The clinical safety of ceftriaxone administered at various doses for time periods ranging from a single injection to up to six weeks was evaluated in 2,640 patients treated in 153 individual studies. The incidence of clinical adverse effects was greatest for gastrointestinal (3.45 percent), hypersensitivity (2.99 percent), and local (1.86 percent) reactions. When the pediatric population was analyzed separately, the incidence of gastrointestinal and hypersensitivity reactions was 5.63 and 3.3 percent, respectively; all other reactions occurred in fewer than 1 percent of patients. The frequency of adverse effects for the once-daily and twice-daily dosing regimens was comparable, except for a statistically significant increase in local reactions when ceftriaxone was administered twice daily. When ceftriaxone was compared directly with other antibiotic regimens, the incidence of clinical adverse effects was similar. Ceftriaxone appears to be safe and well tolerated from a clinical standpoint.