Drug-induced lupus erythematosus (DIL) is a syndrome, similar to systemic lupus erythematosus, caused by any of various drugs, such as hydralazine, procainamide, isoniazid, D-penicillamine, and chlorpromazine. It usually resolves following withdrawal fo the offending drug.
Approximately 10% of idiopathic SLE are drug-induced. The incidence in the USA is 15,000 to 20,000 new cases annually.
75% of patients receiving procainamide therapy develop ANA within 1 year of treatment. Nearly 100% develop ANA within 2 years, most of them asymptomatic but 10-30% develop drug-induced lupus.