Drug-induced lupus.

Drug-induced lupus (DIL) is a rare adverse reaction to a large variety of drugs with features resembling those of idiopathic systemic lupus erythematosus (SLE). It usually develops only after months and, quite commonly, years of treatment with the offending agent, although latencies of days or weeks have been described in some instances. There are some indications that the risk of DIL can increase with higher daily and cumulative doses and with longer duration of therapy. There are no definitive and commonly accepted diagnostic criteria for DIL, but the following guidelines have been proposed: (a) sufficient and continuing exposure to a specific drug, (b) at least one symptom compatible with SLE, (c) no history suggestive of SLE before starting the drug, and (d) resolution of symptoms within weeks (sometimes months) after discontinuation of the putative offending agent. In addition, it is frequently suggested that the presence of ANA is required for the diagnosis of DIL. However, negative ANA test results should not automatically preclude such a diagnosis, particularly if a patient has other autoantibodies associated with SLE/DIL.