The Short Answer
Valproic acid (Depakote®), azathioprine (Imuran®), sulfonamides (Bactrim®), thiazide diuretics (HCTZ), and corticosteroids are the top culprits, accounting for roughly 60–70% of all drug-induced pancreatitis cases [9]. Onset typically occurs 1–4 weeks after starting the medication.
Valproic acid, an anti-seizure and mood-stabilizing drug, triggers pancreatitis in 1–2 per 1,000 patients—the highest rate among all medications [9]. Azathioprine (used for autoimmune diseases and transplant rejection) and sulfonamide antibiotics (Bactrim®, Septra®) follow closely. Thiazide diuretics like hydrochlorothiazide (HCTZ), commonly prescribed for high blood pressure, cause pancreatitis in 0.2–0.5 per 1,000 patients.
The mechanism varies by drug class: valproic acid damages pancreatic cell membranes directly, while sulfonamides trigger an allergic immune reaction [9]. Thiazides may cause metabolic shifts that activate pancreatic enzymes prematurely. Corticosteroids (prednisone, dexamethasone) can inflame the pancreas through immune dysregulation, especially at high doses or with prolonged use.
Other notable culprits include pentamidine (for PCP pneumonia), didanosine (HIV medication), mesalamine (for inflammatory bowel disease), and certain cancer drugs like L-asparaginase [9]. If you're on any of these medications and develop sudden belly pain, contact your doctor immediately—don't assume it's food poisoning or a stomach bug.