Medically Reviewed on 5/28/2022

Generic Name: colistin

Brand and Other Names: colistimethate sodium, Coly Mycin M, polymyxin E

Drug Class: Antibiotics, Other

What is colistin, and what is it used for?

Colistin is an antibiotic used to treat acute and chronic bacterial infections from susceptible strains of certain gram-negative bacteria. Gram-negative bacteria are structurally different from gram-positive bacteria, with an additional cell membrane that gram-positive bacteria lack. The two types of bacteria are identified by whether they get dyed or not in the Gram stain lab test. 

Colistin belongs to the polymyxin class of antibiotics and is used as the last line of defense against serious infections, including those caused by multidrug resistant organisms. Colistin is the active component of colistimethate sodium which is administered through an intravenous (IV) or intramuscular (IM) injection. Colistin binds to fatty molecules on the cell membranes of gram-negative bacteria and causes leakage of cell contents leading to bacterial cell death.

Colistin has a narrow spectrum of activity limited to a subset of gram-negative bacteria, and is ineffective against gram-positive bacteria. Gram-negative bacteria that are susceptible to colistin include:


  • Do not use to treat patients with a history of hypersensitivity to colistin or any of its components.
  • Use of inhaled colistimethate (off-label route) may result in bronchoconstriction. Use with caution in patients with hyperactive airways. Consider administration of a bronchodilator such as albuterol within 15 minutes prior to administration of colistin.
  • Colistin is toxic to the central nervous system and may cause temporary neurological disturbances such as tingling, numbness, dizziness, vertigo and slurred speech. Advise patients to avoid activities that require mental alertness.
  • Colistin is toxic to the kidneys. Discontinue therapy if there are signs of impaired kidney function.
  • Respiratory arrest has been reported with colistin use. The risk increases with impaired kidney function, use with caution in patients with kidney disease. Respiratory arrest risk also increases in patients with myasthenia gravis and concurrent use of anesthetics or other neuromuscular blocking drugs.
  • Prolonged colistin use may cause fungal or bacterial superinfection, including colon inflammation (pseudomembranous colitis) and Clostridium difficile-associated diarrhea (CDAD).


Bowel regularity means a bowel movement every day. See Answer

What are the side effects of colistin?

Common side effects of colistin include:

  • Central nervous system effects including:
    • Dizziness
    • Numbness and prickling sensation of skin (paresthesia)
    • Tingling of extremities and tongue
    • Seizures
    • Slurred speech
    • Vertigo
  • Toxicity to the kidney (nephrotoxicity)
  • Decreased urine output
  • Increased blood urea nitrogen (BUN)
  • Elevated creatinine

Less common side effects of colistin 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 colistin?

Powder for Injection

  • 150 mg/vial

Susceptible Infections

Adult and pediatric patients older than 12 years of age

Children under 12 years of age: Safety and efficacy not established

Dosage expressed in terms of colistin base

  • 2.5-5 mg/kg/day divided every 6-12 hours intravenously/intramuscularly (IV/IM); not to exceed 5 mg/kg/day

Dosage Modifications

Renal Impairment

  • CrCl greater than 80 mL/minute: No dosage adjustment required
  • CrCl 50-79 mL/minute: 2.5-3.8 mg/kg/day IV/IM divided every 12 hours
  • CrCl 30-49 mL/minute: 2.5 mg/kg/day IV/IM once daily or divided every 12 hours
  • CrCl 10-29 mL/minute: 1.5 mg/kg IV/IM every 36 hours

Other Indications and Uses

  • Gram-neg. infection (e.g., Enterobacter aerogenes, E. coli, Klebsiella, Pseudomonas) unresponsive to other antibiotics
  • Multi-drug resistant gram-negative infection


  • Colistin overdose may cause neuromuscular adverse effects such as balance, coordination and speech impairment (ataxia), abnormal skin sensations (paresthesia), lethargy, dizziness, and confusion.
  • Severe overdose can cause acute kidney failure, respiratory paralysis, and death.
  • Colistin overdose is treated with symptomatic and supportive care.

What drugs interact with colistin?

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.

  • Colistin has no known severe interactions with other drugs.
  • Serious interactions of colistin include:
  • Moderate interactions of colistin include:
  • Mild interactions of colistin include:

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 colistin use in pregnant women and animal studies show evidence of fetal harm. Colistin crosses the human placenta and should be used during pregnancy only if the potential benefits outweigh potential risks to the fetus.
  • Colistin is excreted in breast milk. Use with caution in nursing mothers.

What else should I know about colistin?

  • Diarrhea is a common problem with antibiotic treatments which should resolve with the completion of the therapy; seek medical help if you have watery or bloody stools, with or without stomach cramps and fever; can develop even up to two months after the last dose of antibiotic.
  • Colistin may impair mental and physical abilities. Do not engage in activities such as driving or operating heavy machinery.

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Colistin is an antibiotic used to treat acute and chronic bacterial infections from susceptible strains of certain gram-negative bacteria. Colistin is toxic to the kidneys. Discontinue therapy if there are signs of impaired kidney function. Common side effects of colistin include dizziness, numbness and prickling sensation of skin (paresthesia), tingling of extremities and tongue, seizures, slurred speech, vertigo, decreased urine output, and increased blood urea nitrogen (BUN), and elevated creatinine.

Treatment & Diagnosis

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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 5/28/2022