Why is my cat sneezing: causes, home care & when to call the vet
A plain-English guide to sneezing in cats — what\'s usually fine, what isn\'t, and what to do today.
An occasional sneeze in a healthy cat is no more concerning than it is in a human — a passing irritant, a speck of dust, or a brief startle. Persistent sneezing is a different matter: cats almost always have an underlying cause when sneezing lasts more than a few days, and the older the cat, the more important it is to investigate.
Bouts of sneezing, especially with watery or coloured discharge from the eyes and nose, are most often "cat flu" — feline herpesvirus or calicivirus. These viruses are common, often picked up as kittens, and can flare up under stress for the cat's entire life. They are not usually dangerous to a healthy adult cat but can be life-threatening in kittens.
Chronic one-sided nasal discharge in a senior cat — different from intermittent bilateral sneezing — is one of the patterns that always warrants imaging. Tumours, polyps, and tooth root infections all sit in that picture.
Common causes
Feline upper respiratory infection (cat flu)
See a vet within 24–48 hoursFeline herpesvirus or calicivirus. Sneezing, watery or yellow-green nasal/eye discharge, fever, appetite loss. Often flares with stress for life.
Read more about feline upper respiratory infection (cat flu) →Allergies (atopy)
Monitor at homeDust, pollen, mould, cigarette smoke, certain cleaning products. Sneezing without discharge, sometimes with skin signs.
Foreign body in the nose
See a vet within 24–48 hoursGrass seed, blade of grass, small object. Sudden onset violent sneezing, pawing at the face, sometimes one-sided discharge.
Dental disease
See a vet within 24–48 hoursUpper tooth root infection can break into the nasal cavity, causing one-sided nasal discharge.
Read more about dental disease →Nasopharyngeal polyp
See a vet within 24–48 hoursBenign growth, more common in young cats. Persistent one-sided sneezing, noisy breathing, sometimes head tilt.
Nasal tumour
See a vet within 24–48 hoursSenior cats. Chronic one-sided discharge, sometimes with bleeding, facial swelling, or eye changes. Imaging needed.
Fungal infection (cryptococcosis)
See a vet within 24–48 hoursIn some geographies. Persistent nasal discharge, sometimes with a visible mass at the nostril or a swelling on the bridge of the nose.
What you can safely do at home
- Keep the cat indoors, warm, and out of dust and smoke.
- Wipe discharge from the eyes and nose gently with a damp cotton pad.
- Encourage eating with warmed strong-smelling wet food — congested cats can't smell food and may stop eating.
- Run a humidifier or take the cat into a steamy bathroom for 10 minutes once or twice a day.
- Isolate from other cats during acute upper respiratory illness — these viruses are highly contagious.
- Keep the cat's litter, food, and water in one easy-to-reach room while they recover.
These steps are general guidance for an otherwise well, healthy adult pet. If your cat is a puppy/kitten, a senior, or has a known chronic condition, call a vet rather than waiting it out.
What to expect at the vet
The vet will usually:
- Full physical including nasal exam, dental exam, lymph node check
- PCR test of nasal/conjunctival swab for herpes, calici, mycoplasma, chlamydia
- Bloodwork in chronic cases or in kittens
- Dental X-rays where dental cause is suspected
- CT scan or rhinoscopy for persistent one-sided signs in senior cats
Useful questions to ask:
- Is this herpes/calici, or something more serious?
- Should we image the nose and head?
- If it's herpes, what can we do for future flare-ups?
- Is L-lysine supplementation evidence-based?
- When should I worry about this becoming a tumour rather than chronic flu?
How to reduce the chance of it happening again
- Vaccinate kittens against feline herpesvirus and calicivirus, and keep boosters current.
- Minimise stress for cats with known herpesvirus — stable routine, hiding spaces, food puzzles.
- Avoid smoking in the home and minimise harsh cleaning chemicals.
- Annual dental exam to catch tooth root disease before it breaks into the nasal cavity.
- Watch outdoor-access cats for sudden violent sneezing after walks in long grass — grass seeds are a common foreign body.
- Senior cats over 10 with new one-sided nasal signs warrant earlier rather than later imaging.
Frequently asked questions
Is cat flu serious?
For most healthy adult cats, no — it's an unpleasant 1–2 week flare with full recovery. For kittens, immunocompromised cats, or cats with secondary bacterial infections, it can be very serious and warrants vet care.
Will L-lysine help my cat's recurring herpes flare-ups?
The evidence is mixed and recent reviews don't strongly support routine L-lysine. Stress reduction, environmental enrichment, and prompt treatment of flare-ups have stronger evidence.
Should I worry about one-sided nasal discharge?
Yes — particularly in a senior cat. One-sided chronic signs (especially with bleeding, facial swelling, or noise) raise the index of suspicion for polyp, tumour, fungal infection, or dental root abscess. Imaging is usually warranted.
Can my cat's sneezing infect me or my dog?
No — feline herpesvirus and calicivirus are species-specific. They are highly contagious between cats but harmless to humans and dogs.
My cat sneezes only when it's windy outdoors — is that allergies?
Likely environmental irritation or seasonal allergies. If sneezing is brief, infrequent, and the cat is otherwise well, it can be managed at home. Worsening pattern, discharge, or appetite change warrants a vet check.