From the Research
To prevent constipation when using antipsychotics, the first-line recommendation is to increase dietary fiber intake to 25-30 grams daily, ensure adequate hydration with at least 2 liters of water per day, and maintain regular physical activity. Antipsychotic medications, particularly clozapine, olanzapine, and quetiapine, commonly cause constipation by slowing intestinal motility through anticholinergic effects 1. If lifestyle modifications are insufficient, consider adding an osmotic laxative such as polyethylene glycol (MiraLAX) 17 grams mixed in 8 ounces of water daily. Stimulant laxatives like bisacodyl or senna should be reserved for short-term use if osmotic agents fail. Prophylactic laxative therapy may be warranted for patients on high-risk antipsychotics or those with additional risk factors such as older age, multiple anticholinergic medications, or history of constipation 2. Some key points to consider when managing antipsychotic-induced constipation include:
- Regular monitoring of bowel movements is important, and intervention should occur if a patient hasn't had a bowel movement for 2-3 days.
- Addressing constipation proactively helps improve medication adherence and prevents more serious complications like bowel obstruction.
- The mechanisms of antipsychotic-induced constipation may be antagonism of cholinergic, histaminergic, and serotonergic receptors, with both parent drug and metabolite(s) contributing to the effects on gastrointestinal motility 3.
- Limited fluid intake, poor dietary habits, and a sedentary lifestyle can also worsen constipation.
- Antipsychotic drug-induced constipation should be closely monitored in patients receiving these medications, with timely intervention to avoid serious gastrointestinal consequences 3. The most recent and highest quality study available is from 2025, which analyzed the potential risk of antipsychotics-related constipation from the FDA Adverse Event Reporting System, and found that clozapine, olanzapine, amsulpride, quetiapine, and paliperidone were correlated with constipation, while risperidone had the least effect on gastrointestinal function 1.