Drugs associated with constipation
Anticholinergics
Antihistamines: diphenhydramine, hydroxyzine
Antidepressants: TCAs(e.g, amitriptyline, nortriptyline, clomipramine, desipramine, imipramine, doxepin), paroxetine, etc.
Anti-Parkinson drugs: amantadine, bromocriptine, pramipexole, Trihexyphenidyl, Benztropine
Antiemetic drugs / Antivertigo: dimenhydrinate, ondansetron, 5HT3 antagonists, prochlorperazine, promethazine, scopolamine
Antipsychotic drugs: 1st generation (Chlorpromazine, fluphenazine, loxapine, methotrimeprazine (levomepromazine), thioridazine, trifluoperazine); 2nd Gen (Clozapine)
Antispasmodics: Dicyclomine, atropine, belladonna-containing medications, Clidinium-chlordiazepoxide, hyoscyamine, glycopyrrolate, homatropine, methscopolamine, propantheline, scopolamine (hyoscine)
Gastrointestinal antispasmodics
Bladder antimuscarinics (anticholinergics for overactive bladder): Oxybutynin, tolterodine, Darifenacin, fesoterodine, flavoxate, solifenacin, trospium
Skeletal muscle relaxants: Cyclobenzaprine, orphenadrine, tizanidine, etc.
Antiarrhythmic
Analgesics:
NSAIDs (ibuprofen, Naproxen, etc.), opioids
Cation-containing drugs
Iron supplements
Aluminum (antacids, sucralfate)
Barium, bismuth,
Calcium
Resins: cholestyramine, sodium polystyrene sulfonate
Neurally active agents
Antihypertensives: α-adrenergic agonists (eg, clonidine), β-blockers, calcium channel blockers (especially verapamil, diltiazem), diuretics (2/2 to fluid loss)Ganglionic blockers
Calcium channel blockers e.g. Verapamil, diltiazem
Vinca alkaloids (chemotherapy meds like vincristine)
Ganglionic blockers
Antidiarrheal drugs: diphenoxylate/atropine, loperamide
Anticonvulsant drugs: gabapentin, phenytoin, pregabalin
Further Reading
JAMA internal medicine. 2015;175(3):401-407. Cumulative Use of Strong Anticholinergic Medications and Incident Dementia. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4358759/
Can Fam Physician. 2015 Feb; 61(2): 152–158.