We report a female patient who repeatedly developed
pancreatitis after trimethoprim-sulfamethoxazole
(TMP/SMX) use. During childhood she had undergone
an ureterosigmoidostomy after which she had been on
TMP/SMX 480 mg daily as prophylaxis for pyelonephritis
for many years. The patient presented with abdominal
pain caused by acute pancreatitis. No other cause, except for TMP/SMX use, could be identified. A causal relationship was confirmed by relapse of the pancreatitis after rechallenge. Our case is unique in demonstrating that acute pancreaitis related to the use of TMP/SMX may occur even after long-term treatment. We advise that the medication is discontinued immediately if a causal relationship with pancreatitis is suspected.