Nasal Discharge in Cats: Causes, Colors, and When to See a Vet
Nasal discharge in cats is most commonly caused by upper respiratory tract infections — primarily feline herpesvirus-1 (FHV-1) and feline calicivirus — and often appears as clear-to-white mucus paired with sneezing. Yellow or green discharge, discharge from only one nostril, or discharge with nosebleeds, facial swelling, or difficulty breathing shifts the picture toward a bacterial secondary infection, nasal polyp, foreign body, or something more serious. Duration matters: any discharge persisting beyond 10–14 days warrants a vet visit.
A runny nose on a cat is easy to dismiss — cats sneeze, and some discharge is normal after sneezing. But the color, which nostril is involved, and what else is happening alongside the discharge are important clinical clues. Here is what the presentation typically tells you.
What Color Is the Discharge, and What Does It Mean?
Color is one of the most useful things to note before calling your vet.
| Discharge color / type | Most likely significance |
|---|---|
| Clear, watery, both nostrils | Early viral upper respiratory infection (FHV-1, calicivirus), allergy, or environmental irritant |
| White, slightly opaque | Early-to-mid viral infection, mild secondary bacterial component |
| Yellow or green, one or both nostrils | Secondary bacterial infection (most common after viral URI), or chronic sinusitis |
| Bloody or reddish-brown | Nasal polyp, nasal tumor, fungal rhinitis, severe infection, or coagulation problem |
| Thick and crusty, one nostril only | Nasal foreign body, polyp, or early nasal tumor |
| Discharge with noisy breathing, open-mouth breathing | More severe airway involvement — call the vet today |
Feline herpesvirus-1 (FHV-1) is one of the most common causes of recurrent nasal discharge in cats. After initial infection, FHV-1 establishes latency in the trigeminal ganglion and can reactivate during stress, producing recurrent episodes that look like "another cold." This recurrence pattern is characteristic and differs from a new infection each time. The AAHA-AAFP Feline Life Stage Guidelines, 2021 address FHV-1 as a core consideration in feline preventive and chronic care planning.
Other Causes Beyond Upper Respiratory Infection
Upper respiratory infection is the most common cause of nasal discharge in cats, but the differential is broader:
Nasal polyps: Benign growths from the nasopharynx or middle ear region are common in young-to-middle-aged cats, often presenting with discharge and stertor (noisy breathing through a partially blocked airway). They are typically not painful and not malignant, but they obstruct airflow and harbor secondary infection.
Nasal foreign bodies: Grass blades, seeds, or small objects inhaled during outdoor activity or play can lodge in the nasal passage, causing sudden-onset one-sided discharge that is sometimes bloody. This often accompanies vigorous pawing at the nose.
Fungal rhinitis (Cryptococcus): Caused by Cryptococcus neoformans, this is less common than in dogs but does occur in cats and presents as progressive, often unilateral discharge that may be blood-tinged, sometimes with visible swelling over the bridge of the nose.
Dental disease: Roots of the upper canine and premolar teeth sit close to the nasal floor. Severe dental abscesses or fistulas can drain into the nasal passage and present as persistent unilateral discharge — a reason your vet may recommend a dental exam alongside nasal imaging.
Nasal tumors: Less common than in dogs, but nasal tumors in cats most often present in middle-aged to older cats as progressive unilateral discharge that becomes bilateral and may be bloody, sometimes with facial deformity. See the article on cat upper respiratory infection signs for comparison with the more common presentation.
When to See a Vet
Call your vet today if:
- Nasal discharge has lasted more than 7–10 days without improvement
- Discharge is yellow, green, or bloody
- Only one nostril is producing discharge (asymmetric discharge is more likely to indicate local disease than a simple cold)
- Your cat has stopped eating, is lethargic, or has a fever (ears or paws feel notably hot)
- Breathing sounds labored, noisy, or open-mouthed
- You can see visible swelling on the bridge of the nose or under one eye
Go to the ER immediately if:
- Your cat is open-mouth breathing or appears to be struggling for air — cats have small nasal passages and can become severely compromised when both are blocked
- Your cat has not eaten for more than 24–36 hours and is visibly weak
- There is significant blood coming from the nose
This article is general educational information and is not a diagnosis or substitute for examination by a licensed veterinarian.
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Frequently Asked Questions
Is nasal discharge in cats contagious to other cats? If the cause is viral (FHV-1, calicivirus) or bacterial, yes — these agents spread through direct contact and shared food/water bowls, litter boxes, and grooming. Isolate a cat with active discharge from other cats in the household during illness. FHV-1 establishes lifelong latency in nearly all exposed cats; stress reactivation is not contagious in the way primary infection is, but still sheds virus.
Can a cat's nasal discharge go away on its own? Mild viral upper respiratory infections often resolve in 7–14 days in otherwise healthy adult cats. Kittens, immunocompromised cats (FIV-positive, on corticosteroids), and senior cats are at greater risk of the infection becoming more severe or prolonged. Discharge that doesn't improve in 10–14 days, or that is present only in one nostril, is less likely to resolve without intervention.
What is the treatment for nasal discharge in cats? Treatment depends on the cause. Viral URI is typically managed supportively (keeping the nose clean, ensuring the cat is eating, humidified air, sometimes an L-lysine supplement — though evidence for L-lysine is mixed in the literature). Bacterial secondary infections are treated with antibiotics. Polyps require surgical removal. Fungal rhinitis requires antifungal medication. Nasal tumors may require radiation. Your vet will need to examine and test your cat to identify the cause.
How much does treating nasal discharge in cats cost? A basic exam costs $50–150. Bloodwork (CBC, chemistry) runs $100–250. Imaging (nasal X-rays or CT scan for persistent cases) ranges from $150–800+. Nasal cytology or biopsy adds cost depending on the technique. Treatment varies widely: antibiotics are relatively inexpensive; antifungals, polyp removal, or tumor treatment are substantially more involved and costly.
My cat has nasal discharge but is eating normally and acting fine — should I still call the vet? If discharge is clear to white, from both nostrils, and your cat is eating, drinking, and behaving normally, brief monitoring is reasonable. If discharge is still present at 7–10 days, becomes colored or one-sided, or if your cat's appetite or energy drops, call your vet. Cats that stop eating even for 24–48 hours are at risk of hepatic lipidosis (fatty liver disease), so any reduction in food intake warrants a faster call.
Is there a vaccine for feline upper respiratory infection? Yes — FHV-1 and calicivirus vaccines are core vaccines recommended for all cats by AAFP guidelines. These vaccines do not prevent infection entirely but reduce severity and duration of clinical signs. Cats can still develop mild upper respiratory symptoms even when vaccinated.
Can nasal discharge in cats be caused by allergies? Environmental allergies (pollens, dust, mold) can cause mild watery nasal discharge and sneezing in cats, but allergic rhinitis is much less common in cats than in dogs or humans. Persistent, colored, or one-sided discharge is not typical of allergy alone and warrants investigation for other causes.
Still Not Sure if Your Cat Needs a Vet?
This article covers what's typical. Your cat's age, immune status, FHV-1 history, and whether they're still eating change what "wait and see" vs. "call tonight" means specifically for them. Voyage AI Vet triages in under 2 minutes — describe what you're seeing in chat, share photos of the discharge color and which nostril, or hop on a live video call if you want a second pair of eyes. Every answer comes with citations to the actual veterinary literature it's pulling from.