Not all eye discharge means something is wrong. A small amount of clear or rust-brown crust at the inner corner of your cat’s eye is usually just dried tears — harmless and easy to wipe away. Yellow or green discharge, a weeping eye that won’t quit, or a cat squinting and pawing at their face is a different story. Here’s how to tell which is which.
What Normal Eye Discharge Looks Like
Healthy cats produce a small amount of eye discharge, particularly after sleeping. These are the types that don’t require a vet visit:
- Clear or slightly watery discharge: Normal tear drainage, common in all cats
- Rust-brown or reddish-brown crust at the inner corner: Dried tears oxidised by air. Looks alarming, usually harmless
- A small amount of morning crust: The feline equivalent of “sleep” — normal
Flat-faced (brachycephalic) cats — Persians, Himalayans, Exotic Shorthairs — tend to produce significantly more discharge because their skull structure alters tear drainage. The tears overflow down the face rather than draining normally through the nasolacrimal duct. This is called epiphora, and it’s structural rather than a disease, though the wet fur below the eye can become irritated if not cleaned regularly.
Types of Discharge That Warrant a Vet Visit
These aren’t things to monitor and wait on:
Yellow or green discharge is the clearest warning sign. Opaque, coloured discharge almost always indicates bacterial involvement — either a primary infection or bacterial secondary infection following a virus. Upper respiratory infections are the most common cause in cats.
White or cloudy discharge can point to corneal injury, uveitis (inflammation inside the eye), or early-stage glaucoma. These can deteriorate quickly and need prompt evaluation.
One eye vs. both: Bilateral discharge (both eyes simultaneously) usually suggests a systemic cause — infection, allergy, or illness. One eye more affected than the other points toward a local problem on that side, such as injury, a blocked tear duct, or a foreign body.
Persistent watering beyond morning crust: Constant tear overflow during waking hours, especially if accompanied by puffiness or apparent discomfort, isn’t normal.
Common Causes of Eye Discharge in Cats
Feline Upper Respiratory Infections
The single most common cause of eye discharge in cats, particularly in kittens, recently adopted cats, or cats who’ve been in a shelter environment. Feline herpesvirus type 1 (FHV-1) and feline calicivirus are the primary viral culprits. Both cause conjunctivitis as a core symptom, alongside sneezing and nasal discharge.
According to the American Association of Feline Practitioners (AAFP), FHV-1 is estimated to infect the majority of cats at some point in their lives. Many become lifelong carriers with no visible symptoms — until stress triggers a flare. This is why a cat who’s otherwise seemed perfectly healthy can suddenly develop weepy eyes after a move, a new pet, or a bout of illness.
Discharge from herpesvirus starts watery and can turn mucoid or yellowish once secondary bacterial infection takes hold. Keeping your cat’s core vaccinations current offers protection against calicivirus and reduces severity of herpesvirus infections.
Conjunctivitis
Inflammation of the conjunctiva — the thin membrane lining the eyelids and covering the white of the eye — is one of the most frequently diagnosed eye conditions in cats. It can result from viral infection, bacterial infection (notably Chlamydophila felis and Mycoplasma species), environmental irritants, or foreign material in the eye. Discharge ranges from watery to thick and coloured, depending on cause.
Chlamydophila felis is worth knowing by name because it typically begins as one-sided conjunctivitis before spreading to the other eye. Vets often test for it in cats who haven’t responded to standard treatment.
Blocked Nasolacrimal Ducts
Tears drain from the eye through tiny ducts that empty into the nasal cavity. When these are obstructed — from chronic inflammation, scar tissue, or congenital narrowing — tears overflow down the face instead. You’ll see constantly wet fur below the inner corner of the eye, sometimes stained reddish-brown. Brachycephalic breeds are disproportionately affected.
A vet can confirm blockage by flushing the duct under light sedation. In some cases it can be cleared; in others, ongoing management is the approach.
Corneal Scratch or Ulcer
The cornea is vulnerable to injury, especially in cats who play rough or have outdoor access. Any scratch on the corneal surface causes tearing and discharge as the eye mounts its healing response. Squinting, holding the eye partially closed, or sudden onset of watering after a play session are the typical signs.
Corneal ulcers need vet care. The cornea is thin — untreated injuries can deepen and cause permanent damage. A vet will use fluorescein dye (a safe stain that highlights damaged areas) to assess the extent of any injury.
Allergies
Environmental allergies in cats can manifest as bilateral watery eye discharge, typically alongside sneezing. Less common than in dogs, but not rare. Seasonal patterns and absence of other illness signs can suggest allergic cause, but a vet should rule out infection before landing on allergy as a diagnosis.
How to Clean Your Cat’s Eyes Safely
For routine maintenance — particularly in flat-faced breeds — use a damp cotton pad or gauze to gently wipe dried crust from the inner eye corner. Always wipe away from the eye, not toward it. Use a fresh pad for each eye to avoid spreading anything from one side to the other.
Avoid loose-fibre cotton wool that can shed into the eye. Don’t use contact lens solution, hydrogen peroxide, or anything not specifically labelled as eye-safe for cats. Sterile saline or a veterinary eye wash is appropriate for gentle cleaning; plain water works in a pinch.
If your cat resists handling around the eyes, if the area looks swollen, or if cleaning seems to cause pain — stop and see a vet rather than pushing through.
When to See a Vet
Don’t wait if:
- Discharge is yellow, green, or white
- Your cat is squinting, pawing at the eye, or keeping it half-closed
- The eye looks cloudy, hazy, or bloodshot
- There’s visible swelling around the eye or eyelids
- Discharge is accompanied by sneezing, nasal discharge, or lethargy
- A kitten has eye discharge — kittens are more vulnerable to herpesvirus complications and secondary infections
- The discharge hasn’t cleared within 24–48 hours
Eye conditions can progress faster than you’d expect. If your cat is also being managed for conditions like chronic kidney disease or hyperthyroidism, watch for eye changes as potential secondary symptoms — compromised immune function can make cats more susceptible to recurrent infections.
When in doubt, a vet visit for an eye concern is never an overreaction. Eyes are worth treating with urgency.