Chloramphenicol Eye Drops and Ointment for Cats

Name: Chloramphenicol Eye Drops and Ointment for Cats
Creator: Dr. Zubair Khalid

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

Chloramphenicol for cats eyes is a prescription antibiotic that fights certain bacterial eye infections, most often conjunctivitis caused by Chlamydia felis. It comes as drops or ointment and only a veterinarian should decide whether your cat needs it. Giving it for the wrong eye problem, such as a viral infection or a corneal ulcer, can make things worse.

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

Quick Answer

Chloramphenicol eye preparations are prescription antibiotics used for bacterial conjunctivitis in cats, including infections caused by Chlamydia felis [1].
A corneal ulcer must be ruled out by your veterinarian before you use any eye medication, because some products can slow healing or cause harm.
Your veterinarian calculates the dose and schedule based on your cat's weight, the diagnosis, and the product form (drops or ointment).
Never use leftover chloramphenicol from a previous pet or a human prescription. The tube or bottle is not interchangeable between species or between eye conditions.
Watch for redness that worsens, squinting, cloudiness, or swelling around the eye. These are reasons to call your veterinarian the same day.

What Chloramphenicol Eye Preparations Are and When Vets Use Them

Chloramphenicol is an antibiotic that stops bacteria from making proteins they need to survive. In cats, the eye forms (drops and ointment) are used to treat bacterial conjunctivitis. The conjunctiva is the thin membrane that lines the eyelids and covers the white of the eye [2]. When bacteria infect that membrane, the eye becomes red, swollen, and often produces discharge.

The most common bacterial cause of conjunctivitis in cats is Chlamydia felis, sometimes called feline pneumonitis [1]. Despite the name, this bacterium rarely causes pneumonia. It mainly affects the eye and sometimes the nose [1]. Most affected cats are less than a year old [1].

Signs include clear or colored eye discharge, red and swollen conjunctivae in one or both eyes, nasal discharge, and sneezing [1]. These signs tend to be worst about 9 to 13 days after they start, then ease over 2 to 3 weeks [1]. Some cats keep showing signs for weeks even with treatment, and the infection can come back [1].

Chloramphenicol is not the only antibiotic used for cat eye infections. Your veterinarian may choose a different topical antibiotic depending on what they find during the exam. If you want to understand the broader treatment picture, see Cat Eye Conjunctivitis Treatment.

Drops or Ointment?

Both forms deliver the same drug to the eye surface. Drops are clear, easy to measure, and usually applied more often. Ointments stay on the eye longer but blur vision and can be greasier. Your veterinarian will pick the form based on the severity of the infection, how well you can medicate your cat, and how often the eye needs treatment.

How Chloramphenicol Works for Cat Eye Infections

Bacteria need proteins to build cell walls, copy themselves, and cause damage. Chloramphenicol blocks the bacterial ribosome, which is the cell structure that builds proteins. Without new proteins, the bacteria stop multiplying and die off. This makes chloramphenicol a bacteriostatic antibiotic, meaning it slows or stops bacterial growth instead of instantly killing every organism.

Because the drug acts on a bacterial structure that differs from mammalian cells, it can target the infection while mostly sparing your cat's own tissues. That said, chloramphenicol can still be absorbed through the eye surface and into the bloodstream, especially if the eye is inflamed or if the cat grooms the medication off and swallows it. That is one reason it stays prescription-only.

Chloramphenicol for cats conjunctivitis works best when the diagnosis is confirmed. Your veterinarian can take a smear from the conjunctiva and look for the organism under a microscope or send it to a lab [1]. Identifying the exact cause matters because viral infections, allergies, and foreign bodies can all look similar at home but need very different treatment.

Dosing Basics for Chloramphenicol for Cats Eyes

Your veterinarian decides the dose, the number of drops or the length of ointment ribbon, and how many times per day to treat. There is no safe at-home dose chart for this medication. The right amount depends on your cat's weight, the specific product concentration, the diagnosis, and whether one or both eyes are affected.

A retrospective study of 12 client-owned cats treated with chloramphenicol described an oral dose, not an eye dose, of 13.3 mg/kg given every 12 hours for a median of 14.5 days [3]. That number applies to the oral form used for complicated infections in that case series. It does not tell you how to dose eye drops or ointment, and you should not use it to calculate anything at home.

How to Apply Eye Medication

Wash your hands.
Gently hold your cat's head steady. You can wrap a towel around the body if your cat wiggles.
With one hand, lift the upper eyelid slightly to create a small pocket.
Squeeze one drop or a short ribbon of ointment into the pocket. Do not touch the tube tip to the eye.
Let your cat blink to spread the medication.
Reward with a treat or quiet praise.

If your cat fights eye drops, a calm, low-stress approach helps. For step-by-step tips, read How to Give Your Cat Eye Drops Without a Fight.

Missed Doses

If you miss a dose, give it when you remember unless it is almost time for the next one. Do not double up to catch up. Call your veterinarian if you miss more than one dose in a row, because skipped doses can let the infection rebound.

Finishing the Course

Give the full course your veterinarian prescribed, even if the eye looks normal after a few days. Stopping early can allow surviving bacteria to regrow and can lead to recurrence, which is already common with chlamydial infections [1].

Side Effects of Chloramphenicol for Cats Eyes

Most cats tolerate topical chloramphenicol well. The most common problems are local and mild. Serious reactions are uncommon but possible, especially if the medication is swallowed during grooming or if it is used on a damaged cornea.

Side effect	How common or serious	What to do
Mild stinging or burning right after application	Common, usually mild	Wait a minute. If it happens every time and your cat panics, call your veterinarian about switching products.
Increased redness or swelling of the conjunctiva	Uncommon, can be serious	Stop the medication and call your veterinarian the same day.
Squinting, pawing at the eye, or keeping the eye closed	Uncommon, can be serious	Stop the medication and call your veterinarian the same day. These signs can mean a corneal ulcer or a reaction.
Cloudiness of the cornea	Uncommon, serious	Call your veterinarian the same day. Do not wait to see if it clears.
Vomiting, drooling, or lethargy after grooming the eye	Uncommon, can be serious	Call your veterinarian or a poison control service right away.
Blood disorders from systemic absorption	Rare with eye use, serious	Report any unusual bruising, bleeding, or pale gums to your veterinarian immediately.

Chloramphenicol for cats eyes side effects are usually local, but because the drug can be absorbed, systemic effects are possible. If your cat has a known blood disorder or liver problem, tell your veterinarian before starting treatment.

Who Should Not Use Chloramphenicol Eye Preparations

Do not use chloramphenicol eye drops or ointment on a cat with a corneal ulcer unless your veterinarian has examined the eye and specifically recommended it. An ulcer is a break in the clear surface of the eye. Some eye medications can delay healing or cause further damage when the cornea is damaged. Your veterinarian may use a fluorescein stain to check for an ulcer before prescribing anything.

Do not use chloramphenicol in a cat that has had an allergic reaction to it or to related antibiotics. Do not use it in a cat with certain blood or bone marrow conditions without veterinary guidance.

Do not use chloramphenicol eye products meant for people or for dogs on your cat. The concentration, the preservatives, and the dosing schedule can differ.

Drug Interactions

Tell your veterinarian about every medication your cat takes, including other eye drops, oral antibiotics, and supplements. Chloramphenicol can interact with other drugs that affect the liver or bone marrow. Your veterinarian needs the full list to choose a safe treatment plan.

If your cat is already on another antibiotic for the same eye, do not stack the two unless your veterinarian says to. Using two antibiotics at once without guidance can increase irritation and may not improve the outcome.

Overdose and When to Call for Help

An overdose of eye medication is unlikely from a single extra drop. The bigger risk is your cat swallowing the medication while grooming. If your cat swallows a large amount of chloramphenicol eye product, or if you are not sure how much was swallowed, call your veterinarian or a pet poison control hotline right away. Have the product name, the concentration, and your cat's weight ready.

Signs that need urgent help include vomiting, drooling, weakness, collapse, pale gums, or trouble breathing. Do not wait for these to pass on their own.

Limitations and When to Contact a Veterinarian

Chloramphenicol eye preparations only treat certain bacterial infections. They do not treat viral conjunctivitis, allergies, foreign bodies, or corneal ulcers. Using the wrong medication can let the real problem get worse. If you are unsure what is causing your cat's eye problem, see What To Use For Conjunctivitis In Cats for background, then call your veterinarian.

Call your veterinarian the same day if:

The eye looks worse after 24 to 48 hours of treatment.
Your cat squints, paws at the eye, or holds the eye closed.
You see cloudiness, a white spot, or a change in eye color.
The discharge becomes thick, yellow, or green.
Your cat stops eating or seems lethargic.

Go to an emergency clinic now if:

The eye is bulging or bleeding.
Your cat suddenly cannot see or bumps into things.
There is a deep wound or a foreign object in the eye.
Your cat collapses, has trouble breathing, or has pale gums.

Schedule a routine recheck if the eye is improving but not fully normal by the end of the prescribed course. Recurrence is common with chlamydial infections, so a follow-up exam helps confirm the infection has cleared [1].

Every cat is different. Your veterinarian needs to examine your cat, check the cornea, and confirm the diagnosis before deciding whether chloramphenicol is the right choice.

Frequently Asked Questions

Can I use chloramphenicol eye drops on my cat without a prescription?

No. Chloramphenicol eye preparations are prescription medications, and a veterinarian needs to examine your cat first. Giving the wrong eye medication can worsen an ulcer or mask a more serious problem.

How long does it take for chloramphenicol to work on a cat eye infection?

Many cats improve within a few days, but chlamydial infections can take 2 to 3 weeks to fully settle and can last longer despite treatment [1]. Finish the entire course your veterinarian prescribes, even if the eye looks better sooner.

Is chloramphenicol safe for kittens?

Kittens can get chlamydial conjunctivitis, and most affected cats are under a year old [1]. Only your veterinarian can decide whether chloramphenicol is safe for your kitten based on age, weight, and overall health.

Can chloramphenicol eye ointment be used instead of drops?

Both forms contain the same drug, but they are applied differently and at different frequencies. Your veterinarian will choose the form that fits your cat's diagnosis and your ability to medicate the eye.

What should I do if my cat swallows chloramphenicol eye medication?

Call your veterinarian or a pet poison control hotline right away. Bring the product container so you can read the concentration and the amount your cat may have swallowed. Watch for vomiting, drooling, weakness, or pale gums and seek emergency care if any appear.

References

Chlamydial Conjunctivitis in Cats (Feline Pneumonitis) - Cat Owners. Merck Veterinary Manual.
Disorders of the Conjunctiva in Cats - Cat Owners. Merck Veterinary Manual.
Retrospective description of the clinical use of chloramphenicol in client-owned cats: 12 cases (2015-2023). Journal of feline medicine and surgery, 2024.