A food-allergy year costs 1,100 to 2,400 dollars in the US, 700 to 1,500 pounds in the UK, and 5,700 to 12,000 yuan in China, and 60 to 65 percent of that is the diet itself. The 8-week elimination trial is the cheap part at 150 to 400 dollars; the expensive part is the 12 months that follow, when the cat must stay on one protein source and every recheck restarts the clock.
What the 8-week trial costs to run
An 8-week trial needs 2 to 3 bags of a hydrolyzed or novel-protein diet. In the US a 1.8 kg bag runs 45 to 75 dollars and lasts 25 to 35 days for a 4.5 kg cat eating 60 to 70 g a day, so the trial alone is 150 to 400 dollars including the first recheck. The UK sits at 30 to 55 pounds per 2 kg bag, China at 300 to 600 yuan per 1.5 kg bag. Nothing else enters the bowl for 56 days: no treats, no table food, no flavored toothpaste, and no other cat's food, which for a 2-cat house means a second bowl and often a second bag.
Why prescription diets cost 5 to 10 times regular food
Hydrolyzed diets are priced at 25 to 42 dollars per kg, which is what a 45 to 75 dollar 1.8 kg bag works out to, against 4 to 8 dollars per kg for supermarket dry food. The premium pays for a single production line, protein hydrolysis to fragments under 10 kDa, batch testing, and a narrow distribution channel. A 4.5 kg cat on 65 g a day eats 24 kg a year, which is 600 to 1,000 dollars at prescription prices, up to 1,500 where part of the diet is canned, and 96 to 192 dollars at supermarket prices. That gap, not the vet visit, is the annual bill.
Three rechecks, and why the timing matters
The standard schedule is a recheck at week 4, week 8 and week 12, at 60 to 120 dollars each in the US, 40 to 80 pounds in the UK, 150 to 350 yuan in China. Week 4 answers one question: is the itching score falling on a 0 to 10 scale. Week 8 decides whether the trial continues or the diagnosis moves from food to environmental allergy. Week 12 is the challenge or the maintenance plan. Moving a recheck from week 8 to week 10 rarely changes the outcome, but skipping week 8 does, because a cat still scratching at day 56 needs a different plan, not a longer bag.
Twelve months by region: US, UK, China
| Line item | US (USD) | UK (GBP) | China (CNY) |
|---|---|---|---|
| 8-week trial diet, 2-3 bags | 150-400 | 90-240 | 700-1,800 |
| Recheck visits, 3 at 60-120 | 180-360 | 120-240 | 450-1,050 |
| 12-month maintenance diet | 700-1,500 | 450-950 | 4,500-9,000 |
| Dermatology consult (optional) | 150-350 | 120-280 | 300-800 |
| Skin cytology or ear swab | 45-120 | 35-90 | 80-250 |
| Year 1 total | 1,100-2,400 | 700-1,500 | 5,700-12,000 |
These are 2026 general-practice figures for a mid-size city, and each row swings 1.5 to 3 times with city size and hospital tier. A university dermatology service at the top of every range can double the consult line alone; a municipal clinic at the bottom can halve the recheck line. The diet line moves least, because it is set by the manufacturer rather than the clinic, though online and clinic pricing for the same bag can differ by 20 to 30 percent.
What inflates the total
Four add-ons account for most overruns. A dermatologist consult at 150 to 350 dollars adds 45 to 90 minutes and often an intradermal skin test at 250 to 500 dollars. Secondary bacterial or yeast infection needs cytology at 45 to 120 dollars plus 2 to 4 weeks of topical treatment at 30 to 90 dollars. Otitis media workup adds 200 to 600 dollars if the ear canal is narrowed. And a second cat on the same diet doubles the food line, which is the single largest multiplier in a multi-cat house.
Where year 2 gets cheaper
Year 2 typically runs 800 to 1,700 dollars in the US, 500 to 1,100 pounds in the UK, 4,800 to 9,700 yuan in China: 2 rechecks instead of 3, no trial bags, and often a switch from hydrolyzed to a limited-ingredient diet at 8 to 14 dollars per kg. The saving is real but conditional. A cat that relapses within 6 months goes back to the trial diet and the year 2 total returns to the year 1 level. The long-run math for a cat that stays on a prescription diet for 3 to 5 years is set out in prescription diet annual cost. This is also the pattern that matters most in an older cat, where a diet change interacts with CKD staging and the numbers in senior cat final year cost start to overlap.
When waiting costs more than the diet
Stop the trial and book a visit if the itch score has not dropped by 50 percent at week 8, if weight falls more than 10 percent, if vomiting or diarrhea appears more than 3 times a week, or if the cat stops eating for 24 hours. Those four signs point away from food allergy and toward IBD, lymphoma, or a metabolic problem, and each week of delay adds 200 to 800 dollars to the workup that follows. A cat that develops a head tilt or drooling needs the ear checked within 48 hours, not at the week 12 recheck.
Reading the bag before paying for it
Two numbers on the label decide whether the money is well spent. The guaranteed analysis should list a single animal protein source in the first 3 ingredients, and the kcal per kg should be within 10 percent of the current diet so the cat does not lose weight on a smaller volume. A bag with 3,500 kcal per kg versus 4,100 means roughly 17 percent more grams per day, and a 1.8 kg bag that lasted 30 days now lasts 25. Compare cost per 1,000 kcal rather than cost per bag, and log the first 14 days in the cost calculator so the monthly figure is visible before month 3.
Five steps for the first 8 weeks
- Buy 3 bags before day 1, not 1; a mid-trial reorder at a 20 percent premium is the most common overrun.
- Weigh the cat on day 0, day 28 and day 56 on the same scale.
- Photograph the itch score weekly on a 0 to 10 scale for the vet to compare.
- Feed every cat in the house the same diet for 56 days, or feed separately behind a door.
- Book all 3 rechecks at the first visit; the week 8 slot fills 2 to 3 weeks out.
Terms mentioned in this article
Frequently asked
Can I use a supermarket limited-ingredient food instead of a prescription diet?
Sometimes, but the risk is cross-contamination on shared lines. A trial diet needs a protein the cat has never eaten plus a factory that does not also run chicken or fish on the same equipment. Supermarket foods at 4 to 8 dollars per kg rarely guarantee that, and a failed 8-week trial at 150 to 400 dollars costs more than the difference in food price.
How much does the diet cost per month for one cat?
At 60 to 70 g a day, a 4.5 kg cat eats about 2 kg of dry diet a month. That is 50 to 85 dollars in the US, 33 to 55 pounds in the UK, and 400 to 750 yuan in China at prescription prices. A hydrolyzed diet runs at the top of that band, a limited-ingredient maintenance diet at the bottom.
Is the 8-week trial long enough to judge?
Eight weeks covers 2 skin cycles in most cats, and about 70 percent of food-allergic cats show a 50 percent drop in itch score within that window. A cat with no improvement at week 8 usually needs the diagnosis re-examined rather than a longer trial, which is why the week 8 recheck is the one appointment worth keeping.