Anaphylactic reactions to drugs In contrast to the profound immunodeficiency that characterizes most manifestations of AIDS, a host of immunologic and rheumatologic disorders are common in patients with HIV infection. Ceainly the most common such reaction is cutaneous manifested sensitivity to the antibiotics required for treatment of the secondary infections so common in these patients. Some 65% of patients who receive trimethoprim-sulfamethoxazole develop an erythematous morbilliform pruritic eruption. Founately, anaphylaxis is very rare, and desensitization is possible. Patients infected with HIV may develop diseases that resemble classic autoimmune diseases in non-HIV-infected persons. A variant of Sjogren's syndrome characterized by dry eyes, dry mouth, and lymphocytic infiltrates of the salivary gland and lung may be seen. HIV -associated ahropathy is characterized by a nonerosive oligoaicular ahritis that generally involves the large joints. Widespread musculoskeletal pain of at least 3 months' duration with tender points, typical of fibromyalgia, may occur in up to 10% of HIV-infected IV drug abusers. Reactive ahritides, such as Reiter's syndrome or psoriatic ahritis, have also been described.