Cat Flu: Why Your Cat Is Sneezing, Snotty, and Watery-Eyed — and How to Help

If your cat has suddenly started sneezing in bursts, developed weepy or crusted eyes, and is breathing through a blocked, snotty nose, there's a good chance you're looking at cat flu — the everyday name for a feline upper respiratory infection (URI). It is one of the most common illnesses cats get, and for most healthy adult cats it is more miserable than dangerous, much like a heavy cold in a person. But in kittens, elderly cats, and cats with other health problems it can turn serious, and a handful of warning signs always mean a vet visit rather than a wait-and-see.

This article explains what cat flu actually is, why some cats seem to carry it for life, how to nurse a cat through an episode at home, and exactly when sneezing stops being a nuisance and becomes an emergency.

What Cat Flu Actually Is

"Cat flu" is a slightly misleading name — it has nothing to do with human influenza and you cannot catch it from your cat. It is an infection of the upper airways: the nose, sinuses, throat, and the membranes around the eyes. Roughly 90% of cases are caused by one of two viruses:

• Feline herpesvirus (FHV-1), also called feline viral rhinotracheitis. It tends to cause the more severe eye and nose signs, and — importantly — it never fully leaves the body once a cat is infected.
• Feline calicivirus (FCV), which is more often associated with mouth ulcers, drooling, and sometimes a transient limping or lameness.

A minority of cases involve bacteria such as Bordetella bronchiseptica or Chlamydia felis, and bacteria frequently move in as a secondary infection on top of the original virus — which is why a clear, watery discharge that turns thick, yellow, or green often signals that bacteria have joined the party.

Vet Justine Lee explains what an upper respiratory infection is, why it isn't really a "cold," and what those runny eyes and sneezes are telling you.

How Cats Catch It

Cat flu spreads the way human colds do — through respiratory secretions. A sneezing cat fires virus-laden droplets into the air and onto surfaces; the viruses also travel on shared food bowls, bedding, litter trays, and on human hands and clothing. Direct nose-to-nose contact, mutual grooming, and shared spaces all pass it along.

This is why cat flu is so strongly associated with multi-cat environments: shelters, rescues, breeding catteries, feral colonies, and any home with several cats. Stress and crowding both raise the odds, which is part of why so many newly adopted kittens arrive home already sneezing.

The Symptoms to Recognise

Cat flu usually announces itself with a cluster of signs rather than just one:

• Sneezing, often in repeated fits.
• Nasal discharge — clear and watery at first, sometimes thickening to yellow or green.
• Runny, red, or gummy eyes (conjunctivitis), with discharge that can crust the lids shut, especially in kittens.
• A blocked, congested nose and noisy or snuffly breathing.
• Reduced appetite — a cat that can't smell its food often won't eat it.
• Drooling or mouth ulcers, more typical of calicivirus.
• Lethargy, a mild fever, and a general "off-colour" droop.

In an otherwise healthy adult, these signs usually peak over a few days and settle within one to three weeks. The danger zone is the cat that stops eating, the kitten that becomes quiet and dehydrated, or any cat whose breathing becomes laboured.

A vet walks through the runny-nose, snotty, watery-eyed picture of cat flu — what's normal, what's worrying, and when to book an appointment.

The "Carrier Cat": Why It Keeps Coming Back

Here is the part that surprises many owners. A cat that recovers from feline herpesvirus doesn't truly get rid of it. The virus retreats into the nerves and lies dormant, and a large proportion of recovered cats become lifelong carriers. At times of stress — a house move, a new pet or baby, boarding, illness, or surgery — the virus can reactivate, and the cat flares up with sneezing and runny eyes all over again, sometimes shedding virus that can infect other cats.

This is why some cats seem to get "cat flu" two or three times a year for the rest of their lives. They aren't catching it fresh each time; their own dormant virus is waking up. The practical lesson is that managing stress is part of managing the disease — predictable routines, hiding spots, vertical space, and pheromone diffusers can all reduce how often a carrier cat flares.

Nursing a Cat Through It at Home

Because most cases are viral, there is usually no magic pill — treatment is supportive care that keeps the cat comfortable and eating while its immune system does the work. Your vet may add antibiotics if a secondary bacterial infection is suspected (thick coloured discharge), eye ointment for conjunctivitis, or occasionally an antiviral for severe herpesvirus. At home, the things that genuinely help:

• Keep the face clean. Gently wipe away eye and nose discharge several times a day with cotton wool dampened in warm water, softening any crusts so the cat can see and breathe.
• Use steam to loosen congestion. Sitting with your cat in a steamy bathroom for 10–15 minutes (run a hot shower) helps clear a blocked nose. A humidifier in the cat's room does the same job more gently.
• Tempt the appetite. A congested cat can't smell, and a cat that can't smell often won't eat. Offer warmed, strong-smelling wet food — gently heating it releases the aroma — and try tuna, sardines, or a favourite treat to get them started. A cat that stops eating entirely is an urgent problem.
• Keep them hydrated. Encourage drinking, offer wet food for its water content, and watch for signs of dehydration.
• Warmth, rest, and isolation. Keep the cat warm, quiet, and — if you have other cats — separated, with its own bowls and litter tray to limit spread.

One honest caveat on a popular remedy: L-lysine supplements are widely sold and recommended for herpesvirus, but good-quality reviews of the evidence have found no reliable benefit, so don't rely on it in place of proper nursing and veterinary care.

When Sneezing Becomes an Emergency

Most adult cats ride out cat flu at home with good nursing. But some situations need a vet promptly — and a few need one urgently. Call your vet if your cat shows any of these:

• Not eating for more than 24 hours (longer than that is genuinely dangerous, as cats can develop serious liver problems when they stop eating).
• Laboured, open-mouthed, or fast breathing — a sign the infection may have moved to the lungs, or that the cat is in real distress. This is an emergency.
• A young kitten, a senior cat, or a cat with another illness showing flu signs — these cats deteriorate fast.
• Eyes glued shut, a bulging eye, or cloudiness — eye complications can threaten sight.
• Marked lethargy, collapse, or obvious dehydration.
• Symptoms that drag on beyond a couple of weeks or keep returning, which may point to chronic infection or other nasal disease.

Prevention: Vaccination and Hygiene

You can't make a cat bulletproof, but you can dramatically lower the risk and severity. The core FVRCP vaccine protects against both main cat-flu viruses (the "FVR" is feline herpesvirus and the "C" is calicivirus, alongside panleukopenia). Vaccination doesn't always prevent infection outright, but it makes illness much milder — well worth keeping up to date, starting as a kitten and boosting through life as your vet advises.

Beyond the needle: wash hands and bowls between cats, isolate any sneezing newcomer before introductions, keep multi-cat homes clean and uncrowded, and — for carrier cats — keep stress low to reduce flares. If you foster or run a rescue, good ventilation and quarantine protocols are the single biggest lever you have.

The Bottom Line

Cat flu is common, usually self-limiting, and rarely serious in a healthy adult cat — but it is genuinely dangerous in kittens, seniors, and any cat that stops eating or struggles to breathe. Learn the picture: sneezing, snotty nose, weepy eyes, a quiet cat off its food. Nurse the mild cases at home with face-cleaning, steam, and tempting warm food, and don't hesitate to call your vet for the young, the old, the non-eaters, and the labour-breathers. And remember that for many cats this is a virus they carry for life, so a calm, low-stress home is one of the best long-term medicines you can offer.

This article is general information, not veterinary advice. If your cat is unwell — and especially if it has stopped eating or is having trouble breathing — contact your vet.