Merck Manual

Please confirm that you are a health care professional

honeypot link



Brian J. Werth

, PharmD, University of Washington School of Pharmacy

Last full review/revision May 2020
Click here for Patient Education


Chloramphenicol is well absorbed orally. Parenteral therapy should be IV.

Chloramphenicol is distributed widely in body fluids, including cerebrospinal fluid, and is excreted in urine. Because of hepatic metabolism, active chloramphenicol does not accumulate when renal insufficiency is present.

Indications for Chloramphenicol

Chloramphenicol has a wide spectrum of activity against

Because of bone marrow toxicity, the availability of alternative antibiotics, and the emergence of resistance, chloramphenicol is no longer a drug of choice for any infection, except for

However, when chloramphenicol has been used to treat meningitis caused by relatively penicillin-resistant pneumococci, outcomes have been discouraging, probably because chloramphenicol has poor bactericidal activity against these strains.

Contraindications to Chloramphenicol

Chloramphenicol is contraindicated if another drug can be used instead.

Use During Pregnancy and Breastfeeding

Use of chloramphenicol during pregnancy results in fetal drug levels almost as high as maternal levels. Gray baby syndrome is a theoretical concern, particularly near term, but there is no clear evidence of fetal risk.

Chloramphenicol enters breast milk. Safety during breastfeeding has not been determined.

Adverse Effects of Chloramphenicol

Adverse effects of chloramphenicol include

  • Bone marrow depression (most serious)

  • Nausea, vomiting, and diarrhea

  • Gray baby syndrome (in neonates)

There are 2 types of bone marrow depression:

Hypersensitivity reactions are uncommon. Optic and peripheral neuritis may occur with prolonged use.

The neonatal gray baby syndrome, which involves hypothermia, cyanosis, flaccidity, and circulatory collapse, is often fatal. The cause is high blood levels, which occur because the immature liver cannot metabolize and excrete chloramphenicol. To avoid the syndrome, clinicians should not give infants 1 month of age > 25 mg/kg/day initially, and doses should be adjusted based on blood levels of the drug.

Click here for Patient Education
NOTE: This is the Professional Version. CONSUMERS: Click here for the Consumer Version
Professionals also read
Test your knowledge
Rat-Bite Fever
Streptobacillary rat-bite fever is caused by Streptobacillus moniliformis, an organism found in the oropharynx of healthy rats. If a patient is bitten by an infected rat, symptoms can begin to develop within a period of 1 to 22 days. Which of the following symptoms of this disease tends to develop about 3 days after the initial symptoms?
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID

Also of Interest