Best Treatment for FIP in Cats in Australia Explained

Key takeaway: The most effective treatment for Feline Infectious Peritonitis (FIP) in Australia is a course of direct-acting antiviral therapy given under veterinary supervision, not antibiotics or steroids alone. MolnuFIP uses EIDD-1931, the active antiviral metabolite of molnupiravir, at 15 mg per capsule, and evidence shows antiviral treatment can drive many cats into lasting remission when started early and paired with good supportive care.

If your cat has just been diagnosed, you are likely reading fast and feeling scared. Here is what the current research actually shows, what your realistic options are in Australia and New Zealand, and the specific questions to bring to your veterinarian.

A cat resting comfortably at home.

What is the best treatment for Feline Infectious Peritonitis (FIP) in cats?

The best treatment for Feline Infectious Peritonitis (FIP) is a sustained course of a direct-acting antiviral, given daily for up to 60 days under veterinary guidance, alongside supportive care. Antivirals target the virus itself, which is why they changed the outlook for a disease that was once considered fatal in nearly every case.

MolnuFIP for FIP contains EIDD-1931, 15 mg per capsule. EIDD-1931 is the active antiviral metabolite of molnupiravir, not the human capsule, and it works by disrupting how the FIP virus copies its genetic material.

Antibiotics do not treat FIP, because FIP is caused by a mutated feline coronavirus, not by bacteria. Steroids may reduce inflammation and ease symptoms for a short time, but they do not stop viral replication, so they are supportive rather than curative in role.

For a broader primer on the disease before you choose a treatment, this complete 2026 guide to FIP in cats is a useful starting point.

Which forms of FIP can be treated, and which need extra care?

Feline Infectious Peritonitis (FIP) has four distinct forms, and the treatment approach depends on which form your cat has. The four forms are wet (effusive), dry (non-effusive), neurological, and ocular.

MolnuFIP for FIP is indicated for wet (effusive) FIP, dry (non-effusive) FIP, and mixed or transitional presentations. It is not recommended for ocular FIP or neurological FIP.

Here is how the forms differ:

• Wet (effusive) FIP: fluid builds up in the abdomen or chest, causing a swollen belly or laboured breathing.

• Dry (non-effusive) FIP: little or no fluid, with weight loss, fever, and organ involvement instead.

• Neurological FIP: nervous-system signs such as seizures, head tilt, loss of balance, paralysis, and disorientation.

• Ocular FIP: eye-specific signs such as iris colour change, cloudiness, inflammation inside the eye (uveitis), and vision loss from ocular lesions.

If your cat shows neurological or ocular signs, talk with your veterinarian about an appropriate plan, because those forms are not indications for this product. A visual walkthrough of every form is available in this guide to FIP symptoms across all four forms.

How does EIDD-1931 compare to GS-441524 for FIP?

EIDD-1931 and GS-441524 are two separate antiviral compounds, and studies report that EIDD-1931 is roughly 7.3 times more potent than GS-441524 against feline coronavirus in laboratory testing. Higher potency means a smaller amount of the active molecule is needed to suppress the same amount of virus.

GS-441524 has been the compound most Australian Pawrents heard about first, and it remains a widely discussed option. MolnuFIP does not contain GS-441524; its active ingredient is EIDD-1931.

Compound	Role in FIP care	Relative potency
EIDD-1931 (in MolnuFIP)	Active antiviral metabolite of molnupiravir	Reference compound
GS-441524	Separate antiviral compound, discussed as an alternative	About 7.3x less potent than EIDD-1931

If you are still researching the GS-441524 route as well, this overview on sourcing legitimate GS-441524 explains what to look for, though supply and rules differ by country.

How is MolnuFIP dosed for FIP in cats?

The general dosing reference for MolnuFIP for FIP is 1 capsule (EIDD-1931, 15 mg) every 12 hours per 2.5 kg of body weight, continued for up to 60 days under veterinary guidance. The twice-daily rhythm matters, because keeping the antiviral at a steady level in the body helps suppress the virus around the clock.

Your veterinarian should confirm the exact dose for your individual cat, weigh your cat regularly, and adjust as your cat gains weight during recovery. Dosing and monitoring belong with your veterinarian throughout the whole course.

Body weight	General guide	Duration
Per 2.5 kg	1 capsule (15 mg) every 12 hours	Up to 60 days

Do not stop early just because your cat looks better. Many relapses trace back to a course that was cut short, so completing the full period your veterinarian sets is one of the most important things you can do.

Can FIP in cats go into remission?

Yes, Feline Infectious Peritonitis (FIP) can go into remission, and many Pawrents report meaningful improvement within the first one to two weeks of antiviral treatment. Common early signs of response include a returning appetite, a falling temperature, more energy, and gradual reabsorption of fluid in wet FIP cases.

Remission means the disease is controlled and the cat is well, not that the virus is instantly gone. This is why the full treatment course and a monitoring window afterwards both matter.

Every cat responds differently, and outcomes depend on the form of FIP, how early treatment starts, and the quality of supportive care. For a deeper, evidence-led look at outcomes, read what the evidence shows about FIP recovery.

What supportive care helps alongside antiviral treatment?

Supportive care helps your cat stay strong while the antiviral does its work, and it can make a real difference to comfort and recovery. The goal is to keep your cat eating, hydrated, and calm while the virus is brought under control.

Practical supportive steps include:

1. Offer warm, highly palatable food to rebuild appetite and body weight.

2. Keep fresh water available and watch for dehydration.

3. Provide a quiet, warm, low-stress resting space.

4. Give every dose on schedule and keep a simple daily log of weight, appetite, and energy.

5. Attend all recheck appointments and follow-up bloodwork your veterinarian requests.

Your veterinarian may also recommend liver or kidney support and regular blood tests to track organ health during treatment. These are decisions to make together with your veterinary team.

How much does FIP treatment cost in Australia?

FIP treatment cost in Australia varies with your cat's weight, the form of Feline Infectious Peritonitis (FIP), and the length of the course, because heavier cats need more capsules and longer courses cost more. There is no single fixed price that applies to every cat.

The main drivers of total cost are:

• Your cat's body weight, which sets the daily number of capsules.

• The total treatment duration, up to 60 days.

• Any supportive medications, fluids, or diagnostic tests your veterinarian recommends.

• Follow-up bloodwork and recheck visits.

Because these factors differ for every cat, ask your veterinarian and the MolnuFIP team for a plan built around your cat's actual weight and diagnosis rather than a generic figure.

Why choose an evidence-led antiviral over waiting or antibiotics?

Choosing a direct-acting antiviral early gives your cat the best evidence-based chance, because Feline Infectious Peritonitis (FIP) is driven by a virus that antibiotics cannot touch. Waiting or relying on antibiotics alone allows viral replication to continue, and FIP can progress quickly.

MolnuFIP has supported a large global community, with 100,000+ cats treated since 2019. That scale reflects how much the treatment landscape for FIP has changed in a short time.

Still, no treatment works the same way for every cat, and no responsible source can promise a specific outcome. The honest position is that antiviral therapy plus attentive supportive care, started early and supervised by a veterinarian, offers the strongest footing the current evidence supports. If you want a wider comparison of approaches, see this companion article on the best treatment for FIP in cats.

Are there cats that should not receive EIDD-1931?

Yes. EIDD-1931 has potential teratogenic effects, so MolnuFIP must not be used in pregnant, nursing, or breeding cats. If your cat is pregnant or feeding kittens, tell your veterinarian before any antiviral is considered so a safe plan can be made.

Any existing organ concerns, such as liver or kidney issues, should also be discussed before starting, so monitoring can be tailored to your cat. Your veterinarian is best placed to weigh these factors for your individual cat.

FAQ: Feline Infectious Peritonitis (FIP) Treatment in Australia

Is FIP treatable in Australia?

Yes, Feline Infectious Peritonitis (FIP) is treatable with direct-acting antiviral therapy given under veterinary supervision. Evidence shows many cats reach lasting remission, especially when treatment starts early and is paired with supportive care.

Does MolnuFIP contain GS-441524 or molnupiravir?

No. MolnuFIP for FIP contains EIDD-1931, the active antiviral metabolite of molnupiravir, at 15 mg per capsule. It does not contain GS-441524, and it is not the human molnupiravir capsule.

How long does FIP treatment take?

The general reference course runs up to 60 days, with a capsule every 12 hours per 2.5 kg of body weight, adjusted and supervised by your veterinarian. Finishing the full course matters, because stopping early is linked to relapse.

Can MolnuFIP treat neurological or ocular FIP?

No. MolnuFIP for FIP is indicated for wet, dry, and mixed or transitional forms, and it is not recommended for neurological or ocular FIP. If your cat shows seizures, head tilt, eye colour change, or vision problems, speak with your veterinarian about an appropriate plan.

How quickly will I see improvement?

Many Pawrents report a returning appetite, lower fever, and more energy within the first one to two weeks, though every cat responds differently. Keep a daily log and share it with your veterinarian at each recheck.

If your cat has just been diagnosed, you do not have to work through this alone. Take a moment to explore MolnuFIP's FIP treatment options and reach out to the team, and bring what you learn to your own veterinarian so you can build the safest, most informed plan for your cat together.