Medically Reviewed on 4/20/2022

Generic Name: chloramphenicol

Brand and Other Names: chloramphenicol IV, Chloromycetin (discontinued) 

Drug Class: Antibiotics, Other

What is chloramphenicol, and what is it used for?

Chloramphenicol is a synthetic broad-spectrum antibiotic used to treat severe systemic infections caused by susceptible strains of bacteria. Chloramphenicol topical formulations were used in the past to treat superficial eye and ear infections.

Because of its serious adverse effects, oral and topical chloramphenicol formulations are no longer available in the U.S. and intravenous chloramphenicol is used only for acute and serious infections that cannot be treated with less toxic alternative antibiotics.

Chloramphenicol prevents bacterial growth by binding to the bacterial ribosomes (cellular particles that synthesize proteins) and preventing the protein synthesis essential for the bacteria to grow. This damages the bacterial protein and cell membrane, resulting in bacterial death.

Chloramphenicol is effective against a wide range of gram-positive and gram-negative bacteria. Gram-negative and gram-positive bacteria are structurally different, and the types are identified by whether the bacteria get dyed or not in the Gram stain lab test.

Chloramphenicol is used for the treatment of serious infections including:

Organisms susceptible to chloramphenicol include:


  • Do not use chloramphenicol in the following circumstances:
    • In patients who have had previous hypersensitivity or toxic reaction to it
    • Trivial bacterial infections
    • Viral infections
    • For prevention (prophylaxis) of bacterial infections
  • Chloramphenicol can cause bone marrow suppression (myelosuppression) that may result in serious and fatal blood disorders (dyscrasias) after both short-term and long-term therapy; use only for serious infections, monitor complete blood count (CBC) frequently and discontinue upon evidence of myelosuppression
  • Avoid repeated courses of chloramphenicol therapy, if at all possible
  • Do not continue treatment longer than required to cure the disease with little or no risk of relapse of the disease
  • Elevated blood levels of chloramphenicol in infants can lead to gray baby syndrome, characterized by grayish skin, abdominal distention, and circulatory collapse that can lead to death; premature infants and newborns are at the highest risk because their kidneys and liver are immature and not fully functional; use with extreme caution
  • Prolonged use may result in fungal or bacterial superinfection; monitor and take appropriate measures if nonsusceptible organisms appear
  • Impaired liver or kidney function may cause excessive blood levels of chloramphenicol even at recommended dose; determine blood concentration at appropriate intervals and adjust dosage accordingly
  • Use with caution in patients with glucose 6-phosphate dehydrogenase deficiency


Bacterial Infections 101: Types, Symptoms, and Treatments See Slideshow

What are the side effects of chloramphenicol?

Common side effects of chloramphenicol include:

This is not a complete list of all side effects or adverse reactions that may occur from the use of this drug.

Call your doctor for medical advice about serious side effects or adverse reactions. You may also report side effects or health problems to the FDA at 1-800-FDA-1088.

What are the dosages of chloramphenicol?

Injectable solution

  • 1,000 mg/vial


Serious Infections Caused by Susceptible Strains

  • 50 mg/kg/day intravenously divided every 6 hours
  • In exceptional cases, patients with moderately resistant organisms or severe infections may require increased dosage up to 100 mg/kg/day; decrease these high doses as soon as possible

Other Indications and Uses

  • Use only as an alternative for treatment of meningitis, typhoid, or rickettsial infection


Systemic Infections

Infants and children

  • As in adults; when adequate cerebrospinal fluid concentrations are desired, may require up to 100 mg/kg/day; however, should reduce dose to 50 mg/kg/day as soon as possible

Infants and children with suspected immature metabolic functions

  • 25 mg/kg/day divided every 6 hours will usually produce therapeutic concentrations of the drug in the blood

Neonates (Infants younger than 28 days)

Loading dose (LD)

  • 20 mg/kg intravenously once; give maintenance dose 12 hours after loading dose

Maintenance Dose

  • Infants younger than 7 days old: 25 mg/kg/day intravenously every 24 hours
  • Infants over 7 days old, less than 2000 g: 25 mg/kg/day intravenously every 24 hours
  • Infants over 7 days old, over 2000 g: 50 mg/kg/day intravenously every 12 hours

Other Information

  • Peaks 10-20 mg/l, troughs 5-10 mg/l


  • Chloramphenicol overdose can be fatal. Overdose is more likely to affect infants because their liver and kidneys are immature. Symptoms of overdose include
  • Use utmost precaution to avoid overdose; overdose may be treated with immediate discontinuation of chloramphenicol and intensive supportive care including resuscitation and other life-saving measures.

What drugs interact with chloramphenicol?

Inform your doctor of all medications you are currently taking, who can advise you on any possible drug interactions. Never begin taking, suddenly discontinue, or change the dosage of any medication without your doctor’s recommendation.

  • Severe interactions of chloramphenicol include:
  • Chloramphenicol has serious interactions with at least 123 different drugs.
  • Chloramphenicol has moderate interactions with at least 89 different drugs.
  • Chloramphenicol has minor interactions with at least 42 different drugs.

The drug interactions listed above are not all of the possible interactions or adverse effects. For more information on drug interactions, visit the RxList Drug Interaction Checker.

It is important to always tell your doctor, pharmacist, or health care provider of all prescription and over-the-counter medications you use, as well as the dosage for each, and keep a list of the information.

Check with your doctor or health care provider if you have any questions about the medication.

Pregnancy and breastfeeding

  • There are no adequate and well-controlled studies on chloramphenicol use in pregnancy; it is not known whether it can cause fetal harm
  • Gray baby syndrome has occurred in premature infants and newborns receiving chloramphenicol
  • Use chloramphenicol in pregnancy only if the potential benefit outweighs the potential risk to the fetus
  • Chloramphenicol is excreted in breast milk; avoid use in nursing mothers; discontinue either the drug or nursing

Subscribe to MedicineNet's General Health Newsletter

By clicking Submit, I agree to the MedicineNet's Terms & Conditions & Privacy Policy and understand that I may opt out of MedicineNet's subscriptions at any time.


Chloramphenicol is a synthetic broad-spectrum antibiotic used to treat severe systemic infections, including bacterial meningitis, bacterial blood infection (bacteremia), typhoid fever, Rickettsial infections, and exacerbation of cystic fibrosis. Common side effects of chloramphenicol include bone marrow depression, blood disorders (including anemia), headache, confusion, delirium, depression, nausea, vomiting, diarrhea, and others. Avoid use in nursing mothers; discontinue either the drug or nursing. Consult your doctor if pregnant.

Treatment & Diagnosis

Medications & Supplements

Health Solutions From Our Sponsors

FDA Logo

Report Problems to the Food and Drug Administration

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.

Medically Reviewed on 4/20/2022