May cause drug-induced lupus-like syndrome. Use with caution in coronary artery disease (risk of precipitation of angina attacks and/or MI), pulmonary hypertension (may cause hypotension), or in severe renal impairment. May cause systemic lupus erythematosus (e.g. glomerulonephritis) or rheumatoid arthritis. Some formulations contain sulfites which may cause allergic-type reactions (including anaphylaxis and life-threatening or less severe asthmatic episodes) in certain susceptible individuals. May increase pulmonary artery pressure in mitral valvular disease. Orthostatic hypotension possible (use with caution in cerebrovascular accidents, patients who may be volume-depleted, those with pre-existing hypotension, or those receiving other hypotensive agents). May paradoxically reduce pressor response to epinephrine. Peripheral neuritis might occur (e.g. numbness, paresthesia, tingling). Blood dyscrasias possible (e.g. agranulocytosis, decreased hemoglobin and erythrocytes, leukopenia, thrombocytopenia with or without purpura).