Calicivirus in Cats: Symptoms, Spread, and Care
Feline calicivirus (FCV) is a highly contagious virus that causes upper respiratory infection and painful mouth ulcers in cats. Most cats recover with supportive care, though some develop long-term mouth inflammation (stomatitis) and, in rare cases, a severe systemic form. There is no way to clear the virus from the body entirely, so care focuses on managing symptoms and supporting recovery under veterinary guidance.
A cat resting comfortably at home.
What Is Calicivirus in Cats?
Calicivirus in cats is a common viral infection caused by feline calicivirus (FCV), one of the leading causes of upper respiratory disease and oral disease in cats. It spreads easily in multi-cat settings such as shelters, catteries, and foster homes, and it is a frequent reason for sneezing, nasal discharge, and mouth ulcers.
FCV is a different virus from feline herpesvirus, even though both are grouped under the "cat flu" umbrella. It is also entirely separate from Feline Infectious Peritonitis ("FIP"), which is caused by a coronavirus and treated very differently. If you are researching FIP instead, you can read our plain English guide to FIP in cats.
FCV mutates readily, which is why so many strains circulate and why the severity of illness varies widely from one cat to the next. Some cats shed the virus for weeks or months after their signs fade, and a smaller number become long-term carriers.
What Are the Symptoms of Feline Calicivirus?
The most common feline calicivirus symptoms are sneezing, nasal and eye discharge, and ulcers on the tongue, gums, or hard palate that cause drooling and reluctance to eat. Signs usually appear within 2 to 6 days of exposure and range from mild to severe depending on the cat and the strain.
Oral ulcers are one of the most distinctive features of FCV. Cats with mouth ulcers may paw at the face, drop food, drool, or stop eating altogether. If you are seeing these signs, our guide on cat drooling and mouth ulcers explains when FCV is the likely cause.
Mild to Moderate Respiratory Signs
Many cats experience a self-limiting cat respiratory infection with sneezing, a runny nose, watery eyes, mild fever, and low energy. These cases often improve within 1 to 2 weeks with supportive care, rest, and good nutrition.
Oral Disease and Chronic Stomatitis
Some cats develop severe, painful inflammation of the mouth and gums called stomatitis, which can become chronic. This condition causes lasting mouth pain, bad breath, weight loss, and difficulty eating. You can learn more in our article on feline calicivirus and chronic mouth pain.
Limping Syndrome
A subset of cats, especially kittens, develop transient lameness or joint pain, sometimes alongside fever. This "limping syndrome" is usually short-lived and resolves as the infection settles.
Virulent Systemic FCV (VS-FCV)
Rarely, a severe strain known as virulent systemic feline calicivirus causes high fever, swelling of the face and limbs, jaundice, and organ involvement, and it can be life-threatening. Because this form behaves so differently, our explainer on the so-called Khaleesi virus covers VS-FCV in detail.
How Does Calicivirus Spread Between Cats?
Feline calicivirus spreads through direct contact with saliva, nasal secretions, and eye discharge from an infected cat, and through shared bowls, litter boxes, bedding, and human hands. It is highly contagious and survives in the environment for up to a month on surfaces, which makes multi-cat households and shelters high-risk settings.
Sneezing can aerosolize the virus over short distances, so cats housed close together are easily exposed. Carrier cats can shed FCV even when they look healthy, which is one reason the virus is so difficult to keep out of group environments.
Good hygiene reduces the risk considerably: isolate sick cats, wash hands between cats, and disinfect shared items with a product effective against non-enveloped viruses. For a full breakdown, see our U.S. owner's guide to how feline calicivirus spreads.
How Is Calicivirus in Cats Diagnosed?
A veterinarian diagnoses calicivirus based on a physical exam, the cat's history, and the classic combination of respiratory signs and oral ulcers, sometimes confirmed with a PCR swab from the mouth or nose. Testing helps distinguish FCV from feline herpesvirus and from other causes of mouth disease.
Because mouth ulcers and stomatitis can have more than one cause, your veterinarian may also check for other dental and immune conditions. Our article on whether calicivirus is behind stomatitis explains how that assessment usually works.
Tell your veterinarian about any other cats in the home, recent adoptions, or shelter exposure, since this context shapes both diagnosis and infection control.
What Is the Treatment for Calicivirus in Cats?
Calicivirus treatment for cats centers on supportive care, because no treatment removes the virus from the body. The goals are to control symptoms, manage pain, keep the cat eating and hydrated, and treat any secondary bacterial infection, all under veterinary supervision.
Supportive measures often include:
Pain relief and anti-inflammatory support for mouth ulcers, prescribed by your veterinarian
Nutritional support with soft, warmed, palatable food to encourage eating
Fluids to maintain hydration
Antibiotics only when a secondary bacterial infection is present, since antibiotics do not act on the virus itself
A calm, low-stress environment, because stress can worsen flare-ups
For ongoing oral FCV disease such as stomatitis and gingivitis, an antiviral option in the CureFIP catalog is EIDD-1931 Oral Capsules, positioned under the CaliciX line for FCV. The listed dose is 1 capsule (15 mg) per 2.5 kg of body weight, every 12 hours, with 60 capsules per bottle and a standard course of 60 days. This product is priced at $39.00.
Product | Dosing (per catalog) | Course | Price |
EIDD-1931 Oral Capsules (CaliciX line, FCV) | 1 capsule (15 mg) per 2.5 kg, every 12 hours | 60 days (standard) | $39.00 |
Important safety notes from the catalog: EIDD-1931 is not for ocular or neurological cases, or for cats that are not eating or defecating, and it is teratogenic, so it must not be used in pregnant or lactating queens. Your veterinarian should confirm whether any antiviral is appropriate for your cat and set the exact plan. For a balanced look at what does and does not help, read our guide on feline calicivirus treatment.
It is worth being clear about scope: EIDD-1931 is also one of the two antivirals used in CureFIP's oral FIP protocol, but FIP and FCV are separate diseases with separate plans. The FCV-positioned use above is specifically for oral calicivirus disease, not for FIP.
Can Cats Recover from Calicivirus?
Most cats recover from the acute phase of feline calicivirus within 1 to 2 weeks with good supportive care, though the virus can remain in the body and some cats become carriers or develop chronic stomatitis. Recovery depends on the strain, the cat's age and immune status, and how quickly care begins.
Kittens, senior cats, and cats with weakened immune systems tend to have a harder time and need closer monitoring. Cats with chronic oral disease may need long-term management rather than a single course of treatment.
For a realistic picture of what to expect week by week, see our article on whether cats recover from feline calicivirus.
How Can You Prevent Calicivirus in Cats?
Prevention relies on vaccination, hygiene, and reducing exposure, since FCV is so contagious and persistent in the environment. Core feline vaccines include FCV and reduce the severity of illness, though they do not prevent every strain because the virus mutates.
Practical steps that lower risk include:
Keep core vaccinations current on your veterinarian's schedule.
Quarantine new or sick cats before introducing them to the household.
Wash hands and change or clean items between cats.
Disinfect bowls, litter boxes, and bedding regularly.
Reduce stress and overcrowding, which both increase flare-ups and shedding.
CureFIP has supported more than 100,000 cats since 2019 across its antiviral programs, and that experience is built on one principle: clear information and veterinary partnership lead to better outcomes.
FAQ
Is feline calicivirus contagious to humans?
No. Feline calicivirus does not infect humans. It spreads between cats through saliva, nasal and eye secretions, and contaminated surfaces, so your main job is to prevent cat-to-cat spread with good hygiene and isolation of sick cats.
How long does calicivirus last in cats?
The acute illness usually lasts 1 to 2 weeks in otherwise healthy cats. However, some cats shed the virus for weeks or months, and a subset become long-term carriers or develop chronic stomatitis that needs ongoing management.
What is the difference between calicivirus and herpesvirus in cats?
Both cause upper respiratory signs, but feline calicivirus is especially associated with mouth ulcers and sometimes limping, while feline herpesvirus is more associated with eye disease and corneal ulcers. They are different viruses, so your veterinarian may use a PCR test to tell them apart and tailor care.
Do antibiotics treat calicivirus in cats?
No. Antibiotics do not act on the virus itself. A veterinarian may still prescribe them when a secondary bacterial infection is present, alongside supportive care for pain, hydration, and nutrition.
Can calicivirus come back after a cat recovers?
Yes. Because the virus can persist in the body, recovered cats may experience flare-ups, often triggered by stress, and carrier cats can shed the virus again. Keeping stress low and vaccinations current helps reduce recurrence.
If your cat is showing signs of calicivirus, the most important next step is a conversation with your veterinarian about diagnosis and a care plan that fits your cat. To explore the antiviral options available and get support from a team that works with these cases every day, visit CureFIP to learn more. Every treatment decision should be made with your veterinarian, who knows your cat best.
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