Quick answer
A cat upper respiratory infection is like a bad cold, usually caused by feline herpesvirus or feline calicivirus. Signs include sneezing, a runny nose, watery or gunky eyes and sometimes mouth ulcers or fever. Most cats recover in one to three weeks with rest and supportive care. See a vet if your cat stops eating, breathes with its mouth open, or is a young kitten.
Open-mouth breathing is never normal in a cat. Read more on a cat breathing fast, or use our should I take my cat to the vet? check if you aren’t sure how urgent it is.
What causes a cat upper respiratory infection?
A cat upper respiratory infection affects the nose, throat, eyes and sometimes the mouth. It’s often called cat flu, although it isn’t caused by influenza. Two viruses cause most cases: feline herpesvirus and feline calicivirus. Bacteria can cause infection on their own or move in once a virus has damaged the airways.
| Cause | Typical signs | Notes |
|---|---|---|
| Herpesvirus (FHV-1) | Sneezing, runny eyes, conjunctivitis, eye ulcers | Stays in the body for life and can flare with stress |
| Calicivirus (FCV) | Mouth and tongue ulcers, drooling, sneezing, limping in some kittens | Some cats keep shedding the virus for months |
| Bordetella bronchiseptica | Sneezing, cough, nasal discharge | Bacteria. More common in shelters and multi-cat homes |
| Chlamydia felis | Red, swollen, weepy eyes | Bacteria. Mainly affects the eyes |
| Mycoplasma | Eye and nose discharge | Bacteria. Often alongside a virus |
Cornell reports that up to 97% of cats are exposed to herpesvirus (FHV-1) during their lives. Infection is most common in kittens, shelter cats and homes with many cats.
How do cats catch cat flu?
The infection spreads through sneezes, nose and eye discharge, and saliva. Cats catch it by close contact, shared food and water bowls, litter boxes and bedding. It can also travel on your hands and clothes.
Signs usually appear a few days to about a week after exposure. A sick cat is contagious to other cats, so keep them in a separate room with their own bowls and litter box. Wash your hands after handling them.
Why do some cats become carriers?
After an FHV-1 infection, the virus hides in the nerves and never fully leaves. Cornell notes that up to 80% of infected cats become lifelong carriers. Stress, such as moving house, boarding or a new pet, can trigger a flare of sneezing and eye problems.
With FCV, some cats shed the virus in their saliva for months or longer after they recover, even when they look healthy.
How is a cat upper respiratory infection treated?
There’s no medicine that quickly cures the viruses, so treatment focuses on helping your cat feel better while their immune system does the work. What your vet recommends depends on how sick your cat is.
- Supportive care: fluids for dehydration and help with eating
- Antibiotics: only if your vet suspects a bacterial infection. They don’t kill viruses
- Antiviral medicine: sometimes prescribed for herpes, especially when the eyes are affected
- Eye medicine: drops or ointment for conjunctivitis or ulcers
- Pain relief: for painful mouth ulcers
- Hospital care: for cats that won’t eat, are dehydrated or have pneumonia
Cold and flu tablets for people often combine a decongestant with acetaminophen (paracetamol), and both can be deadly to cats. Keep human cold, flu and allergy products away from your cat. If mouth ulcers seem painful, ask your vet for cat-safe pain relief instead of reaching for ibuprofen or aspirin.
For a sense of costs, most mild cases need one exam and possibly medication. See how much a cat vet visit costs.
How can I care for a cat with a cold at home?
Good home care makes a real difference. Cats rely on smell to want food, so a blocked nose often stops them eating.
- Warm the food. Slightly warmed wet food smells stronger. Strong-smelling food like fish-flavored varieties can help
- Clear the nose and eyes. Gently wipe discharge with a soft cloth or cotton pad dampened with warm water
- Add steam. Sit with your cat in the bathroom while a hot shower runs for 10 to 15 minutes, a few times a day
- Keep water close. Offer fresh water in several places, and wet food for extra fluid
- Keep them warm and quiet. Rest and low stress help recovery
- Track eating. Write down what your cat eats each day. A cat that stops eating needs a vet
Sneezing that lasts for weeks or keeps coming back may be something other than a simple infection. Our guide to a cat sneezing a lot covers other causes.
How long does a cat cold last?
Most cats with a mild infection improve within 7 to 10 days and recover fully in one to three weeks. Kittens, older cats and cats with other illnesses can take longer and are more likely to need treatment.
Call your vet if your cat isn’t improving after a week, gets worse at any point, or develops a thick yellow or green discharge. That can mean a bacterial infection has set in.
Rarely, FCV causes a severe form that spreads through the whole body, with fever, facial swelling and bleeding. It’s an emergency and needs hospital care.
How do I prevent cat flu?
Vaccination is the best protection. The core FVRCP vaccine covers herpesvirus and calicivirus. It doesn’t always stop infection, but it makes illness much milder and shortens it. Check our kitten vaccine schedule to make sure your kitten is covered.
Other ways to lower the risk:
- Keep a new cat separate for about two weeks before introducing them
- Reduce stress for cats known to carry herpesvirus
- Clean bowls, litter boxes and bedding regularly, especially in multi-cat homes
- Keep adult cats up to date on boosters
For other common illnesses and what to expect, browse our cat health problems guides.
Frequently asked questions
Can I catch an upper respiratory infection from my cat?
The viruses that cause most cat colds, feline herpesvirus and calicivirus, don't infect people. Wash your hands after handling a sick cat so you don't carry the virus to your other cats.
Will a cat upper respiratory infection go away on its own?
Mild cases often clear up in one to three weeks with good home care. Call your vet if your cat stops eating, gets worse after a few days or isn't improving after a week.
Why does my cat keep getting cat flu?
Feline herpesvirus stays in the body for life. Stress, another illness or some medicines can wake it up and cause a flare of sneezing and eye problems. Your vet can help you manage flare-ups.
Sources
Written by the CatsMed Team from the sources above. This guide isn’t reviewed by a veterinarian and isn’t a substitute for one. See how we research.
