Feline herpes (FHV-1) has no cure, but treatment can shorten flare-ups, relieve symptoms, and prevent complications. Most cats recover from acute episodes within two to three weeks with a combination of antiviral medication, supportive care at home, and management of secondary infections. Once a cat is infected, the virus stays dormant for life and can reactivate during periods of stress, so long-term management matters just as much as treating the immediate outbreak.
What Feline Herpes Looks Like
FHV-1 primarily attacks the upper respiratory tract and the eyes. You’ll typically see sneezing, nasal congestion, discharge from the nose and eyes, fever, and reduced appetite. Some cats develop corneal ulcers, which look like squinting, excessive tearing, or a cloudy spot on the eye. Kittens and cats with weakened immune systems tend to get hit hardest, sometimes refusing food entirely because they can’t smell it through the congestion.
A veterinarian can often diagnose feline herpes based on symptoms alone, but when confirmation is needed, PCR testing on nasal and throat swabs can detect even small amounts of the virus. This is especially useful for distinguishing FHV-1 from feline calicivirus, which causes similar respiratory symptoms but requires different management.
Antiviral Medications
The most widely used oral antiviral for feline herpes is famciclovir. It’s given three times a day and typically continued until about one week after symptoms fully resolve. Famciclovir doesn’t eliminate the virus from the body, but it slows viral replication enough to reduce the severity and duration of a flare-up. Your vet will determine the right dose based on your cat’s weight.
For eye involvement, topical antiviral drops or ointments are the standard approach. The two most effective options against FHV-1 strains need to be applied frequently, at least four to six times daily for two to three weeks. These drops can be irritating to the eye, so your cat may resist application, but consistency is important to prevent corneal damage. If your cat has a corneal ulcer or significant eye inflammation, your vet may also prescribe additional eye medications to manage pain and prevent scarring.
Clearing Nasal Congestion at Home
Congestion is one of the most distressing symptoms for cats with herpes because it blocks their sense of smell, which directly kills their appetite. Steam therapy is one of the simplest and most effective home treatments. Sit with your cat in a closed bathroom while running a hot shower. You’ll know there’s enough humidity when the mirror fogs up. This loosens dried secretions, rehydrates the airways, and makes breathing easier.
For cats with severe congestion, inexpensive saline nebulizers can be used at home. Run the nebulizer near your cat’s face for about 15 minutes, ideally every four to six hours. You can place your cat in a carrier and drape a towel over it to concentrate the mist. Between steam or nebulizer sessions, gently wipe away nasal discharge several times a day using a cotton ball or soft cloth dampened with saline solution. Applying a thin layer of barrier cream (like petroleum jelly) around the nostrils protects the skin from becoming raw and cracked.
Getting Your Cat to Eat
Food intake is extremely important during a feline herpes flare-up. Cats that stop eating for even a few days can develop serious liver problems, so maintaining nutrition is a genuine medical priority, not just a comfort measure. Because congestion dulls their sense of smell, try warming wet food in the microwave for a few seconds to intensify its aroma. Strong-smelling foods like fish-based varieties often work best.
If your cat refuses food entirely for more than 24 to 48 hours, your vet may recommend a feeding tube. Modern silicone tubes placed through the side of the neck are well tolerated and allow you to deliver food and medications without stressing your cat’s sore nose and throat. Cats with severe symptoms may also need IV fluids to correct dehydration and electrolyte imbalances from reduced eating and excess drooling.
Managing Secondary Bacterial Infections
Feline herpes is a virus, so antibiotics don’t treat the infection itself. However, the virus damages the lining of the respiratory tract, creating an opening for bacteria to move in. When nasal discharge turns thick, yellow, or green, or when a fever persists despite antiviral treatment, a secondary bacterial infection is likely. Your vet will prescribe antibiotics in these cases to prevent the infection from worsening into pneumonia or chronic sinusitis.
L-Lysine Does Not Work
L-lysine supplements have been marketed for years as a way to suppress feline herpes outbreaks. The theory was that lysine would lower levels of another amino acid the virus needs to replicate. A systematic review of the evidence found this doesn’t hold up. Lysine has no antiviral properties against FHV-1, does not reduce arginine levels in cats the way proponents claimed, and showed no effect on viral replication in lab studies. More concerning, some clinical studies found that cats receiving lysine supplementation actually experienced more frequent infections and worse symptoms. Researchers have recommended an immediate stop to lysine supplementation based on the complete lack of evidence for its effectiveness.
Preventing Flare-Ups
Since virtually all cats that recover from FHV-1 carry the virus for life, preventing stress-triggered reactivation is the core of long-term management. Common triggers include moving to a new home, introducing a new pet or family member, boarding, surgery, or any significant disruption to routine.
Make changes to your cat’s environment gradually when possible. Introduce new animals or children slowly and in controlled settings. Synthetic pheromone diffusers, which release calming chemicals that mimic natural feline facial pheromones, can help reduce background anxiety. In cases where a known stressor is unavoidable, such as a move or a veterinary procedure, your vet may recommend short-term anti-anxiety medication to reduce the chance of a flare-up. Keeping your cat’s living space clean, quiet, and predictable goes a long way toward keeping the virus dormant.
The Role of Vaccination
The standard FVRCP vaccine given to kittens and adult cats includes protection against FHV-1. It does not prevent infection entirely. Vaccinated cats that encounter the virus will still become infected and can still shed it to other cats. What the vaccine does is significantly reduce the severity of illness. In challenge studies, vaccinated kittens had less severe clinical signs and shed substantially less virus compared to unvaccinated kittens, which could reduce transmission to other cats in the household.
Combining an intranasal vaccine with a standard injectable vaccine has shown even better results than the injectable alone. For cats already carrying the virus, staying current on boosters may help reduce the severity of future reactivation episodes, though it won’t eliminate them. Vaccination is most valuable as a preventive step before a cat is ever exposed, which is one reason kittens are vaccinated early in their core series.