Drug-induced arthritis and arthralgia.

In the differential diagnosis of arthritis and arthralgia, one must consider the possibility of adverse drug reactions being responsible. The distinction between primary cause and secondary aggravation of a pre-existing condition is often difficult and sometimes impossible to make; for instance, oral contraceptives may seem on occasion to precipitate pre-existing rheumatoid arthritis and systemic lupus erythematosus and also to cause temporary symptoms resembling these disorders in previously normal subjects. In addition, serum sickness type reactions, myopathies, electrolyte and fluid disturbances, pseudosclerodermas, bone lesions and local reactions to intra-articular injections have been described. One should therefore be aware of the possibility of drug-induced syndromes resembling rheumatoid arthritis, systemic lupus erythematosus, periarthritis of the shoulders, progressive systemic sclerosis, and other rheumatic and arthritic disorders. Though rarely severe or incapacitating, they may cause considerable diagnostic confusion.