Feline Herpesvirus Symptoms in Cats: A Home-Care Guide

Feline herpesvirus (FHV-1) is one of the most common causes of upper respiratory infection in cats, and its main symptoms are sneezing, runny eyes and nose, squinting, and conjunctivitis. It is a lifelong infection, so care focuses on reducing stress-triggered flare-ups and supporting your cat through them, not on eliminating the virus. Antivirals such as famciclovir may be prescribed by your veterinarian, while antibiotics only address secondary bacterial infections, not the virus itself.

What is feline herpesvirus (FHV-1) in cats?

Feline herpesvirus (FHV-1) is a highly contagious virus and a leading cause of upper respiratory infection in cats, sometimes called "cat flu" or feline viral rhinotracheitis. It mainly affects the eyes and the upper airways, and most infected cats carry it for life.

Once a cat is infected, the virus stays in the body and settles into a quiet, latent state. During times of stress or illness, it can reactivate and cause a flare-up, which is why many Pawrents see symptoms come and go over the years.

FHV-1 is extremely common in the general cat population in the United States, especially in shelters, catteries, and multi-cat homes. Kittens and cats with weaker immune systems tend to show the most obvious signs.

What are the symptoms of feline herpesvirus in cats?

The most common feline herpesvirus symptoms in cats are sneezing, clear or colored nasal discharge, watery or gooey eye discharge, squinting, and red, swollen eyes (conjunctivitis). Many cats also run a mild fever, feel tired, and eat less during a flare.

Because FHV-1 targets the eyes and nose, the signs often cluster together. Here is what to watch for.

Eye signs

• Watery, red, or squinting eyes

• Thick or crusty eye discharge

• Conjunctivitis (inflammation of the pink tissue around the eye)

• In more serious cases, corneal ulcers, which can cause pain and cloudiness

Respiratory signs

• Frequent sneezing, sometimes in bursts

• Clear or yellow-green nasal discharge

• Congestion and noisy breathing

• Reduced appetite, often because a stuffy nose dulls the sense of smell

Other signs

• Mild fever and low energy

• Drooling or mouth ulcers in some cats

• Recurrent flare-ups that return during stressful periods

If your cat stops eating for more than a day, struggles to breathe, or develops a painful or cloudy eye, treat that as urgent and contact your veterinarian right away.

How can I tell FHV-1 apart from calicivirus?

FHV-1 and feline calicivirus (FCV) are two different viruses that both cause upper respiratory signs, but FHV-1 leans toward heavy eye involvement and sneezing, while calicivirus leans toward mouth ulcers, gingivitis, and oral pain. Only your veterinarian can confirm which virus is present, since the two often look similar early on and can even occur together.

A quick side-by-side can help you understand what you are seeing at home.

Feature	Feline herpesvirus (FHV-1)	Feline calicivirus (FCV)
Main target	Eyes and upper airways	Mouth and upper airways
Hallmark signs	Sneezing, eye discharge, squinting, conjunctivitis	Mouth ulcers, gingivitis, stomatitis, drooling
Course	Lifelong, flares with stress	Can clear, but some cats become carriers
Antiviral your vet may use	Famciclovir	A separate antiviral approach

If you suspect calicivirus rather than herpesvirus, you can learn the early warning signs in this guide to feline calicivirus symptoms, and read a fuller overview in the complete calicivirus owner guide for the USA. Getting the right diagnosis matters, because the two viruses are managed differently.

What triggers a feline herpesvirus flare-up?

A feline herpesvirus flare-up is most often triggered by stress, which suppresses the immune system and lets the latent virus reactivate. Common triggers include moving to a new home, boarding, new pets or people, changes in routine, and other illnesses.

Because the virus never fully leaves the body, your goal is to keep these triggers to a minimum. Recognizing your cat's personal stressors is one of the most useful things you can do.

Common flare-up triggers include:

• Rehoming, travel, or boarding

• A new cat, dog, baby, or houseguest

• Overcrowded or noisy environments

• Other infections or illnesses

• Surgery or hospitalization

• Sudden changes in diet or daily routine

Many Pawrents notice a clear pattern once they start tracking flares. A simple note on your phone about when symptoms appear can reveal the trigger.

How do I support a cat with feline herpesvirus at home?

Supporting a cat with feline herpesvirus at home centers on reducing stress, keeping the eyes and nose clean, encouraging eating and hydration, and following your veterinarian's plan. Good home care shortens the discomfort of a flare and helps prevent secondary bacterial infections.

Here is a practical, step-by-step approach you can follow during a flare.

1. Gently clean the eyes and nose. Use a soft cloth or cotton pad dampened with warm water to wipe away discharge several times a day. Always wipe from the inner corner outward, and use a fresh section for each eye.

2. Open up the airways with humidity. Let your cat sit with you in a steamy bathroom for 10 to 15 minutes, or run a humidifier nearby. Moist air helps loosen congestion.

3. Make food easy and appealing. Warm the food slightly to boost its aroma, and offer strong-smelling wet food. A congested cat that cannot smell well may simply stop eating.

4. Keep water fresh and everywhere. Encourage drinking with clean bowls or a pet fountain to prevent dehydration during a flare.

5. Lower the stress in the home. Provide quiet resting spots, keep routines steady, and consider a feline pheromone diffuser to help your cat feel secure.

6. Follow your veterinarian's instructions exactly. If your veterinarian prescribes medication, give it as directed and finish the full course.

Never give human cold medicines or human eye drops to your cat, because many are toxic to cats. When in doubt, talk with your veterinarian first.

Do antibiotics treat feline herpesvirus?

Antibiotics do not treat feline herpesvirus itself, because FHV-1 is a virus and antibiotics only work against bacteria. Your veterinarian may still prescribe an antibiotic if a secondary bacterial infection develops on top of the viral flare, such as a bacterial complication in the nose or eyes.

For the virus itself, veterinarians turn to antiviral medicine instead. Famciclovir is an oral antiviral that a veterinarian may prescribe to help manage FHV-1 flare-ups in cats.

Many Pawrents also ask about supportive supplements. L-lysine has been used for years, though the evidence is mixed, so discuss whether it fits your cat's situation with your veterinarian rather than starting it on your own. You can read more about antiviral options in this overview of the best antiviral for feline herpesvirus in cats.

Can feline herpesvirus be prevented?

Feline herpesvirus cannot be fully prevented once a cat is exposed, but vaccination, stress reduction, and good hygiene greatly lower the risk of infection and reduce how often and how severely flare-ups occur. The core feline vaccine (FVRCP) includes protection that helps limit the severity of FHV-1 disease.

Prevention is really about two goals: reducing new exposure and reducing flare-ups in cats that already carry the virus.

Steps that lower risk

• Keep your cat's FVRCP vaccinations current, as advised by your veterinarian

• Isolate new or sick cats before introducing them to your household

• Wash your hands and clean shared bowls, bedding, and litter boxes regularly

• Avoid overcrowding in multi-cat homes

• Keep stress low with predictable routines and enough space, perches, and hiding spots

FHV-1 spreads through direct contact and shared surfaces, so hygiene in multi-cat homes makes a real difference. A calm, well-managed environment is one of the strongest tools you have.

When should I take my cat to the veterinarian?

You should take your cat to the veterinarian if symptoms last more than a few days, if your cat stops eating, if breathing becomes labored, or if an eye looks painful, cloudy, or has a visible ulcer. Kittens, senior cats, and cats with other health problems need prompt attention because they can decline quickly.

Call your veterinarian promptly if you notice any of the following:

• No eating for more than 24 hours

• Labored, open-mouth, or noisy breathing

• A squinting, cloudy, or clearly painful eye

• Thick green or bloody nasal discharge

• Lethargy, dehydration, or a flare that keeps worsening

Early veterinary care helps prevent complications like corneal damage and secondary infections. Your veterinarian can confirm the diagnosis and build a plan matched to your cat.

FAQ

Is feline herpesvirus contagious to humans or other pets?

Feline herpesvirus (FHV-1) is not contagious to humans or dogs. It spreads between cats through direct contact and shared items like bowls and bedding, so isolate an actively sneezing cat from other cats in the home and wash your hands after handling.

Does feline herpesvirus ever go away completely?

No. Feline herpesvirus stays in your cat's body for life and settles into a latent state between flare-ups. The good news is that many cats live full, comfortable lives when flares are managed with stress reduction, supportive care, and guidance from a veterinarian.

Can stress really cause a herpesvirus flare-up?

Yes. Stress is the single most common trigger for a feline herpesvirus flare-up because it weakens the immune system and lets the latent virus reactivate. Moving, boarding, new pets, and changes in routine are frequent culprits, so keeping life predictable helps.

Is famciclovir the same as the antiviral used for FIP or calicivirus?

No. Famciclovir is an antiviral a veterinarian may prescribe specifically for feline herpesvirus, while Feline Infectious Peritonitis (FIP) and Feline Calicivirus (FCV) are managed with a different antiviral compound. These are distinct viruses, so the treatment approaches are not interchangeable, and your veterinarian will match the medicine to the diagnosis.

How long does a herpesvirus flare-up usually last?

Most uncomplicated FHV-1 flare-ups improve within one to two weeks with supportive care. If symptoms drag on longer, worsen, or involve the eyes or appetite, contact your veterinarian, since a secondary bacterial infection or corneal problem may need treatment.

If your cat is showing signs of a flare, calm, consistent home care and a good relationship with your veterinarian go a long way. To explore feline antiviral topics further and get support, you are welcome to reach out to the MolnuFIP team and to talk with your own veterinarian about the plan that fits your cat best.