Upper Respiratory Infections in Cats: Symptoms and Treatment
Sneezing, watery eyes, and a cat who suddenly turns their nose up at food — upper respiratory infections (URIs) are one of the most common reasons cats end up at the vet, especially cats from shelters, multi-cat households, or anywhere cats have been stressed or crowded. The short answer: most cases are viral, most resolve with supportive care at home within one to two weeks, and the infection rarely needs to be dramatic to still need a vet’s attention.
Here’s what’s actually going on, what you can do about it, and when “just a cold” stops being just a cold.
What Causes Upper Respiratory Infections in Cats?
The overwhelming majority of feline URIs trace back to two viruses: feline herpesvirus-1 (FHV-1) and feline calicivirus (FCV). Together they account for the bulk of cases seen in general practice, according to the American Association of Feline Practitioners (AAFP). Bacterial players like Bordetella bronchiseptica and Chlamydia felis show up too, sometimes alone, often as secondary invaders once a virus has already broken down the cat’s natural defenses.
A few things worth knowing about these viruses:
- FHV-1 is essentially permanent. Once a cat is infected, the virus goes dormant in nerve tissue and can reactivate later — usually during stress, illness, or a move to a new home. This is why some cats get recurring “colds” for life.
- FCV mutates readily, which is part of why no vaccine gives complete protection and why cats can get reinfected with different strains.
- Stress is a genuine trigger, not a folk theory. Shelters, boarding facilities, and multi-cat homes see far higher URI rates, and cortisol release is believed to reactivate latent herpesvirus specifically.
Kittens, senior cats, and cats with compromised immune systems (FIV-positive cats, cats on immunosuppressive medication) tend to get hit harder and for longer.
Symptoms to Watch For
Feline URIs look a lot like a human cold, which is exactly what makes them easy to underestimate:
- Sneezing, sometimes in fits
- Clear or colored nasal discharge
- Watery or goopy eye discharge, sometimes with visible conjunctivitis
- Congestion (you’ll hear it before you see it)
- Reduced appetite — cats rely heavily on smell to want to eat, so a blocked nose can mean a cat that simply stops eating
- Mild fever and lethargy
- Occasionally, mouth ulcers (more typical of calicivirus) or corneal ulcers (more typical of herpesvirus)
Most otherwise-healthy adult cats will show mild versions of the above and start improving within 7–10 days.
How Vets Diagnose and Treat URIs
Diagnosis is usually clinical — a vet examining a sneezing, congested cat with normal bloodwork rarely needs to run viral panels to know what they’re dealing with. PCR testing exists and gets used in shelter medicine, in cats with unusually severe or persistent signs, or when it will actually change the treatment plan.
Treatment is largely supportive, because these are viral infections that mostly need to run their course:
- Keep the face clean. Gently wipe nasal and eye discharge with a warm, damp cloth so it doesn’t crust over and block the nostrils further.
- Encourage eating. Warming wet food slightly boosts the smell and can coax a congested cat to eat. Strong-smelling foods (tuna, warmed chicken) can help bridge a few rough days.
- Humidity helps. Running a humidifier, or letting your cat sit in a steamy bathroom for a few minutes, can loosen nasal congestion.
- Antibiotics are appropriate only when a vet suspects a secondary bacterial infection (thick, colored discharge, fever that isn’t resolving) — they do nothing against the underlying virus.
- Antivirals, such as famciclovir, are reserved for more severe or recurrent herpesvirus cases, particularly with corneal ulceration, and require a prescription and vet oversight.
- L-lysine supplementation, once a near-universal recommendation for herpesvirus-positive cats, has fallen out of favor with many veterinary organizations after several studies failed to show a meaningful benefit — worth discussing with your vet rather than assuming it’s still standard of care.
Can You Prevent Them?
Not entirely, but you can reduce frequency and severity:
- Vaccination (the FVRCP core vaccine) doesn’t prevent infection outright but significantly reduces severity and shedding — it’s one of the core vaccines recommended for essentially every cat.
- Reduce stress where you can, especially around moves, new pets, or boarding — a genuinely hard thing to control fully, but worth factoring in if your cat is prone to recurrence.
- Isolate sick cats in multi-cat households. FHV-1 and FCV spread through direct contact and shared surfaces (bowls, litter boxes, bedding), so separating a sneezing cat and washing your hands between handling cats meaningfully slows transmission.
When to See a Vet
Most mild URIs can be managed at home with monitoring, but see a vet promptly if:
- Your cat stops eating or drinking for more than 24 hours
- Breathing looks labored, open-mouthed, or unusually fast at rest
- Discharge becomes thick, yellow-green, or foul-smelling
- You notice squinting, cloudiness, or visible ulcers on the eye — herpesvirus-related corneal ulcers can threaten vision if untreated
- Symptoms last beyond two weeks without improvement
- The cat is a kitten, a senior, pregnant, or has an existing health condition — URIs hit these groups harder and faster
If you’re not confident your current vet takes concerns like this seriously, how to find a good vet is worth a read before you need one urgently.
The Practical Takeaway
A sneezing cat with clear eyes and a normal appetite is usually fine to monitor at home for a few days. A cat that stops eating, struggles to breathe, or has eye involvement needs a vet, not a wait-and-see approach. If your cat’s breathing problems sound more like wheezing or coughing fits than sneezing and congestion, it’s worth ruling out feline asthma instead, since the two get confused often and are treated very differently. And if eye discharge is the dominant symptom rather than sneezing, our guide to cat eye discharge breaks down what’s normal versus what needs attention.