Since the syndrome is due to the accumulation of chloramphenicol, the signs and symptoms are dose related. According to Kasten's review published in the Mayo Clinic Proceedings, a serum concentration of more than 50 μg/mL is a warning sign, while Hammett-Stabler and John states that the common therapeutics peak level is 10-20 μg/mL and is expected to achieve after 0.5-1.5 hours of intravenous administration in their review of antimicrobial drugs. The common onset of signs and symptoms are 2 to 9 days after the initiation of the medication, which allows the serum concentration to build up to reach the toxic concentration above. Common signs and symptoms include loss of appetite, fussiness, vomiting, ashen gray color of the skin, hypotension (low blood pressure), cyanosis (blue discoloration of lips and skin), hypothermia, cardiovascular collapse, hypotonia (muscle stiffness), abdominal distension, irregular respiration, and increased blood lactate.
