Can FIP in Cats Be Cured? What the Evidence Shows

Key takeaway: Feline Infectious Peritonitis (FIP) was once considered almost always fatal, but that has changed. GS-441524 antiviral treatment now brings many cats to lasting remission, with a 92% success rate reported by UC Davis (Pedersen, 2019) for monotherapy. With a complete 84-day protocol under veterinary supervision, a diagnosis of FIP is no longer the end of the story.

Below we explain what remission means, how treatment works across the four forms of FIP, what the data does and does not show, and what a real course of treatment looks like.

Can FIP in cats actually be treated successfully?

Yes. FIP can be treated successfully in the great majority of cats with GS-441524, the antiviral at the core of modern FIP treatment. UC Davis reported a 92% success rate for GS-441524 monotherapy (Pedersen, 2019), and across the CureFIP network more than 100,000 cats have been treated since 2019.

This is a profound shift. For decades, FIP was a disease vets could only manage for comfort. The arrival of GS-441524 changed the outlook for cats whose owners pursue a full, supervised course.

We are careful with language here. We talk about remission and success rates, not guarantees, because outcomes depend on the form of FIP, how early treatment starts, dosing accuracy, and your veterinarian's monitoring.

What does "remission" mean in FIP treatment?

Remission in FIP means the virus is suppressed, clinical signs resolve, and bloodwork returns toward normal, with the cat staying healthy after treatment ends. A standard course runs 84 days (12 weeks), followed by an observation period your veterinarian will guide.

Remission is the honest, evidence-based way to describe a good outcome. A cat that completes the protocol, recovers, and remains well through the post-treatment watch period is considered to be in remission.

Most relapses, when they happen, occur within the weeks after treatment stops. That is why finishing the full 84 days and monitoring afterward matters so much. You can read more about what to expect in our GS-441524 treatment timeline guide.

Why was FIP once considered untreatable?

FIP develops when a common feline coronavirus mutates inside an individual cat and triggers an aggressive immune response. Before targeted antivirals, there was no medicine that could stop the virus, so the disease was almost always fatal.

The breakthrough was GS-441524, a nucleoside analogue that blocks the virus from replicating. Once vets had a drug that addressed the cause rather than only the symptoms, survival became a realistic goal.

Recognising the disease early gives treatment the best chance. If you are still at the diagnosis stage, our overview of 12 early warning symptoms of FIP explains the signs that should prompt a veterinary visit.

Does the type of FIP affect whether it can be treated?

Yes. FIP takes four forms, wet, dry, ocular, and neurological, and each shapes the treatment plan and the dose. The form is also why your veterinarian sets the dosing per kilogram rather than using a single fixed amount.

The four forms below mirror the four-row dosing structure of the CureFIP injectable protocol, so symptoms and dosing stay aligned.

Wet (effusive) FIP

Wet FIP causes fluid to build up in the abdomen or chest, leading to a swollen belly or laboured breathing. It is often the fastest-moving form, so prompt veterinary care matters.

For the CureFIP injectable protocol, wet FIP is dosed at 6 mg/kg, given as one subcutaneous injection per day, every day, for 84 days.

Dry (non-effusive) FIP

Dry FIP produces little or no fluid and instead causes inflammatory lesions in organs, often with vague signs such as weight loss, fever, and lethargy. It can be harder to diagnose because the signs are subtle.

For the CureFIP injectable protocol, dry FIP is dosed at 8 mg/kg, given as one subcutaneous injection per day, every day, for 84 days.

Ocular FIP

Ocular FIP affects the eyes, causing colour changes, cloudiness, or inflammation, and can appear alongside other forms. Because the eye is harder for medicine to reach, it calls for a higher dose.

For the CureFIP injectable protocol, ocular FIP is dosed at 10 mg/kg, given as one subcutaneous injection per day, every day, for 84 days.

Neurological FIP

Neurological FIP involves the brain and spinal cord, causing signs such as wobbliness, seizures, or behaviour changes. Like ocular FIP, it requires a higher dose to cross into the affected tissue.

For the CureFIP injectable protocol, neurological FIP is dosed at 10 mg/kg, given as one subcutaneous injection per day, every day, for 84 days.

What is the dosing for each form of FIP?

The CureFIP injectable protocol doses GS-441524 by the form of FIP, given once daily by subcutaneous injection for 84 days. Your veterinarian sets the exact volume based on your cat's current weight.

FIP form	Daily dose	Schedule	Duration
Wet / effusive	6 mg/kg	1 SC injection per day	84 days
Dry / non-effusive	8 mg/kg	1 SC injection per day	84 days
Ocular	10 mg/kg	1 SC injection per day	84 days
Neurological	10 mg/kg	1 SC injection per day	84 days

Dosing reference: Pedersen et al., UC Davis (PMC6435921). Always confirm the exact dose and volume with your veterinarian, who will adjust as your cat regains weight.

Which CureFIP products are used to treat FIP?

CureFIP offers GS-441524 injectables in three strengths plus a dual antiviral oral capsule. The choice depends on the form of FIP, your cat's weight, and your veterinarian's plan.

Product	Strength	Volume	Price
CureFIP™ GS-441524 Injectable 20mg/ml	20 mg/ml	8ml, 10ml	€79.00
CureFIP™ GS-441524 Injectable 30mg/ml	30 mg/ml	8ml, 10ml	€89.00
Cure FIP Antiviral 40mg/ml	40 mg/ml	8ml, 10ml	€119.00
CURE FIP™ Dual Antiviral Oral Capsules	dose by weight (see below)	n/a	€179.00

All three injectables follow the same per-form dosing in the table above. Higher concentrations simply mean a smaller injection volume for heavier cats, which your veterinarian will calculate.

How do the oral dual antiviral capsules work?

The CURE FIP™ Dual Antiviral Oral Capsules combine GS-441524 with EIDD-1931 and are dosed by weight band, one capsule per day, for a recommended 12 weeks. This oral dual route is positioned for wet and dry FIP.

Weight band	Per capsule (daily)
Under 2.5 kg	GS-441524 25 mg + EIDD-1931 5 mg
2.5 to 5 kg	GS-441524 35 mg + EIDD-1931 8 mg
Over 5 kg	GS-441524 50 mg + EIDD-1931 12 mg

Some regions note the oral dual capsules are not recommended once ocular or neurological signs are present, or if the cat cannot eat or defecate. Your veterinarian will decide whether the injectable or oral route suits your cat.

The rationale for combining two antivirals is covered in our explainer on how dual antiviral therapy is changing FIP treatment, and in more clinical depth in our piece on dual nucleoside analogue therapy.

What success rates does the evidence show?

The evidence shows two product-matched figures that should never be blended. GS-441524 monotherapy reported a 92% success rate at UC Davis (Pedersen, 2019), while dual antiviral therapy with GS-441524 plus EIDD-1931 reported 78.3% remission in cats that had already relapsed (Li and Cheah, 2025).

Treatment approach	Reported outcome	Source
GS-441524 monotherapy (injectables)	92% success rate	UC Davis (Pedersen, 2019)
Dual antiviral (GS-441524 + EIDD-1931)	78.3% remission	Li and Cheah, 2025

These numbers describe different groups of cats and different protocols, which is why we keep them separate. The 78.3% figure is especially meaningful because it comes from cats that had already relapsed, a harder-to-treat population, as detailed in our write-up of the CureFIP dual antiviral study results.

How long does FIP treatment take?

A standard course runs 84 days (12 weeks) of daily treatment under veterinary supervision, followed by an observation period. Treatment is not stopped early just because the cat looks better.

Throughout the 84 days, your veterinarian will track recovery with regular bloodwork, watching markers return toward normal. Understanding those results helps you follow progress, which is why we created a guide to cat bloodwork during FIP treatment.

Consistency is the single most important factor you control. Daily dosing, accurate weight-based dose adjustments, and finishing the full protocol all support the best chance of remission. Our FIP survival tips cover the day-to-day habits that help.

What about relapse after treatment ends?

Most cats that complete the full 84-day protocol and pass their post-treatment observation stay in lasting remission. When relapse happens, it usually appears within the weeks after treatment stops, which is why monitoring continues after the final dose.

If signs return, your veterinarian may extend treatment or adjust the approach. The 78.3% remission reported by Li and Cheah (2025) for dual antiviral therapy specifically involved previously relapsed cats, showing that relapse is not the end of the road.

FAQ

Can FIP in cats be cured?

FIP can now be brought to lasting remission in the majority of cats with GS-441524 antiviral treatment, where it was once almost always fatal. UC Davis reported a 92% success rate for monotherapy (Pedersen, 2019), though outcomes depend on the form of FIP, early diagnosis, and a complete 84-day course under veterinary supervision.

How long is the FIP treatment protocol?

The standard FIP treatment protocol is 84 days (12 weeks) of daily GS-441524, followed by an observation period your veterinarian will guide. Treatment should not be stopped early, even when your cat appears fully recovered.

Does the form of FIP change the dose?

Yes. The CureFIP injectable protocol doses by form: wet 6 mg/kg, dry 8 mg/kg, ocular 10 mg/kg, and neurological 10 mg/kg, given once daily by subcutaneous injection. Your veterinarian sets the exact volume based on your cat's current weight.

What is the difference between the injectable and the oral dual antiviral?

The injectables deliver GS-441524 alone and are dosed by FIP form, while the CURE FIP™ Dual Antiviral Oral Capsules combine GS-441524 with EIDD-1931 and are dosed by weight band, positioned for wet and dry FIP. The oral dual capsules may not be recommended once ocular or neurological signs are present, so your veterinarian will choose the right route.

Can a cat that relapsed still reach remission?

Yes. Dual antiviral therapy with GS-441524 plus EIDD-1931 reported 78.3% remission in cats that had already relapsed (Li and Cheah, 2025), showing that relapse does not mean treatment has failed. Your veterinarian can advise on extending or adjusting the plan.

If your cat has been diagnosed with FIP, you do not have to navigate it alone. Explore the FIP treatment options at CureFIP and talk with our team or your own veterinarian about the plan that fits your cat best. Every medical decision should be made together with the vet who knows your cat.