Chloramphenicol for Cats: Dosage, Duration, and Safety

Name: Chloramphenicol for Cats: Dosage, Duration, and Safety
Creator: Dr. Zubair Khalid

By Dr. Zubair Khalid, DVM, MS, PhD · 2026-10-03

Chloramphenicol for cats dosage is not something you can safely guess at home. In one case series of 12 cats with complicated infections, veterinarians prescribed a median oral dose of 13.3 mg/kg (range 9.1 to 34.7 mg/kg) every 12 hours, for a median of 14.5 days [1]. Your own cat's dose and length of treatment depend on the infection, the bacteria involved, and your cat's overall health, so only your veterinarian should set the numbers.

This article is educational and is not a substitute for veterinary diagnosis or treatment.

Quick Answer

Chloramphenicol is a prescription antibiotic used in cats mainly when infections are resistant to safer first-choice drugs, or when no other oral option works [1].
A typical oral dose in a recent case series was about 13.3 mg/kg every 12 hours, but your veterinarian will calculate the exact amount for your cat's weight and condition [1].
Treatment commonly runs about two weeks, though the median of 14.5 days in that case series is a middle figure, not a rule [1].
Chloramphenicol is dangerous to people. Wear gloves when giving it, wash your hands afterward, and never handle capsules or liquid with bare skin if you are pregnant, trying to conceive, or have a weakened immune system.
Call your veterinarian right away if your cat vomits repeatedly, stops eating, seems weak, or develops any bleeding or bruising.

What Chloramphenicol Is and What Veterinarians Use It For

Chloramphenicol is an antibiotic that slows bacterial growth by blocking how bacteria build proteins. It covers a wide range of organisms, which is one reason it stays in the veterinary toolbox even though safer antibiotics exist.

In cats, veterinarians reach for it mostly in tough situations. In a review of 12 client-owned cats treated between 2015 and 2023, the infections involved skin, the urinary tract, and multiple body systems at once [1]. Eleven of the 12 cats had already received at least one other antibiotic in the 30 days before starting chloramphenicol [1]. The targeted bacteria were often multidrug-resistant organisms, including meticillin-resistant Staphylococcus species and multidrug-resistant Enterococcus faecium, for which no alternative oral antibiotic was available [1]. Nine of the 12 cats reached either a bacteriologic or clinical cure [1].

That pattern tells you something useful. Chloramphenicol is usually a backup drug, reserved for infections that did not respond to safer options. It is also one of the few antibiotics that can be given by mouth for some resistant infections when injectable drugs would otherwise be the only choice [1].

If your veterinarian prescribed a different antibiotic, such as amoxicillin, the dosing logic is similar in one way, the drug is matched to your cat's weight and the specific infection. You can read more about that class of drugs in our guide to Amoxicillin Dog Cat Dose: Broad-Spectrum Antibiotic Weight-Based Guide.

How Chloramphenicol Works

Bacteria need working ribosomes, which are tiny protein factories inside the cell, to survive and multiply. Chloramphenicol binds to part of the bacterial ribosome and stops it from assembling new proteins. Without those proteins, the bacteria cannot grow or divide, and your cat's immune system can clear them.

This is why chloramphenicol tends to work best when given on a steady schedule. The goal is to keep enough drug in your cat's bloodstream around the clock to keep the bacteria suppressed. Skipping doses or stretching the interval gives bacteria room to recover, which is also how resistance develops.

Because the drug targets a bacterial structure that differs from human and feline cells, it is selective, but not perfectly so. That imperfect selectivity is part of why side effects happen, especially in the bone marrow.

Chloramphenicol for Cats Dosage: How Much and How Long

Who Decides the Dose

Your veterinarian decides. There is no safe home dose you can calculate from a chart. The dose depends on your cat's weight, the site of infection, how sick your cat is, kidney and liver function, and what other medications your cat takes.

For context, the median dose in the published case series was 13.3 mg/kg given by mouth every 12 hours, with a range from 9.1 to 34.7 mg/kg [1]. That range is wide because different infections and different cats need different exposure. Your veterinarian may land anywhere in or near that range, or choose a different schedule entirely.

How It Is Given

Chloramphenicol comes as oral capsules, oral liquid, and, in some cases, as a topical ointment or ophthalmic preparation for eye and skin use. Oral forms are the most common for systemic infections [1].

A few practical points:

Give the medication at the same times each day. Twice-daily dosing means roughly 12 hours apart [1].
Give with a small amount of food if your cat gets an upset stomach, unless your veterinarian says otherwise.
Do not crush, split, or open capsules unless your veterinarian tells you to. The powder is a human exposure risk.
If you are using an eye ointment, do not let the tube tip touch your cat's eye or eyelid, and do not share the tube with any person.

Chloramphenicol Ointment for Cats Dosage

Ointments and ophthalmic preparations are dosed differently from oral drugs. There is no standard milligram-per-kilogram figure for topical use that applies across products, because absorption through skin and eyes varies by formulation and by how much surface area is treated. Your veterinarian will tell you how often to apply it and for how many days.

For eye infections specifically, follow the exact schedule your veterinarian gives you. Do not extend treatment on your own because the eye looks better, and do not stop early because it looks the same. Both mistakes can lead to relapse or resistance.

How Many Days

In the case series, cats received chloramphenicol for a median of 14.5 days [1]. Some needed less, some needed more. Your veterinarian will set a stop date and may want a recheck before you reach it.

Never stop early just because your cat seems normal again. Never continue past the prescribed end date without checking in. If your cat is still showing symptoms when the course ends, call your veterinarian instead of refilling on your own.

Missed Doses

If you miss a dose, give it as soon as you remember, unless it is almost time for the next one. In that case, skip the missed dose and go back to your regular schedule. Do not double up to catch up. If you miss more than one dose in a row, call your veterinarian for guidance.

Chloramphenicol for Cats Side Effects

Chloramphenicol can cause problems in cats, and some of them are serious. The table below separates the common from the dangerous.

Side effect	How common or serious	What to do
Vomiting, diarrhea, reduced appetite	Common and usually mild	Offer small bland meals, call your veterinarian if it lasts more than a day or your cat stops eating
Lethargy or weakness	Can be mild or a sign of something worse	Call your veterinarian the same day
Bone marrow suppression (low blood cell counts)	Serious, can cause anemia, bleeding, or infections	Stop the drug only if your veterinarian tells you to, and report bruising, pale gums, or bleeding right away
Neurologic signs such as wobbliness or tremors	Uncommon but serious	Treat as an emergency
Allergic reaction, facial swelling, hives, trouble breathing	Rare but life threatening	Emergency visit immediately

Antibiotics in general can poison cats when the dose is wrong or when a cat gets into a human prescription. Signs can range from gastrointestinal upset to metabolic problems to central nervous system damage [2]. If you think your cat swallowed the wrong antibiotic or too much of the right one, contact your veterinarian and Pet Poison Helpline at (855) 764-7661 right away [2].

Treatment for antibiotic poisoning at a clinic may include inducing vomiting and giving intravenous fluids, and the plan depends on the drug, the dose, and how long ago it was swallowed [2].

Who Should Not Take It and What Interacts With It

Chloramphenicol is not for every cat. Your veterinarian will weigh the risks carefully if your cat:

Has known bone marrow disease or a low blood cell count
Has significant liver disease, since the liver processes this drug
Is pregnant or nursing
Is already taking other drugs that suppress the bone marrow or affect liver enzymes

Tell your veterinarian about every medication, supplement, and topical product your cat receives, including flea and tick preventives, heartworm products, and anything you give for behavior or allergies. Some products are dosed by weight and can interact with how your cat handles other drugs [3].

If your cat takes medication for another condition, such as hyperthyroidism, timing and monitoring matter. Our article on Methimazole Cat Dose: Feline Hyperthyroidism Dose and Monitoring explains how those rechecks work.

Also be careful with over-the-counter human products. Some, like antihistamines, have narrow safety margins in cats, as covered in Can You Give Your Cat Benadryl? Dosage and Safety Guide.

Human Safety: Handling Chloramphenicol

This is the part many owners are not warned about clearly enough. Chloramphenicol can cause serious, even fatal, blood disorders in people. The risk is small with occasional contact, but it is real, and it is higher for certain groups.

Follow these rules every time you give the medication:

Wear disposable gloves when handling capsules, tablets, or liquid.
Wash your hands thoroughly with soap and water afterward, even if you wore gloves.
Never open capsules or crush tablets unless your veterinarian specifically instructs you to.
Keep the medication locked away from children and pets.
If you are pregnant, planning a pregnancy, or have a weakened immune system, ask your veterinarian whether someone else in the household can give the doses.
If powder or liquid gets on your skin, wash the area right away with soap and water.
If you accidentally swallow any of it, call your own doctor or a poison control center for people immediately.

Store the medication as directed on the label. Most forms need to be kept at room temperature, away from moisture and heat. Do not save leftover antibiotic for a future illness, and do not give it to another pet or person.

Overdose and When to Call for Help

An overdose can happen in a few ways. Your cat may chew into a pill bottle. A dose may be measured wrong. Or your cat may eat a human prescription that was left out.

Signs of antibiotic poisoning in cats can include gastrointestinal upset, metabolic problems, and central nervous system damage [2]. If you suspect an overdose, do not wait for symptoms. Call your veterinarian and Pet Poison Helpline at (855) 764-7661 for immediate guidance [2].

When you call, have this information ready: the name of the drug, the strength, the dose your cat received, the time it happened, and your cat's weight [2]. That information helps the veterinarian decide whether to induce vomiting, start intravenous fluids, or take another approach [2].

Never try to make your cat vomit at home unless a veterinarian tells you to.

Limitations and When to Contact a Veterinarian

This article gives general information, not a treatment plan. Every cat is different, and your veterinarian is the only person who can decide whether chloramphenicol is right for your cat and at what dose.

Call your veterinarian the same day if your cat:

Vomits more than once or has diarrhea for more than 24 hours
Refuses food for more than a day
Seems unusually tired or weak
Develops a new symptom while on the medication

Go to an emergency clinic right away if your cat:

Has trouble breathing, swelling of the face, or hives
Collapses, has a seizure, or shows tremors
Has pale gums, unexplained bruising, or bleeding from the nose, gums, or rectum
Cannot stand or seems disoriented

Schedule a routine recheck if your cat finished the course but symptoms are returning, or if your veterinarian wants blood work to check blood cell counts during or after treatment.

Frequently Asked Questions

Can I give my cat chloramphenicol without a prescription?

No. Chloramphenicol is a prescription antibiotic, and giving it without veterinary guidance risks the wrong dose, the wrong duration, and serious side effects. It also contributes to antibiotic resistance, which makes future infections harder to treat.

Is chloramphenicol safe for kittens?

Kittens are more vulnerable to drug side effects in general, and chloramphenicol's effects on bone marrow make it a higher-risk choice in young animals. Your veterinarian will decide whether the benefit outweighs the risk for your kitten's specific infection.

Can chloramphenicol eye ointment be used for other eye problems?

No. Eye ointments are prescribed for a specific diagnosis, and using them for a different problem can delay correct treatment or make things worse. If your cat's eye looks red, cloudy, or painful, have it examined instead of reaching for an old tube.

What should I do if I miss giving a dose?

Give the missed dose as soon as you remember, unless the next dose is almost due. If it is close, skip the missed dose and continue on schedule. Never give two doses at once to make up for a missed one.

Can I stop the medication once my cat feels better?

No. Stopping early can let surviving bacteria rebound and can breed resistance. Finish the full course your veterinarian prescribed, and call the clinic if you have concerns before the end date.

Does chloramphenicol interact with flea or tick products?

Possibly. Some parasite preventives are absorbed slowly and stay in the body for weeks, which can affect how other drugs are handled [3]. Tell your veterinarian about every preventive and supplement your cat receives so interactions can be checked.

Are antibiotics always needed after eye surgery in cats?

Not always. A recent observational study of eyelid and third eyelid surgeries in dogs and cats found that most animals did well without routine prophylactic antibiotics, with antibiotics reserved for specific clinical criteria [4]. This supports the broader push to use antibiotics only when there is a clear reason [5].

References

Retrospective description of the clinical use of chloramphenicol in client-owned cats: 12 cases (2015-2023). Journal of feline medicine and surgery, 2024.
Cats and Antibiotics. Pet Poison Helpline.
Pharmacokinetics, Absolute Bioavailability, and Nonlinear Topical Absorption of a Fluralaner-Moxidectin Spot-On Formulation in Cats. Veterinary sciences, 2026.
Reassessing Antibiotic Use in Canine and Feline Eyelid and Third Eyelid Surgeries: An Observational Study Supporting Selective Prophylaxis. Veterinary ophthalmology, 2026.
EXPRESS: Factors associated with antimicrobial drug prescription in cats receiving outpatient care at a veterinary teaching hospital. Journal of feline medicine and surgery, 2026.