Doxycycline (Vibramycin) is the antibiotic of choice for adults and children. Doxycycline is contraindicated in pregnant women, although it may be considered in life-threatening situations when clinical suspicion of tick-borne illness is high. The recommended dosage of doxycycline is 100 mg orally or intravenously twice a day for adults, and mg per kg orally or intravenously twice a day for children who weigh less than 100 lb ( kg). Although the optimal duration of therapy has not been established, a five- to seven-day course is recommended for RMSF and HME after the fever subsides. A 10- to 14-day course is recommended for HGA. Chloramphenicol (Chloromycetin) may be used as an alternative to doxycycline; however, this drug may cause side effects, and monitoring of blood indices may be needed.