Quick Answer: Cat eye discharge is common and ranges from normal (small brown/black crust in the corner) to a sign of illness (yellow or green pus, excessive watering, squinting, or cloudiness). The most common causes are upper respiratory infections, feline herpesvirus, conjunctivitis, and allergies. Yellow-green discharge always requires a veterinary visit.
This guide is for informational purposes. Always consult a veterinarian for eye problems, which can deteriorate quickly in cats.
In This Guide:
Normal vs. Abnormal Cat Eye Discharge
| Discharge Type | Normal? | Likely Cause | Action |
|---|---|---|---|
| Tiny dark crust in corner | Normal | Dried normal secretions | Wipe gently, no concern |
| Clear watery discharge | Usually normal or mild irritation | Dust, wind, early allergy, herpes flare | Monitor; vet if persists 48h |
| Reddish-brown staining | Common (cosmetic) | Tear porphyrins, blocked duct | Daily cleaning; vet if sudden |
| White/grey mucus | Concerning | Dry eye, herpesvirus, early conjunctivitis | Vet visit recommended |
| Yellow or green pus | Always concerning | Bacterial conjunctivitis, URI, chlamydophila | Vet visit promptly |
| Discharge + squinting | Urgent | Corneal ulcer (herpes), foreign body | Same-day vet visit |
| One eye closed/swollen shut | Emergency | Severe infection, trauma, abscess | Emergency vet immediately |
Source: Cornell Feline Health Center; American Association of Feline Practitioners ophthalmology guidelines
Causes of Cat Eye Discharge
- Feline Herpesvirus (FHV-1): The most common cause of eye discharge in cats. Herpesvirus causes conjunctivitis, watery to mucoid discharge, and in severe cases, corneal ulcers. Many cats carry the virus latently and experience flare-ups during stress. See our guide on cat cold symptoms for more on feline URI
- Bacterial Conjunctivitis: Often secondary to viral infection. Chlamydophila felis is a primary bacterial cause of feline conjunctivitis, producing yellow-green discharge and eye swelling. Responds well to topical antibiotics
- Feline Calicivirus (FCV): Along with causing mouth ulcers, calicivirus can cause mild to moderate eye discharge as part of upper respiratory infection
- Allergies: Environmental allergens cause bilateral (both eyes) clear watery discharge, often with sneezing and cat anxiety
- Dry Eye (KCS): Less common in cats than dogs but occurs — especially following herpesvirus-related damage to tear glands. Produces thick, ropy discharge
- Entropion: Eyelid rolling inward, causing lashes to irritate the cornea — more common in Persian and Himalayan cats
- Corneal Ulcer: Often caused by herpesvirus or trauma — presents as acute squinting, tearing, light sensitivity. A veterinary emergency
How to Clean Your Cat’s Eyes
- Use a cotton ball or soft cloth dampened with sterile saline or clean warm water
- Wipe from the inner corner of the eye (near the nose) outward toward the ear
- Use a fresh cotton ball for each eye to prevent cross-contamination
- For crusted discharge, hold the damp cloth gently against the closed eye for 30 seconds to soften before wiping
- Clean 1–2 times daily when discharge is present
- Never use human eye drops, hydrogen peroxide, or tea tree oil near your cat’s eyes
- If a cat’s eye is swollen shut, do not force it open — let a veterinarian examine it
Veterinary Treatment Options
Treatment depends on the underlying cause:
- Viral (herpesvirus): Topical antiviral drops (idoxuridine, cidofovir), oral famciclovir for severe cases, L-lysine supplementation (controversial but commonly used)
- Bacterial conjunctivitis: Topical antibiotic eye drops or ointment (oxytetracycline, chloramphenicol, azithromycin for Chlamydophila)
- Dry eye: Cyclosporine or tacrolimus eye drops to stimulate tear production; frequent artificial tear application
- Corneal ulcer: Topical antibiotics + antiviral drops; pain management; e-collar to prevent pawing; in severe cases, surgical intervention
- Allergies: Antihistamines, avoiding triggers, air purifiers; in chronic cases, immunotherapy
Prevention
- Keep vaccinations current — the FVRCP vaccine protects against herpesvirus and calicivirus, the main causes of infectious eye discharge. See our guide on cat vaccination schedules
- Minimize stress — herpesvirus reactivates under stress; stable home routines reduce flare-ups
- Keep eye area clean and hair trimmed for flat-faced breeds
- For multi-cat households, quarantine cats with active eye discharge — conjunctivitis is contagious between cats
- Schedule regular veterinary wellness exams to catch eye issues early. Find a vet near you
Frequently Asked Questions
What causes cat eye discharge?
The most common causes of cat eye discharge are feline herpesvirus (FHV-1) and bacterial conjunctivitis — both often occurring together during upper respiratory infections. Other causes include feline calicivirus, allergies, dry eye, blocked tear ducts, corneal injuries, or structural issues in flat-faced breeds like Persians. Small amounts of dark crust in the corner are normal; yellow-green discharge always requires a vet visit.
Is cat eye discharge contagious to humans?
The viruses causing most cat eye discharge (feline herpesvirus, calicivirus) are species-specific and cannot infect humans. However, Chlamydophila felis — a bacterial cause of feline conjunctivitis — can rarely cause mild conjunctivitis in humans through direct eye contact with infected cat secretions. Wash hands thoroughly after handling a cat with eye discharge, especially before touching your own eyes. This is a very rare occurrence.
Can I use human eye drops on my cat?
No — never use human eye drops in your cat’s eyes without specific veterinary guidance. Most human eye drops contain preservatives and compounds that can be toxic to cats. This includes decongestant eye drops, which can cause serious side effects. The only safe option is unpreserved sterile saline for cleaning. Always use veterinary-prescribed eye medications for treatment.
Why does my cat have brown discharge under the eyes?
Brown or reddish-brown staining (epiphora) under cat eyes is caused by porphyrin pigments in tears oxidizing on contact with air and fur. It is especially common in flat-faced breeds like Persians and Himalayans. While usually cosmetic, worsening staining or sudden onset can indicate a blocked tear duct, herpesvirus flare-up, or other eye irritation. Daily cleaning and a vet check if it worsens is the appropriate response.
When should I take my cat to the vet for eye discharge?
See a vet promptly if the discharge is yellow or green, if your cat is squinting or keeping one eye closed, if there is swelling around the eye, if the eye appears cloudy or the pupil size differs between eyes, if the discharge started suddenly rather than gradually, or if your cat is pawing at the affected eye. Kittens with eye discharge should always be seen promptly, as infections can cause permanent damage to developing eyes.
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