Can propranolol (beta blocker) cause constipation?

Propranolol and Constipation

Propranolol can cause constipation as a gastrointestinal side effect, as documented in the FDA drug label. 1

Mechanism of Action

• Propranolol is a non-selective beta-blocker that can affect gastrointestinal motility by blocking beta-adrenergic receptors in the gastrointestinal tract 1, 2
• Studies show that beta-blockers like propranolol can enhance colonic motility, which paradoxically may lead to constipation in some patients due to altered bowel function 2
• The effect appears to be dose-dependent, with higher doses more likely to cause gastrointestinal side effects 1

Evidence from Drug Labeling and Guidelines

• The FDA drug label for propranolol specifically lists constipation as a potential gastrointestinal adverse effect 1
• The European Society of Cardiology guidelines identify constipation as one of the potential adverse effects of beta-blockers, including propranolol 3
• Verapamil (a calcium channel blocker) is specifically mentioned as problematic for constipation in people ≥75 years, but beta-blockers like propranolol are also noted to have gastrointestinal effects 3

Clinical Studies on Beta-Blockers and Bowel Function

• Research has demonstrated that both non-selective (propranolol) and beta-1 selective (metoprolol) beta-blockers can enhance distal colonic pressure in humans 2
• A study in patients with irritable bowel syndrome showed that propranolol administration was followed by an increase in colonic motility in 9 out of 10 patients, which may explain abdominal symptoms and changes in bowel habits 4
• While some patients experience constipation, others may experience diarrhea with propranolol, as reported in a case study of a 71-year-old female who developed severe diarrhea at a dose of 20 mg four times daily 5

Management of Propranolol-Induced Constipation

• For patients who develop constipation while taking propranolol, consider the following management options:

  • Osmotic laxatives such as polyethylene glycol (PEG) or magnesium-based products may be used 3
  • Stimulant laxatives such as bisacodyl or senna can be added if osmotic laxatives are insufficient 3
  • Adequate fluid intake and physical activity should be encouraged when appropriate 3

• If constipation persists despite laxative therapy:

  • Consider dose reduction of propranolol if the therapeutic effect can be maintained 3
  • Evaluate for switching to a different beta-blocker with potentially fewer gastrointestinal effects 3
  • Rule out other causes of constipation such as opioid use, hypercalcemia, or bowel obstruction 3

Clinical Considerations and Monitoring

• Patients starting propranolol should be informed about the potential for constipation as a side effect 1
• Elderly patients may be more susceptible to developing constipation due to reduced gastrointestinal motility and other age-related factors 3
• Regular monitoring of bowel habits is recommended in patients taking propranolol, especially those with pre-existing gastrointestinal conditions 3

Conclusion

• While constipation is a documented side effect of propranolol in the FDA drug label, the clinical presentation can vary, with some patients experiencing increased colonic motility or even diarrhea 1, 4, 5
• The gastrointestinal effects appear to be related to the drug's impact on beta-adrenergic receptors in the gastrointestinal tract 2
• Management should focus on appropriate laxative therapy and consideration of dose adjustment or medication change if constipation becomes problematic 3