What is chloramphenicol?

Chloramphenicol (brand names Chloromycetin®, Viceton®) is a broad-spectrum antibiotic used to treat many different gastrointestinal, pulmonary, and urinary bacterial infections, including those caused by anaerobic bacteria (bacteria that do not require oxygen for survival or growth) and Rickettsia (the bacteria that causes Rocky Mountain spotted fever).

It is approved for use in dogs and horses but is used off label (extra label) in cats, rabbits, hedgehogs, rodents, ferrets, birds, and reptiles. Many drugs are commonly prescribed for off-label use in veterinary medicine. “Off label” means the drug is being used in a way that has not been reviewed or approved by the U.S. Food and Drug Administration (FDA) or Health Canada. In these instances, follow your veterinarian’s directions and cautions carefully, as they may be significantly different from those on the label. .

How is chloramphenicol given?

• Chloramphenicol comes as tablets, capsules, liquid suspension, and in an injectable form (chloramphenicol sodium succinate). Injectable forms will be administered by your veterinarian.
• Tablets, capsules, and liquid suspensions should be given by mouth with food. Do not crush pills.
• Measure liquid forms carefully.
• The tablets are extremely bitter and even hiding the tablets in food may not cover the bitter taste. If you are having trouble giving the tablets to your pet, try other forms of the medication.

Chloramphenicol is considered a hazardous drug, and exposure in humans can have serious and irreversible consequences, so it is essential avoid accidental exposure.

• Wear gloves when handling the medication and do not handle if you are pregnant or nursing.
• If your pet vomits after giving this drug, wear gloves while cleaning up.
• DO NOT crush pills, as crushing creates powders that can become airborne, and inhaling this powder is as dangerous as touching or consuming the drug.

This medication will take effect quickly, in about one to two hours, but effects may not be noticeable for a few days.

What if I miss giving my pet the medication?

It is very important to give the medication at the prescribed intervals. Missing a dose can cause the drug not to work properly. If you miss a dose, give it as soon as you remember, and then wait the recommended time for the next dose, as prescribed by your veterinarian However, if it is almost time for the next dose, skip the missed dose and resume the regular dosing schedule. Do not give the pet two doses at once.

Are there any potential side effects?

Chloramphenicol may cause the following side effects:

• Vomiting, diarrhea, and anorexia (decreased appetite)
• Lethargy, bruising, or paleness (with prolonged treatment or higher doses)
• Weakness and lack of muscle coordination resulting in difficulty walking (in dogs)

Monitor cats closely, as they are much more sensitive and more susceptible to experiencing side effects of this drug.

Other side effects may occur. If you notice anything unusual, contact your veterinarian immediately.  This short-acting medication should stop working within 24 hours, although effects can be longer in pets with liver or kidney disease.

Are there any risk factors for this medication?

DO NOT USE chloramphenicol in:

• Dogs used for breeding
• Animals that are pregnant or nursing
• Animals that are very young or very old

USE WITH EXTREME CAUTION in:

• Animals with blood disorders, such as anemia

USE WITH CAUTION in:

• Animals with liver or kidney disease

Do not vaccinate your pet while it is taking this medication.

Are there any drug interactions I should be aware of?

Several medications should be used with caution when given with chloramphenicol, including:

• Barbiturates (e.g., phenobarbital)
• Salicylates (e.g., aspirin)
• Some other antibiotics (e.g., penicillins, cephalosporins)

Be sure to tell your veterinarian about any medications (including vitamins, supplements or herbal therapies) that your pet is taking before starting any treatment.

Is any monitoring needed with this medication?

• Your veterinarian will let you know when and how they want to reassess your pet to ensure the medication is working and not causing side effects.
• Your veterinarian may recommend monitoring the levels of this drug in the blood to ensure the correct amount of medication is administered.
• If long-term use is expected, blood tests, including complete blood counts, may be necessary before treatment begins and every two days during the treatment.
• At home, monitor for any side effects such as those noted above. If any occur, stop using the medication and contact your veterinarian.

How do I store chloramphenicol?

• Store chloramphenicol in a tightly sealed container, at room temperature, below 77°F (25°C).
• Protect from light.

What should I do in case of an emergency?

If you suspect an overdose or an adverse reaction to the medication, call your veterinary office immediately. If they are not available, follow their directions in contacting an emergency facility. Be prepared to provide information about the product and your pet's weight and symptoms. If human exposure to the medication occurs, wash the area thoroughly. If the drug is inhaled, contact your doctor.