Medications that can cause constipation: Analgesic drugs: nonsteroidal anti-inflammatory drugs, opioids (25% to 40% in noncancer patients and ≤90% in cancer patients) Anticholinergic drugs: antipsychotic drugs, benztropine, oxybutynin Anti-Parkinson drugs: amantadine, bromocriptine, pramipexole Anticonvulsant drugs: gabapentin, phenytoin, pregabalin Antidepressant drugs: tricyclic antidepressants, paroxetine Antidiarrheal drugs: diphenoxylate, loperamide Antiemetic drugs: dimenhydrinate, ondansetron, prochlorperazine, promethazine, scopolamine Antihistamine drugs: diphenhydramine, hydroxyzine Antihypertensive drugs: α-adrenergic agonists (eg, clonidine), β-blockers, calcium channel blockers (especially verapamil), diuretics Antispasmodic drugs: dicyclomine Cation agents: aluminum, bismuth, barium, calcium, iron Chemotherapy: vincristine, cyclophosphamide Resins: cholestyramine, sodium polystyrene sulfonate

Data from Gallegos-Orozco et al,¹ Gray,⁴ Gandell et al,⁸ and Branch and Butt.¹⁴