Cat Conjunctivitis: Eye Infection Signs, Causes, and When to See a Vet

Red, watery, or crusty eyes are among the most common reasons cat owners call their vet — and in 2026, conjunctivitis remains the leading cause of eye problems in domestic cats. While a mild case may clear up with supportive care, many require veterinary treatment to avoid complications. Here's what every cat owner should know.

What Is Conjunctivitis in Cats?

Conjunctivitis is inflammation of the conjunctiva — the thin, pink membrane that lines the inner eyelids and the white part of the eyeball. When irritated or infected, this membrane becomes red, swollen, and may produce discharge ranging from clear and watery to thick and yellow-green.

According to Cornell's Feline Health Center, conjunctivitis is one of the most frequently diagnosed feline conditions, and it is often associated with upper respiratory infections.

Causes of Cat Conjunctivitis

Viral Infections (Most Common)

Feline herpesvirus (FHV-1) is the most frequent cause of conjunctivitis in cats, responsible for the majority of cases. Most cats are exposed to herpesvirus at some point in their lives — typically through contact with other cats — and the virus can cause recurrent flare-ups, especially during stress. Feline calicivirus can also cause eye inflammation as part of a broader respiratory infection.

Bacterial Infections

Chlamydophila felis is a common bacterial cause, especially in young cats and multi-cat households. It typically causes a persistent, one-sided discharge that may spread to both eyes. Mycoplasma is another bacterial culprit, particularly in kittens.

Allergies and Irritants

Dust, smoke, cleaning products, and pollen can cause non-infectious conjunctivitis. This type tends to affect both eyes equally and may improve when the irritant is removed.

Foreign Bodies

A piece of debris, grass seed, or even a fine hair lodged under the eyelid can trigger acute, one-sided conjunctivitis with tearing and pawing at the face.

Signs of Conjunctivitis in Cats

• Red or pink inner eyelid tissue — the "whites" of the eye may appear inflamed
• Eye discharge — ranging from clear and watery to thick yellow or green (learn more about cat eye discharge colors)
• Squinting or keeping one eye partially closed (blepharospasm)
• Pawing at the eye or rubbing the face on carpet
• Crusting or matting of fur around the eye
• One eye or both eyes affected — one-sided is often bacterial; both eyes suggests viral or allergic

When to Worry — Emergency Signs

See a vet urgently if your cat shows:

• Rapid swelling of the eye or surrounding area
• Cloudiness of the cornea (the clear dome over the pupil) — suggests ulceration
• Eye is bulging or sunken
• Third eyelid (a pink/white membrane) is visible and covering part of the eye
• Complete closure of one eye combined with significant pain
• Signs of upper respiratory infection — sneezing, nasal discharge, loss of appetite (cat upper respiratory infection can escalate quickly in kittens)

Corneal ulcers in cats are a serious complication of untreated herpesvirus conjunctivitis and can lead to permanent vision loss if not treated promptly.

What to Do at Home

1. Gently clean discharge from the eye using a damp, clean cloth — wipe from the inner corner outward
2. Separate affected cats from others in a multi-cat home to reduce transmission risk
3. Reduce stress — herpesvirus flare-ups are often triggered by stress, so keeping your cat's environment calm can help
4. Do not use human eye drops — many OTC products contain ingredients toxic or irritating to cats
5. Monitor closely — if symptoms worsen or don't improve within 24–48 hours, book a vet appointment

Treatment Options

Your vet will examine the eye and may stain it to check for corneal ulcers. Treatment depends on the cause:

• Viral (herpesvirus): Topical antiviral drops (e.g., idoxuridine), L-lysine supplementation to support immune function, and supportive care
• Bacterial: Topical antibiotic ointments such as tetracycline or tobramycin
• Allergic: Antihistamines or steroids (only after ruling out infection/ulcers — steroids worsen herpesvirus)

How Voyage Can Help

Not sure if your cat's red eye is an emergency or something that can wait until morning? Voyage AI Vet gives you an instant, informed assessment based on your cat's specific symptoms — starting at $4.99/month. No appointment needed. It's available at 3 AM when you're staring at a goopy eye and wondering what to do next.

Frequently Asked Questions

Q: Can cat conjunctivitis clear up on its own? A: Mild, non-infectious cases sometimes resolve with supportive care. However, viral and bacterial conjunctivitis typically require treatment, and untreated cases risk spreading to the other eye or causing corneal damage.

Q: Is cat conjunctivitis contagious to humans? A: Feline herpesvirus does not infect humans. However, Chlamydophila felis can rarely cause mild eye irritation in immunocompromised people. Basic hygiene — washing hands after handling your cat — is sufficient in most households.

Q: My cat has had recurring eye infections — why? A: Recurrent conjunctivitis in cats is often due to feline herpesvirus, which lies dormant and reactivates during stress or illness. Your vet may recommend L-lysine supplementation and stress management as part of ongoing management.

Q: Can I use saline drops for my cat's eye? A: Plain saline (not contact lens solution) can safely flush out mild discharge. However, this doesn't treat an underlying infection — if symptoms persist beyond a day, see a vet.

This article is for informational purposes only and is not a substitute for professional veterinary advice. Consult your veterinarian for proper diagnosis and treatment.