Why are my cat's eyes red? Common causes and when to see a vet
Redness in a cat's eyes is usually caused by something mild and short-lived, such as dust, a scratch from play, or minor irritation, and often settles on its own within a day or two. It's worth seeing a vet promptly if the redness comes with swelling, discharge, squinting, or if your cat is pawing at the eye repeatedly, since some causes need treatment quickly to avoid lasting damage.
Usually not urgent
This is common and often manageable at home — but see a vet if it persists, gets worse, or comes with other changes.
The short answer
Red eyes in cats are a sign, not a specific condition, and the causes range from trivial to genuinely urgent. Mild redness with no other symptoms, in a cat who is otherwise bright, eating and behaving normally, is often something minor that clears up on its own within a day or so.
The exception is anything sudden and severe, or redness paired with other signs — swelling, closed or partly closed eyes, discharge, or a cat pawing at their face repeatedly. Those combinations are worth a same-day call to your vet rather than a wait-and-see approach.
Common causes of mild redness
Minor irritation is the most common cause — dust, pollen, a draught, or something as simple as a scratch during rough play with another cat or a bit of rough grass. This kind of redness tends to affect one eye more than the other, comes on suddenly, and usually settles within a day or two without other symptoms.
Allergies can also cause redness, sometimes alongside sneezing or a slightly runny nose, and tend to affect both eyes evenly rather than just one. If the redness follows a predictable pattern — worse at certain times of year, or after being somewhere specific — that pattern is worth mentioning to your vet.
A cat's third eyelid, the thin membrane in the inner corner of the eye, can also become slightly visible and reddened when a cat is generally under the weather with something unrelated to the eye itself, such as an upset stomach. It's a useful general sign of feeling off rather than a specific eye problem in its own right.
Causes that need a vet more promptly
Conjunctivitis — inflammation of the pink tissue around the eye — is common in cats and can be caused by infection, irritation or an underlying viral illness such as cat flu. It often causes more obvious redness and discharge than simple irritation, and while it isn't usually an emergency, it's worth having checked rather than left to run its course.
A scratch or injury to the surface of the eye can look like simple redness at first but cause a cat to squint, keep the eye closed, or paw at their face, and can worsen quickly without treatment. Anything suggesting pain — squinting, avoiding light, or a change in behaviour around the eye — is worth a same-day vet visit rather than waiting to see if it settles.
Raised pressure inside the eye is rarer but more serious, and can cause redness alongside a cloudy or enlarged-looking eye, or obvious discomfort. This is one of the genuine emergencies on this list, because delay risks permanent sight loss in the affected eye.
When to see a vet
Book a routine appointment if the redness is mild, affects one eye, and your cat is otherwise behaving normally, but hasn't cleared up within a day or two. Book the same day, or seek an emergency vet if your own practice is closed, if you see swelling, thick discharge, squinting, a cloudy or enlarged-looking eye, or your cat pawing at their face repeatedly.
This page describes what's commonly seen and when to get it checked — it's general information, not a diagnosis, and it can't replace an examination by a vet who can actually look at your cat's eye. If you're at all worried, that examination is the next step, not more reading.
What can help at home while you wait to be seen
Gently wiping away any discharge with a clean, damp cotton pad, wiped away from the eye rather than towards it, can keep your cat more comfortable while you arrange a vet visit. Use a fresh pad for each eye if both are affected, to avoid spreading anything from one eye to the other.
Beyond that, avoid putting anything into the eye yourself — no human eye drops, no home remedies — since the wrong product can make some causes worse, and a vet needs to see the eye in its natural state to assess it properly.
What can help
Things we stock that owners commonly use alongside a vet’s advice — not a substitute for it.
Leucillin Antiseptic Skincare Spray for Cats & Dogs
A versatile, alcohol-free antiseptic spray that cleans, soothes, and helps protect your pet's skin from bacteria, viruses, and fungi.
From£7.99
Absorbent Cotton Gauze Swabs for Pets – Pack of 100
Highly absorbent, low-lint cotton gauze swabs produced in clean conditions — a practical first-aid essential available in three size and ply combinations.
From£4.49
3M Synthetic Under Bandage Padding for Pets
A soft, breathable non-woven polyester padding layer designed to protect and cushion beneath bandages on dogs and cats.
From£9.49
Little Friends Trimmed Dried Cuttlefish Bones
Trimmed dried cuttlefish bones for birds, reptiles and small pets, a natural calcium source
£9.99
Common questions
- Can I put human eye drops in my cat's eyes?
- No, this isn't a good idea. Products made for people aren't formulated or tested for cats, and using the wrong one can worsen some of the causes of redness rather than help. If your cat's eye needs treating, your vet will prescribe something appropriate for the actual cause.
- Will my cat's red eye clear up on its own?
- Mild redness from minor irritation often does settle within a day or two on its own. If it hasn't improved by then, is getting worse, or comes with any other symptom like discharge or squinting, it's worth having it checked rather than continuing to wait.
- Is one red eye more serious than two?
- Not necessarily, but the pattern can be a useful clue. A single red eye is more often caused by a localised issue like a scratch or minor irritation, while both eyes being affected points more towards an allergy or a wider illness. Either pattern is worth a vet's opinion if it doesn't settle quickly.
- Can kittens get red eyes more easily than adult cats?
- Kittens are more prone to eye infections linked to cat flu and other viral illnesses circulating in young, unvaccinated cats, and their eyes can be more sensitive generally. Any redness in a kitten is worth checking with a vet sooner rather than later, given how quickly a young cat's condition can change.
- My cat's third eyelid is showing — is that the same as red eyes?
- Not exactly. A visible third eyelid, especially with some redness, often signals a cat is generally unwell with something unrelated to the eye, such as an upset stomach, rather than an eye-specific problem. It's still worth a vet visit to work out what's actually going on.
Related
Sources
Written against guidance published by UK veterinary and welfare organisations. Always confirm specifics with your own vet.
Written by Matt Garnett, who runs Giddy Pets and is a lifelong pet owner — not a vet. This is general information, not veterinary advice, and it cannot replace an examination by the vet who knows your animal. How we write these guides.