Most upper respiratory infections (URIs) in cats are viral and resolve on their own within 7 to 10 days with supportive care at home. The two most common culprits are feline herpesvirus and feline calicivirus, which together account for the vast majority of cases. Treatment focuses on keeping your cat comfortable, hydrated, and eating while their immune system fights off the infection. Antibiotics don’t treat the virus itself but are sometimes prescribed to handle secondary bacterial infections that pile on while the cat is vulnerable.
What a Feline URI Looks Like
The hallmark signs are sneezing, nasal discharge (clear or colored), watery or goopy eyes, and congestion. You may also notice mouth ulcers, lethargy, and loss of appetite. Most cats with a mild URI still move around the house, drink water, and eat at least a little. A moderate case involves thicker nasal discharge, eye swelling, and a noticeable drop in appetite, often because the congestion blocks their sense of smell.
Severe cases look different. Open-mouth breathing in a cat is always an emergency, as cats are obligate nose-breathers and will only resort to mouth breathing when they’re in real distress. Other red flags include blue-tinged gums, rapid or labored breathing, standing with elbows pointed outward and neck stretched forward, complete refusal to eat or drink for more than 24 hours, and collapse. Any of these warrant an immediate vet visit.
Supportive Care at Home
The University of Wisconsin Shelter Medicine program emphasizes that supportive care should focus on minimizing discomfort, promoting hydration, maintaining nutrition, and keeping the nose and eyes clear of dried discharge. Handling should be kept to a minimum and ideally done by one consistent person to reduce stress, which genuinely slows recovery in cats.
Clearing Congestion
Gently wipe away crusty discharge from your cat’s nose and eyes with a warm, damp cloth several times a day. A congested cat can’t smell its food, which is the number-one reason sick cats stop eating. Saline nasal drops can help hydrate the nasal passages, though some cats find the process stressful enough to outweigh the benefit. If your cat tolerates it, a drop or two of plain saline (not medicated nasal spray) in each nostril can loosen things up. Another option: bring your cat into the bathroom while you run a hot shower for 10 to 15 minutes. The steam helps thin mucus naturally without any direct handling.
Getting a Congested Cat to Eat
Loss of appetite is one of the most dangerous aspects of a URI because cats who stop eating entirely for more than two to three days risk liver problems. Since congestion kills their sense of smell, everything you do should aim to make food as aromatic and appealing as possible.
Warm the food slightly to release more scent. Offer strong-smelling options like strained chicken or lamb baby food (check the label for onion or garlic powder, which are toxic to cats). Add warm, low-sodium chicken broth to their regular food. If your cat still refuses, try placing a tiny amount of food on their lips or paw to trigger a licking reflex. Offer several small, fresh meals throughout the day rather than one large bowl. Use a wide, shallow dish so the sides don’t press against your cat’s whiskers, which can discourage eating. Gentle petting and back stroking while food is present can also nudge a reluctant cat into taking a few bites.
If the environment is loud or stressful, covering part of the cat’s resting area with a towel or blanket can create a calmer space. Reducing noise exposure, maintaining normal light and dark cycles, and keeping the room at a comfortable temperature all help lower stress and encourage eating.
Hydration
Dehydration compounds everything. Offer fresh water in multiple spots, and consider a pet water fountain if your cat prefers running water. Wet food and broth-based meals pull double duty by providing both calories and fluids. If your cat’s skin stays “tented” when you gently pinch it at the scruff (rather than snapping back flat), that’s a sign of dehydration that needs veterinary attention.
When Veterinary Treatment Is Needed
A vet visit is warranted if symptoms last beyond 10 days, if your cat stops eating for more than a day, if nasal discharge turns thick and yellow or green (suggesting bacterial infection), if eye swelling worsens, or if you see mouth ulcers. Kittens, elderly cats, and cats with weakened immune systems are at higher risk of complications and should generally be seen sooner rather than later.
For bacterial infections layered on top of the virus, vets typically prescribe antibiotics like doxycycline or amoxicillin as first-line options. Cats with chronic bacterial rhinitis sometimes need weeks of antibiotic treatment because the infection can settle into the cartilage and bone of the nasal passages. If a cat is too difficult to medicate orally, injectable antibiotics that last for about two weeks are available.
For herpesvirus infections specifically, an antiviral medication called famciclovir is the current drug of choice. It’s used for both acute flare-ups and chronic cases. Eye infections caused by herpesvirus may be treated with antiviral eye drops applied twice daily. Your vet may also prescribe pain medication if mouth ulcers or severe congestion are making your cat visibly uncomfortable.
Skip the Lysine Supplements
Lysine (L-lysine) has been widely recommended for years as a supplement to prevent or treat herpesvirus flare-ups in cats. The theory was that lysine would lower levels of another amino acid that the virus needs to replicate. A systematic review published in BMC Veterinary Research found that this theory doesn’t hold up. Lysine does not antagonize that amino acid in cats, has no effect on herpesvirus replication in lab studies, and multiple clinical trials in live cats showed no benefit. Some studies actually reported increased infection frequency and disease severity in cats receiving lysine. The review’s authors recommended stopping lysine supplementation entirely due to the complete lack of evidence for its effectiveness.
Complications to Watch For
Most URIs resolve without lasting problems, but some cats develop secondary issues. Conjunctivitis (eye inflammation) is common and usually clears with treatment, but herpesvirus can cause corneal ulcers that need specific attention. Signs include squinting, excessive tearing from one eye, or a visible cloudy spot on the eye’s surface.
Calicivirus, the other major cause of feline URIs, occasionally progresses to a severe systemic form that is fatal in roughly two-thirds of affected cats. This rare but serious version causes swelling of the head and limbs, crusting sores on the nose, eyes, ears, and footpads, and yellowing of the mouth or ears from liver damage. This is a veterinary emergency.
Chronic rhinosinusitis is another possible outcome, particularly in cats who had severe initial infections. These cats develop recurring bouts of sneezing, congestion, and nasal discharge that flare up during stress or immune suppression. Management is ongoing and focuses on keeping flare-ups mild through environmental stress reduction and prompt treatment when symptoms return.
Preventing Future Infections
The core feline vaccine (often called FVRCP) protects against herpesvirus, calicivirus, and panleukopenia. Kittens receive a series of shots every 2 to 4 weeks starting as early as 4 weeks of age and continuing through 16 to 18 weeks. A booster at 6 months of age is now recommended to close a potential gap in immunity that can occur as maternal antibodies fade. After that, injectable vaccines are boosted every 3 years, while intranasal versions are given annually.
Vaccination doesn’t guarantee a cat will never get a URI, but it significantly reduces the severity of illness. Cats who are already carriers of herpesvirus (which stays dormant in the body for life after initial infection) can still have flare-ups during periods of stress. Keeping your cat’s environment calm, minimizing major disruptions, and maintaining good nutrition are the best long-term strategies for reducing recurrence.