Monoarthritis Induced by Bupropion Hydrochloride.

Bupropion hydrochloride is an inhibitor of dopamine and norepinephrine, which is commonly prescribed for major depression, smoking cessation, and bipolar depression. Here we report a highly unusual case of bupropion induced knee monoarthritis in a bipolar depression patient. With bupropion XL 150 mg for 2 weeks, her left knee began to swell; at the third week, this condition was worsening. The aggravation of the left knee effusion stopped after the discontinuation of bupropion XL. The effusion and swelling disappeared after 15 ml of synovial fluid was drawn out and the effusion has never returned. Analysis of the synovial fluid showed noninflammatory effusion. Her left knee swelling was most likely due to angioedema caused by bupropion XL.