Your cat shows up for breakfast, meowing and rubbing against you, as always. But when they look up, you immediately notice a problem. Your cat’s eyes are red and irritated, with a greenish-yellow discharge coming from the corners.

What is happening? How much of an emergency is this?

This is an extremely common scenario with cats. Here’s what you need to know about red eyes in cats, including other symptoms you may see and how it’s treated.

Types of Red Eye in Cats

There are a few things to check if you’re concerned there might be something wrong with your cat’s eyes.

First, is it one eye or both eyes?

An injury will usually affect only one eye, whereas bacterial and viral infections are more likely to affect both. Is your cat able to open their eye(s)? If not, this is a sign of a more serious problem.

Where is the redness?

  • Is it the tissue that’s red and swollen? Sometimes, the membranes around the eye (called the conjunctiva) can be so swollen you can’t even see the eye itself.

  • Is the inflammation on the whites of the eyes? This is where blood vessels run through the whites and make the eye look bloodshot.

  • Is there a “membrane” (called the third eyelid) covering the eye? This is a whitish structure that comes up from the nose side of the eye at an angle to help protect the eye when it’s sore. When it is raised, the eye can have an alarming appearance.

  • Does the entire eyeball look swollen? The more swollen and redder the eye is, the more pressing the concern.

Is there any discharge?

If so, what color is it? Bloody discharge can be a sign of a serious injury, while yellow or green is more common with infection. Thicker discharge is often seen if there is mucus buildup, whereas a thinner discharge often happens with excess tearing.

What to Do if Your Cat Has Red Eyes

“When in doubt, check it out” is the general rule with eyes. You don’t want to let a potentially serious eye problem go undiagnosed or have your cat lose their vision or possibly their eye. If you feel something is wrong with your cat’s eye, have it checked out as soon as possible.

Cats with significant redness, swelling, or discharge from the eye—and those that are unable to open their eyes—should be seen immediately on an emergency basis, as should cats that aren’t feeling well and have changes in their eyes.

If your cat can open their eyes, they seem to be feeling fine otherwise, and the signs are mild, the problem can likely wait up to 48 hours for an appointment. But when you aren’t sure, call your vet to ask for advice.

Causes of Red Eyes in Cats

Many conditions can affect cats’ eyes, some of which concern the eye itself (called the globe) and others that affect the tissue surrounding the eye. Problems affecting the globe are usually more serious than those affecting the tissue.


Perhaps the most common condition that causes red eyes in cats is conjunctivitis. This is inflammation of the tissue around the eye that may also affect the eye surface, called the cornea.

Viral infections are particularly common in cats and cause inflammation of the conjunctiva (sometimes with dramatic swelling), as well as discharge and squinting. Bacterial infections also cause similar signs. These types of conjunctivitis are not considered contagious to humans, although they can be contagious to other cats.


Another common reason cats develop red eyes is because of an injury. It only takes a small speck of dust, a swat from another cat, or a poke in the eye to injure the surface of the eye or the tissues around the eye. Injuries to the surface of the eye can be serious because the area does not have blood flow to it. This is why it is clear and transparent when it is healthy.

This area needs to be protected from infection until the body can grow blood vessels to the wound, bringing healing substances and immune defense against infection. Injuries should be treated by a veterinarian as soon as possible.

Less Common Causes

Other less common causes of red eyes include:

  • Allergies

  • Glaucoma

  • Household irritants like perfumes and candles

  • Hyphema, which is bleeding into the front of the eye

  • Infections

It usually takes some detective work to find the underlying cause of the problem.

How Vets Diagnose the Cause of Red Eyes in Cats

Many, if not most, cases of red eyes in cats can be diagnosed by a veterinarian by checking your cat’s health record, asking questions, conducting a physical exam, and doing a fluorescein stain test. In this test, a small amount of dye is placed on the surface of the eye to look for scratches or injuries to the cornea.

In more complicated cases, the veterinarian may need a tonometry test (this measures the pressures in the eye); a Schirmer tear test (looking at how well tears are being produced); blood work; and X-rays.

Just as each animal and each situation is unique, the tests recommended by your veterinarian will vary depending on the situation. In most cases, an exam and a fluorescein stain test will be needed.

Treatment for Red Eyes in Cats

Treatment will depend on the diagnosis. However, many cases of red eye are treated by first removing the discharge in the eye—which can often be done carefully with a moistened gauze—and keeping the face clean. Then, appropriate medications will be recommended.

Drops or ointments, which may contain anti-inflammatory as well as anti-infectious medications, are used for most cases of conjunctivitis. Injuries must also be carefully treated to ensure that infection doesn’t set in while medication to treat pain and inflammation is applied. Some cats may also benefit from oral medications, but for most pets, topical treatment is the mainstay.

Generally, within a week or so, the eye inflammation should be greatly reduced or gone with appropriate diagnosis and treatment.

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Sandra C. Mitchell, DVM, DABVP


Sandra C. Mitchell, DVM, DABVP


Sandra Mitchell is a 1995 graduate of the New York State College of Veterinary Medicine. Since graduation, she has worked in many fields...

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