Regimens of >600 mg once or twice weekly associated with high incidence of adverse reactions including flu-like syndrome. May cause thrombocytopenia, leukopenia, or anemia with regimens >600 mg once or twice weekly. Hypersensitivity reactions occurred in patients taking >600 mg once or twice weekly. Prolonged use may result in fungal or bacterial superinfection, including C. difficile-associated diarrhea and pseudomembranous colitis. Use with caution in history of alcoholism (even if ethanol consumption is discontinued during therapy), and in liver impairment. Do not use for meningococcal disease, only for short-term treatment of asymptomatic carrier states. Use with caution in porphyria (exacerbations reported due to enzyme-inducing properties), and in patients receiving concurrent medications associated with hepatotoxicity. Do not administer I.V. form via I.M. or SubQ routes. Soft contact lenses should be removed during therapy (permanent staining may occur). Urine, feces, saliva, sweat, tears, and CSF may be discolored to red/orange.