
- Constipation
- Dizziness
- Drowsiness
- Nausea Some people may experience abdominal pain, bloating, dry mouth, or vomiting.
Serious Side Effects
More serious but less common side effects include severe constipation, stomach pain with bloating, allergic reactions (rash, itching, swelling), and in rare cases, toxic megacolon (a dangerous enlargement of the colon). At high doses, particularly when misused, loperamide can cause serious heart problems including abnormal heart rhythms and cardiac arrest, as noted in studies on its safety profile 1. It may also cause central nervous system depression with symptoms like confusion or unresponsiveness when taken in excessive amounts. People with inflammatory bowel conditions, liver disease, or those taking certain medications should use loperamide cautiously, as advised by clinical practice guidelines 1. The drug works by slowing intestinal movement and reducing the frequency of bowel movements by binding to opioid receptors in the intestinal wall, though at recommended doses it doesn't typically enter the bloodstream or cause opioid effects in the brain, as explained in pharmacological studies 1.
Special Considerations
Loperamide should not be given to children <18 years of age with acute diarrhea, and its use in adults should be considered once the patient is adequately hydrated, as recommended by infectious diseases guidelines 1. Its efficacy and safety have been supported by various studies, including those comparing it to other treatments for travelers' diarrhea 1, and guidelines for adults on self-medication for acute diarrhea 1. However, the most recent and highest quality evidence should always guide clinical decision-making, prioritizing patient safety and outcomes 1.
From the FDA Drug Label
Side effects: Constipation, after prolonged treatment. The side effects of Loperamide include constipation, particularly after prolonged treatment 2.
- Common side effect: Constipation The main side effect to be concerned about is constipation, especially with long-term use.
From the Research
Loperamide Side Effects
- The most common side effects of loperamide are related to its impact on bowel motility, including:
- Abdominal pain
- Distention
- Bloating
- Nausea
- Vomiting
- Constipation 3
- High dosage of loperamide can induce an opioid-like effect on the central nervous system, leading to serious cardiac dysrhythmia and potentially death 4
- Loperamide overdose can result in serious adverse effects, including syncope caused by cardiac dysrhythmia 4
- Common side effects of loperamide in the treatment of acute diarrhea include constipation, with 8 out of 219 subjects experiencing constipation in one study 5
- No significant differences in adverse events were found among treatment groups in a study comparing loperamide-simethicone with loperamide, simethicone, or placebo alone 6
Less Common Side Effects
- Loperamide has been observed to increase anal sphincter tone, which may lead to improvement of fecal continence in patients with and without diarrhea, but can also lead to constipation 3
- Loperamide is generally well tolerated at recommended nonprescription doses, but high doses can lead to more severe side effects 3, 4