Feline herpesvirus (FHV-1) has no cure, but treatment can control symptoms, shorten flare-ups, and reduce how often they return. Nearly all cats that contract the virus become lifelong carriers, with the virus lying dormant and reactivating during periods of stress. Treatment focuses on antiviral medications, eye care, supportive home care, and long-term stress reduction.
What Feline Herpes Looks Like
FHV-1 causes upper respiratory and eye symptoms that can range from mild sniffles to severe illness, especially in young kittens. The most common signs include sneezing, nasal congestion, watery or mucus-filled discharge from the nose and eyes, and conjunctivitis (red, swollen eye tissue). Some cats develop fever, lethargy, and loss of appetite during an active flare.
Eye involvement is one of the hallmarks. The virus can cause characteristic branching ulcers on the cornea, which are considered a telltale sign of FHV-1 specifically. Chronic or recurring eye inflammation, including keratitis (inflammation of the cornea), is common in cats who experience repeated flare-ups over their lifetime.
Because early symptoms overlap with other infections like feline calicivirus, a vet may recommend PCR testing to confirm the diagnosis. PCR is highly sensitive and can detect very small amounts of viral material, making it more reliable than blood tests or clinical observation alone.
Antiviral Medications
Two antiviral drugs are the primary options for treating feline herpes. The first is an oral medication (famciclovir) given by mouth, typically every 8 to 12 hours and continued for about a week after symptoms resolve. It works systemically, meaning it targets the virus throughout the body. This is the go-to for moderate to severe flare-ups, particularly when eye disease is involved.
The second is a topical antiviral eye drop (trifluridine), applied directly to the affected eye. Topical antivirals are used when corneal ulcers or significant conjunctivitis are present. They require frequent application, often multiple times per day, which can be challenging with some cats. Your vet will determine which medication, or combination, fits your cat’s situation based on the severity and location of symptoms.
Antibiotics don’t treat the herpes virus itself, but vets sometimes prescribe them alongside antivirals. The reason: cats with active herpes flare-ups are vulnerable to secondary bacterial infections, which can worsen nasal and eye discharge and make recovery slower.
Supportive Care at Home
Much of what helps a cat through a herpes flare-up happens at home. Congestion is one of the biggest challenges because cats rely heavily on smell to find food appealing. A congested cat often refuses to eat, and prolonged appetite loss can become dangerous.
To loosen thick nasal secretions, try bringing your cat into a steamy bathroom for 10 to 15 minutes (run a hot shower with the door closed, but don’t put the cat in the water). Saline nose drops can also soften crusted discharge. Gently wipe away buildup from the nose and eyes several times a day using a warm, damp cloth. This keeps your cat comfortable and helps them breathe and see more easily.
Warming up wet food in the microwave for a few seconds can make it more aromatic and encourage eating. If your cat still refuses food for more than a day or two, contact your vet. Cats that won’t eat may need appetite-stimulating medication or, in severe cases, a temporary feeding tube. Keeping your cat well-hydrated is equally important. A water fountain or adding water to wet food can help.
Why L-Lysine Doesn’t Work
L-lysine supplements have been widely recommended for feline herpes for years, but the evidence is clear: they don’t help. A systematic review of the available research found no support for lysine supplementation at any level, from lab studies to clinical trials in actual cats. The supplement was originally thought to lower levels of an amino acid the virus needs to replicate, but lysine doesn’t actually affect that amino acid in cats.
More concerning, some studies found that cats receiving lysine supplements experienced more frequent infections and worse symptoms than cats that didn’t. The researchers recommended an immediate stop to lysine supplementation based on the complete absence of evidence for its effectiveness. If your cat is currently taking lysine, it’s worth discussing this with your vet.
Preventing Flare-Ups Long Term
Since virtually all infected cats carry the virus for life, the goal shifts from curing the infection to keeping flare-ups rare and mild. Stress is the single biggest trigger for reactivation. The virus stays dormant in nerve cells and reactivates when the immune system is suppressed, which stress reliably causes.
Practical steps to reduce stress include making household changes gradually rather than all at once, whether that’s rearranging furniture, introducing a new pet, or bringing a baby home. New animals and children should be introduced slowly and in controlled, low-pressure settings. Pheromone diffusers (synthetic versions of the calming scent cats produce naturally) can help ease anxiety in multi-cat homes or during transitions. For cats that are especially stress-prone, short-term anti-anxiety medication before a known stressor like travel or boarding is an option.
Keeping your cat’s overall health strong also matters. A consistent routine, a nutritionally complete diet, and staying current on vaccinations all support immune function. While the herpes vaccine doesn’t prevent infection in cats already carrying the virus, it can reduce the severity of symptoms during flare-ups. Cats in multi-cat households should ideally have separate food bowls, water sources, and litter boxes to minimize social stress and reduce viral transmission to uninfected cats.