How Much Does FIP Treatment Cost for a Cat? GS-441524 Prices Before and After the FDA's 2024 Compounding Decision
Feline infectious peritonitis (FIP) used to be a diagnosis owners were told to grieve. Now it comes with a price tag that has fallen sharply. Here is what owners reported paying and what changed in 2024.
What owners reported paying before 2024
The best public data is an owner survey in Frontiers in Veterinary Science (Negash et al., June 26, 2024). Of 151 respondents, 143 answered the cost questions and 141 finished the 12-week course. The average drug spend was $3,103, from $0 to $10,000. A 2020 survey had put it at $4,920, so the drug bill fell about 40%.
Why that number has limits
The figures are self-reported, and the drug was unlicensed. Many owners bought it through online communities. A $0 answer usually means a gift, not free treatment. Treat it as a 2022 snapshot, not a quote.
The vet bill sits on top of the drug bill
The same survey asked about veterinary costs for monitoring, exams and supportive medications such as gabapentin and B12. That averaged $2,437, from $0 to $20,000. The clinic side was nearly as large as the drug side.
What changed in May 2024
On May 10, 2024, the FDA said that, with no approved FIP drug available, it would not enforce new animal drug requirements against GS-441524 compounded for a specific cat on a veterinarian's prescription (GFI #256). A licensed compounding pharmacy can fill that prescription, but cannot keep it as office stock. The FDA still calls compounded drugs unapproved, so this is tolerance, not approval.
What compounding did to the price
A March 2026 study in Pathogens (Van der Walt et al.) says regulated compounded formulations became available at much lower cost, "less than 1000 USD for most cats in 2025." That is a description, not a price list. A cat's weight still matters, since larger cats need more drug, so ask your clinic for a written estimate.
Line items to ask about
A course is commonly described as 84 days, with recheck blood work every few weeks. The price of those visits is not published reliably, so the clinic's estimate is the number that counts. Ask about exam fees, bloodwork, shipping and refills.
Comparing and paying for it
FIP is a one-time course, not a lifelong prescription. Our hyperthyroidism cost guide and osteoarthritis cost guide show recurring bills for contrast. Whether insurance pays depends on the policy and when the illness began, so read waiting periods and pre-existing conditions first, and ask the clinic for itemized costs.
Sources: Negash et al., Frontiers in Veterinary Science (2024), doi 10.3389/fvets.2024.1377207; Van der Walt et al., Pathogens 15(3):337 (2026); FDA announcement on compounded GS-441524 (May 2024).. This is cost information, not veterinary advice; talk to your veterinarian about diagnosis and treatment.
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