Cat Eye Discharge: Causes and When to See a Vet

By Dr. Zubair Khalid, DVM, MS, PhD · 2026-08-14

Key Takeaways

• Urgent veterinary intervention is critical for specific signs: Immediate emergency veterinary care is required for cats exhibiting a completely swollen shut eye, thick green or yellow pus, blood in the eye, cloudy or white eyeball appearance, vocalization or pawing at the eye, hiding behavior, or sudden apparent blindness, as these can indicate severe conditions like deep ulcers, glaucoma, or acute infections that risk rapid vision loss.
• Feline herpesvirus (FHV-1) is the most common etiology: This ubiquitous virus, which remains latent in the body, frequently causes recurrent flare-ups characterized by clear to slightly cloudy discharge, conjunctivitis (redness and swelling of the conjunctiva), and sometimes sneezing, necessitating veterinary prescription of antiviral medications to prevent corneal ulceration.
• Bacterial infections and blocked tear ducts require specific veterinary treatment: Thick, colored discharge often suggests a secondary bacterial infection requiring antibiotic eye drops or ointments, while clear, watery discharge with damp fur below the eye may indicate a blocked nasolacrimal duct, which can be resolved by veterinary flushing.
• Home care is limited to supportive comfort and observation: Gentle wiping of mild, clear discharge with a warm, damp cloth is appropriate for comfort, but it does not treat underlying infections or viral causes; any change in discharge color, increased discharge volume, or the onset of squinting necessitates prompt veterinary consultation.
• Veterinary diagnosis is essential for appropriate treatment: A veterinarian utilizes tools such as fluorescein staining to detect corneal ulcers, Schirmer tear tests to assess tear production, and potentially swabs for viral or bacterial culture, as human over-the-counter medications or home remedies are ineffective and potentially harmful.
• Preventative measures focus on stress reduction and environmental hygiene: For cats prone to FHV-1 flare-ups, minimizing stressors, maintaining consistent routines, ensuring a clean environment to reduce viral load, and supporting overall immune health through balanced nutrition are crucial for reducing outbreak frequency.

Your cat's eye discharge can range from a harmless morning crust to a sign of a serious problem. The most important thing to know is this: if your cat cannot open the eye, is showing signs of pain, or has suddenly lost vision, this is an emergency and you should go to an emergency veterinarian immediately. For most other cases, you have time to observe carefully and call your regular vet for advice. This guide will help you sort out what you are seeing and decide how quickly your cat needs help.

Eye discharge in cats is common. The causes vary from mild allergies to viral infections that need prescription treatment. Your job is not to diagnose the problem. Your job is to recognize the signs that mean your cat needs urgent care versus signs that can wait for a regular appointment. When in doubt, call your veterinarian. A quick phone call costs nothing and can save your cat from unnecessary suffering.

Is This an Emergency?

Use this table as your first guide. If your cat matches any sign in the top row, stop reading and go to an emergency vet now. Do not wait to see if it improves.

{
 "type": "triage",
 "title": "Urgency triage by severity of signs",
 "tiers": [
  {
   "tier": "danger",
   "label": "Go to emergency vet now",
   "signs": [
    "Eye is completely swollen shut, green or yellow thick pus pouring from the eye, blood in the eye, the eyeball looks cloudy or white, your cat is crying out or pawing at the eye, your cat is hiding and refusing to move, or your cat suddenly seems blind (bumping into furniture)"
   ],
   "action": [
    "Do not wait",
    "This can mean a deep ulcer, severe infection, or sudden glaucoma",
    "These conditions can cause permanent vision loss within hours"
   ]
  },
  {
   "tier": "warn",
   "label": "Book a same-day appointment",
   "signs": [
    "Eye is partially closed, discharge is yellow or green but the cat can still open the eye, the third eyelid (the pink membrane in the inner corner) is covering part of the eye, your cat is squinting but not crying, or discharge has been present for more than 24 hours without improving"
   ],
   "action": [
    "Call your regular vet when they open",
    "Most eye infections need prescription treatment",
    "Waiting more than a day can make the problem worse"
   ]
  },
  {
   "tier": "safe",
   "label": "Watch at home for 24 to 48 hours",
   "signs": [
    "Clear, watery discharge with no squinting, no redness, no swelling, and your cat is eating, playing, and acting normally",
    "A small amount of dried crust in the inner corner after sleep is also normal"
   ],
   "action": [
    "Wipe the eye gently with a warm, damp cloth",
    "Use a fresh cloth for each eye",
    "If the discharge changes color, thickens, or your cat starts squinting, move up to the same-day category"
   ]
  }
 ]
}

What Is Most Likely Going On: Feline Herpesvirus

The most common cause of eye discharge in cats is feline herpesvirus, often called FHV-1. This is a virus that most cats are exposed to at some point. It is not the same as the human cold sore virus, but it behaves in a similar way. Once a cat gets the virus, it stays in the body for life. Stress, illness, or a change in routine can trigger a flare-up.

During a flare-up, you may see clear or slightly cloudy discharge, squinting, redness in the white of the eye, and sometimes sneezing. The virus can also cause conjunctivitis, which is inflammation of the pink tissue lining the eyelids and covering the front of the eye. This tissue is called the conjunctiva. When it is inflamed, the eye looks red and swollen and may produce more discharge than usual.

Most herpesvirus flare-ups are not emergencies, but they do need veterinary attention. Your vet can prescribe antiviral eye drops or oral medication to shorten the flare-up and protect the cornea, which is the clear front surface of the eye. Without treatment, a herpesvirus flare-up can lead to corneal ulcers, which are open sores on the eye surface. These ulcers are painful and can threaten vision.

What Else It Could Be: Bacterial Infection and Blocked Tear Ducts

Bacterial infections are another common cause of eye discharge. These often develop after a viral infection has weakened the eye's natural defenses. The discharge from a bacterial infection is typically thick, yellow, or green, and it may crust over the eyelids. Your cat may squint because the eye feels gritty and sore. Bacterial infections require prescription antibiotic eye drops or ointment. You cannot treat these with over-the-counter human eye drops, and giving the wrong medication can make the problem worse.

A blocked tear duct is a different issue. Tears normally drain from the eye through tiny tubes into the nose. If these tubes become blocked, tears spill over the eyelid and run down the face. The discharge is clear and watery, and the fur below the eye may stay damp. This is rarely an emergency, but it can lead to skin irritation and infection over time. Your vet can flush the duct to clear the blockage.

What Else It Could Be: Allergies and Irritants

Allergies can cause clear, watery eye discharge in cats. Dust, pollen, mold, or even certain cat litters can trigger this response. The eyes may look slightly red but should not be swollen shut. Your cat may also sneeze or have itchy skin. If you recently changed your cat's litter, switched to a new cleaning product, or brought new plants into the house, that could be the trigger.

Irritants work the same way. Smoke, perfume, aerosol sprays, and dusty environments can make a cat's eyes water. Removing the irritant often resolves the problem within a day or two. If the discharge continues beyond 48 hours, or if it changes from clear to colored, call your vet.

When Home Care Is Not Enough

You can wipe away mild discharge with a warm, damp cloth, but home care cannot treat an infection, a virus, or a blocked duct. These conditions need a diagnosis from a veterinarian who can examine the eye with a special light and stain. The stain, called fluorescein, reveals scratches or ulcers on the cornea that you cannot see with the naked eye.

Remote or online veterinary care has limits. According to the American Veterinary Medical Association, a veterinarian must have an established relationship with you and your pet to diagnose conditions and prescribe medication in most cases. This means your vet needs to examine your cat in person at least once before they can safely treat an eye problem. The FDA also notes that prescribing medications through telemedicine requires a valid veterinarian-client-patient relationship. Eye problems are especially risky to treat remotely because many conditions look similar but require very different treatments. A clear discharge can be allergies or a viral flare-up. A green discharge can be a bacterial infection or a foreign object stuck under the eyelid. Only an in-person exam can tell the difference.

If your cat's eye discharge does not improve within 48 hours of home wiping, or if any sign from the emergency table appears, seek in-person veterinary care. Your cat's vision depends on getting the right treatment quickly.

What You Can Safely Do at Home Right Now

If your cat has mild discharge, no breathing trouble, and is eating, drinking, and acting normally, gentle home care can help while you decide whether to call a vet. The goal is comfort and cleanliness, not treatment.

Warm a clean, soft cloth or cotton pad with water that feels barely warm on your inner wrist. Wipe from the inner corner of the eye outward, using a fresh part of the cloth for each eye. Do this once or twice daily. Never scrub. Never use the same cloth on both eyes if one eye looks worse than the other.

Do not use any human eye drops, contact lens solution, saline rinse, tea, or herbal preparations. These can sting, disrupt the natural tear film, or contain preservatives that damage the cornea, the clear front surface of the eye. Do not touch the eyeball itself. Do not try to open the eye if your cat is squinting hard or resisting. A cat in pain may scratch, and a scratch to the eye is an emergency.

Keep your cat indoors. Limit dust, smoke, scented candles, and strong cleaning products. Reduce stress where you can, because stress triggers flare-ups of feline herpesvirus, the most common cause of cat eye discharge. A quiet room, familiar bedding, and a consistent routine help.

Cat Eye Discharge Color Comparison Table

This table helps you describe what you see. It does not replace a vet's diagnosis.

Home Cleaning Guide

• Wash your hands before and after touching your cat's face.
• Use a fresh cloth or pad for each cleaning session.
• Wipe outward, away from the nose, to avoid spreading discharge into the other eye.
• If crusts are stuck to the fur, hold the warm cloth over the area for 30 seconds to soften them, then wipe gently.
• Do not pull crusts off. Let them release on their own.
• Watch for changes. If discharge increases, changes color, or the eye becomes more swollen, stop home care and contact a vet.

What to Write Down Before You Call a Vet

A few minutes of observation makes the call more useful. Write down:

• When the discharge started and whether it has changed.
• Which eye is affected, or both.
• The color and thickness of the discharge.
• How often your cat blinks or squints.
• Whether your cat is pawing at the eye or rubbing its face on furniture.
• Whether your cat is eating, drinking, and using the litter box normally.
• Any sneezing, nasal discharge, or reduced appetite.
• Whether your cat has had this before, and if so, what helped.

Also measure two things at home. Count your cat's breathing rate while it is resting and calm. A normal rate is roughly 20 to 30 breaths per minute. Count for 30 seconds and multiply by two. If it is over 40, or if breathing looks labored, that is an emergency. Check your cat's gum color. Healthy gums are pink. Pale, white, blue, or gray gums are an emergency.

What a Veterinary Visit Usually Involves

The vet will ask about the history you wrote down. They will examine both eyes with a bright light, often with a magnifying lens. They may use a fluorescein stain, an orange dye that glows under blue light, to check for scratches or ulcers on the cornea. This is quick and painless. They may also check tear production with a small paper strip placed under the eyelid for one minute.

Depending on what they find, the vet may recommend bloodwork, especially if the cat is young, old, or unwell. They may take a swab from the eye to test for herpesvirus or bacteria. Most cases are diagnosed by examination and history alone.

Treatment depends on the cause. Herpesvirus is often managed with antiviral medication, supportive care, and sometimes an amino acid supplement called L-lysine, though evidence for its benefit is mixed. Bacterial infections may need antibiotic eye ointment or drops. The dose and frequency must come from your treating veterinarian. Giving the wrong drug or dose can make things worse, and some eye medications are dangerous if used incorrectly.

Costs vary widely by region and clinic. A basic exam with stain runs roughly $50 to $150. Adding tests, medications, or follow-up visits can raise that to $200 to $500 or more. These are general ranges only, not quotes. Ask your clinic for an estimate before treatment begins.

When an Online Vet Can Help, and When It Cannot

Some situations in this article require hands-on care and must not be handled remotely. If your cat has difficulty breathing, pale gums, collapse, a swollen or bulging eye, a visible wound, or sudden blindness, go to an emergency clinic now. If the eye is painful, with constant squinting, or if the discharge is bloody, do not rely on a video call. These signs can indicate a serious ulcer, glaucoma, or other damage that needs in-person examination and testing. Remote care cannot place a stain on the eye, measure eye pressure, or examine the cornea properly.

A remote consultation is genuinely useful for early or mild presentations. If your cat has a small amount of clear discharge, is eating and playing normally, and you are unsure whether a visit is needed, an online vet can help you decide. It is also useful for a recheck on a known problem, a question about whether a sign warrants a visit, a medication side effect question, or a follow-up on a chronic condition like herpesvirus.

A remote vet can take a history, look at visible signs on video, advise, and in many states prescribe. But they cannot palpate the abdomen, listen to the chest, take a temperature, run bloodwork, or image anything. Prescribing rules differ by state, and a veterinarian may require an in-person examination first. The American Veterinary Medical Association explains what telehealth can legally and safely cover, and the FDA outlines prescribing requirements for veterinary telemedicine. Use remote care as a triage tool, not a substitute for hands-on diagnosis when the cause is unclear.

Common Mistakes Owners Make With Cat Eye Discharge

Many well-meaning owners make the same errors when their cat has eye discharge. Knowing these can save you time, money, and your cat's eyesight.

Mistake: Waiting to see if it clears up on its own. Eye problems can worsen quickly. A mild discharge can become a deep ulcer or permanent scarring within 48 hours. If your cat is squinting, pawing at the eye, or the discharge is yellow or green, do not wait. Call your veterinarian the same day.

Mistake: Using leftover human eye drops or ointments. Human medications are not safe for cats. Some contain ingredients that are toxic to felines, and the dose is never correct. Never give any human eye product to your cat. Only a veterinarian can determine the right medication and dose for your pet.

Mistake: Cleaning the eye too aggressively. Rubbing or scrubbing can damage the delicate surface of the eye. Use a soft, damp cloth and wipe gently from the inner corner outward. Use a fresh area of the cloth for each pass. Never touch the eyeball itself.

Mistake: Assuming it is just allergies. Allergies are possible, but they are not the most common cause in cats. Feline herpesvirus is far more frequent, and it needs specific management. Guessing the cause delays proper treatment.

Mistake: Stopping medication early because the eye looks better. The infection or virus may still be active. Stopping antibiotics or antiviral drops too soon can cause a rebound that is harder to treat. Finish the full course your veterinarian prescribes.

How to Reduce the Chance of It Happening Again

Feline herpesvirus is the most common cause of eye discharge, and once a cat has it, the virus stays in the body for life. You cannot cure it, but you can reduce flare-ups.

Reduce stress. Stress triggers herpesvirus outbreaks. Keep routines steady, provide hiding spots, and introduce changes slowly. If you are adding a new pet or moving house, talk to your vet about whether preventive measures are wise.

Keep the environment clean. Wash food bowls, water bowls, and bedding regularly. Use a mild, pet-safe disinfectant on surfaces. This reduces viral load in the home.

Support good nutrition. A balanced diet helps the immune system. Ask your veterinarian about supplements such as lysine. Evidence for lysine is mixed, so do not start it without professional advice.

Manage chronic cases. Some cats need long-term care. This may include daily eye lubrication, periodic antiviral medication, or regular check-ups. The American Animal Hospital Association offers guidance on preventive care and managing chronic conditions.

What Recovery and Ongoing Management Usually Look Like

Recovery time depends on the cause. A simple bacterial infection often improves within a few days of starting antibiotics. A herpesvirus flare can take one to two weeks to settle, and some cats have recurring episodes throughout their lives.

During recovery, you may need to clean the eye several times a day and give medication as directed. Your cat might need an Elizabethan collar, often called a cone, to stop pawing at the eye. This is normal and temporary.

For cats with frequent flare-ups, management becomes a routine. You will learn your cat's early warning signs, such as slight redness or increased tearing, and act quickly. Many cats live comfortably with herpesvirus for years with good care.

Follow-up visits matter. Your veterinarian may want to recheck the eye to confirm healing. The MSD Veterinary Manual explains that eye conditions can have multiple causes, and confirming the diagnosis is essential for proper treatment.

Frequently Asked Questions

Can I use saline solution to rinse my cat's eye at home?

Plain sterile saline, the kind used for contact lenses, is generally safe for a gentle rinse. Do not use contact lens cleaning solution, which contains preservatives. Warm the saline to body temperature. Tilt the cat's head slightly and let the saline flow over the eye. Do not squeeze the bottle directly onto the eyeball. This can help remove debris, but it does not treat infection. If discharge continues for more than a day, see your veterinarian.

My cat has one watery eye. Is that an emergency?

A single watery eye is not always an emergency, but it needs attention. It could be a scratch, a foreign object, or a blocked tear duct. If your cat is not squinting and the eye is not red, you can monitor for 24 hours. If the eye becomes red, the cat squints, or discharge turns yellow or green, call your vet that day. If the cat is in obvious pain, seek emergency care.

How do I know if my cat is in pain from an eye problem?

Cats hide pain well, but eye pain has clear signs. Squinting is the most reliable sign. The cat may hold the eye partially or fully closed. Pawing at the eye, rubbing the face on furniture, and avoiding light are other clues. A cat that suddenly becomes withdrawn or stops eating may also be in pain. Any of these signs warrant a veterinary visit.

Will my cat go blind from eye discharge?

Most cases of eye discharge do not cause blindness. However, untreated infections or ulcers can scar the cornea, the clear front surface of the eye, and permanently reduce vision. Deep ulcers can even rupture the eye. The risk of blindness is real but preventable with prompt care. If your cat is squinting or has colored discharge, do not delay treatment.

Can I use a warm compress on my cat's eye?

Yes, a warm compress can be soothing and can help soften dried discharge. Use a clean, soft cloth soaked in warm water. Wring it out well so it is damp, not dripping. Hold it gently over the closed eye for one to two minutes. Do not press. This is a comfort measure, not a treatment. It does not replace veterinary care for an active infection.

My cat had herpesvirus once. Will it always come back?

The virus stays in the body for life, but not every cat has frequent flare-ups. Some cats have one episode and then go years without another. Others have several outbreaks per year. Triggers include stress, illness, and immune suppression. You can reduce flare-ups by keeping stress low and maintaining good general health. Work with your veterinarian to create a plan for your cat's specific pattern.

Related Clinical & Scientific Guides

• Dog Heatstroke: Emergency Cooling Steps and When to Rush
• Dog Vomiting: When to Call the Vet and What to Do at Home
• How to Make a Dog Vomit Safely at Home: When and How

References and Further Reading

• AVMA Telehealth and Veterinary Telemedicine
• FDA Veterinary Telemedicine Information
• AVMA Pet Owner Resources
• MSD Veterinary Manual Pet Owner Version
• AAHA Pet Owner Resources

Related Articles

• Cat Hair Loss: Causes and When to See a Vet
• Cat Eye Injury: Signs, First Aid, and When to See the Vet
• Cat Skin Rash: Causes, Home Care, and When to See the Vet
• Cat Eye Discharge: Normal or Infection?
• Cat Sneezing: Common Causes and When to Worry

This article is general educational information for pet owners. It is not a substitute for veterinary diagnosis, examination, or treatment. If your pet is showing severe or rapidly worsening signs, contact an emergency veterinary hospital immediately.