The sneezing starts, then the runny nose, then the gummy, half-closed eyes — and suddenly your cat looks miserable in a way that seems awfully familiar. People often call it a "cat cold," and the comparison isn't far off: what you're usually seeing is a feline upper respiratory infection (URI), the feline equivalent of a bad head cold. Most cases are viral, most resolve with good supportive care, and most cats bounce back within a week or two. But a few red flags turn a nuisance into a real problem, and the two viruses behind most infections have a habit of never fully leaving. Here's what's going on inside a sneezing cat, how to help at home, and when to call the vet.

What Causes a Cat Cold

Feline upper respiratory infections are common, especially in crowded settings like shelters, breeding catteries, and feral colonies, where highly contagious pathogens spread easily. The great majority of cases trace back to two viruses: feline herpesvirus-1 (also called feline viral rhinotracheitis, or FVR) and feline calicivirus (FCV). Together they account for the vast majority of URIs. Bacteria such as Chlamydia felis and Bordetella bronchiseptica can cause or complicate infections, and less commonly fungi or other organisms are involved.

These pathogens spread through direct contact and through the droplets a cat scatters when it sneezes, as well as via shared bowls, bedding, litter boxes, and human hands. That's why a single sneezing newcomer can seed an outbreak through an entire household or shelter. Kittens, seniors, unvaccinated cats, and cats under stress or with weakened immune systems are the most vulnerable, and stress alone can reactivate a dormant infection in a cat that caught the virus years earlier.

The Signs to Watch For

A classic feline URI looks a lot like a human cold concentrated around the nose and eyes. Typical signs include:

Because congestion dulls a cat's sense of smell, and because mouth ulcers make chewing hurt, appetite loss is one of the most important things to monitor. A cat that stops eating for more than a day or two needs veterinary attention regardless of how mild the sniffles look.

Feline Herpesvirus: The Lifelong Houseguest

Feline herpesvirus is extraordinarily common — up to 97% of cats are exposed in their lifetime, and the virus establishes a lifelong infection in up to 80% of exposed cats. Of those, roughly 45% will shed the virus periodically, typically when stressed by things like boarding, a move, a new pet, or surgery. Beyond the usual respiratory signs, herpesvirus is notorious for causing eye disease: recurring conjunctivitis and, in more serious cases, ulcers on the cornea (keratitis).

Because the virus stays for life, many cats experience occasional flare-ups rather than a single one-and-done illness. The good news is that these flare-ups are often mild and clear on their own, and reducing stress genuinely helps keep the virus quiet. One popular remedy worth flagging: lysine supplementation is controversial, and several studies suggest it is not effective and may even worsen symptoms and promote viral shedding. Talk to your vet before reaching for it.

Feline Calicivirus: More Than a Sniffle

Calicivirus is another highly contagious, worldwide feline virus. In small groups roughly 10% of cats are infected, but in crowded conditions like shelters that figure can climb to 90%. Most infected cats develop ordinary upper respiratory signs, but calicivirus has a signature feature: painful ulcers on the tongue, gums, or hard palate. It can also spread to the lungs and cause pneumonia, sometimes worsened by secondary bacterial infection.

Rarely, a severe systemic form of calicivirus occurs, causing swelling of the head and limbs, crusting sores, jaundice, and internal bleeding; this form is fatal in roughly two-thirds of affected cats. It is uncommon, but it's the reason any cat that becomes suddenly and severely ill — not just snuffly — deserves urgent care rather than watchful waiting at home.

How Vets Diagnose and Treat It

In most straightforward cases, a veterinarian diagnoses a URI simply by recognizing the signs, especially in a young or unvaccinated cat, and doesn't need to pin down the exact virus because the supportive treatment is similar either way. When identification matters — recurrent cases, severe illness, or a shelter outbreak — PCR testing of swabs from the eyes, nose, or mouth can detect viral genetic material.

There is no magic cure for the viruses themselves, so treatment centers on supportive care: keeping the cat hydrated, nourished, and comfortable while its immune system does the work. Depending on the case, a vet may prescribe antibiotics for secondary bacterial infections, antiviral or eye medications for herpesvirus-related keratitis, pain relief for mouth ulcers, or fluids for a dehydrated cat. In severe cases, hospitalization or a temporary feeding tube may be needed to get a cat through the worst of it. Antibiotics don't touch the underlying virus, so they're reserved for when bacteria have joined in.

Caring for a Cat Cold at Home

For a mild case your vet has cleared for home care, a few things make a real difference:

Never give human cold medicines to a cat. Many, including decongestants and pain relievers like acetaminophen, are toxic to cats and can be fatal. Only use medications your veterinarian prescribes.

When to Call the Vet

Book a visit — or seek urgent care — if your cat shows any of these:

Prevention: Vaccines and Common Sense

The core FVRCP vaccine protects against feline herpesvirus and calicivirus (as well as panleukopenia) and is recommended for all cats. Vaccination doesn't guarantee a cat will never catch these ubiquitous viruses, and it doesn't cure a cat that's already infected — but it significantly reduces the severity of disease and the amount of virus a cat sheds, which protects both your cat and any others it lives with. Keeping the vaccination schedule current is the single most effective step you can take.

Beyond vaccines, prevention comes down to limiting exposure and stress: keep new or sick cats separate until they're healthy, don't share bowls between a sick cat and healthy ones, disinfect shared surfaces, and give your cat a calm, enriched environment that keeps latent herpesvirus dormant. For most households, a fully vaccinated, low-stress, indoor cat will weather the occasional sniffle without much drama — and now you'll know exactly what you're looking at when the sneezing starts.