Objective To evaluate the suggested association between tetracycline and acute pancreatitis in a large pharmacoepidemiological study.

Design The use of tetracycline in relation to the risk of acute pancreatitis was examined in a nationwide case–control study of people aged 40–84 years between 2006 and 2008 in Sweden. The Swedish Patient Register was used to identify 6161 cases of first-episode acute pancreatitis. The Register of the Total Population was used to randomly select 61 637 control subjects from the general population using frequency-based density sampling, matched for age, sex, and calendar year. Tetracycline use was defined as ‘current’, ‘recent’, ‘past’ or ‘former’ if the drug had been dispensed 0–30 days, 31–180 days, 181–365 days or 1–3½ years before the index date, respectively. The risk of acute pancreatitis was estimated by unconditional logistic regression, providing ORs with 95% CIs, adjusted for potential confounding factors.

Results There was a 60% increased risk of acute pancreatitis among current users of tetracycline after adjustment for potential confounders (OR=1.6, 95% CI 1.2 to 2.1). There was no increased OR for any category of previous use.

Conclusion Current use of tetracycline is associated with an increased risk of acute pancreatitis, verifying previous case reports.