Hill’s does not sell a single food called “hypoallergenic.” It sells three Prescription Diet lines for dogs with food allergies: z/d (hydrolyzed protein), d/d (one uncommon protein), and Derm Complete (egg and rice). All three need your vet’s authorization, and all three work best as part of a strict elimination diet trial.
“Hypoallergenic” is a marketing word, not a regulated pet food term. Veterinary nutritionists at Tufts University point out that no diet is completely hypoallergenic. What matters is whether a food avoids the proteins your dog reacts to.
Hill’s Allergy Diets at a Glance
| z/d | d/d | Derm Complete | |
|---|---|---|---|
| Approach | Hydrolyzed protein | Limited ingredients, single intact animal protein | Single intact animal protein, plus skin support |
| Protein | Hydrolyzed chicken liver and hydrolyzed chicken | Duck, salmon, or venison | Egg |
| Main carbohydrate | Corn starch | Potato | Rice |
| Calories per cup (dry) | 348 | 364 to 365 | 389 |
| Forms | Dry, Small Bites, canned, plus a low-fat hydrolyzed soy version | Dry and canned | Dry, canned, and a puppy dry food |
| Vet authorization | Required | Required | Required |
Hill’s z/d: Hydrolyzed Protein
In a hydrolyzed diet, the protein is broken into pieces too small for the immune system to recognize. Hill’s says z/d is formulated without intact animal protein and is clinically proven to help avoid adverse food reactions.
- First ingredients (dry): corn starch, hydrolyzed chicken liver, hydrolyzed chicken, ground pecan shells, powdered cellulose, flaxseed.
- Nutrients (dry matter): about 20% protein, 14.5% fat, 6.4% fiber.
- Limits: Hill’s does not recommend it for puppies or for pregnant or nursing dogs.
Corn starch as the first ingredient surprises some owners, but it is the point of the recipe. Purified starch supplies energy with very little protein, and protein is what triggers a food allergy. We cover this food in detail in our Hill’s z/d dog food review.
Hill’s d/d: One Uncommon Protein
d/d takes the “novel protein” route. Each recipe pairs potato with a single animal protein that many dogs have not eaten before.
- Dry recipes: Potato and Duck, Potato and Salmon, Potato and Venison.
- Canned recipes: duck, salmon, and venison.
- First ingredients (Potato and Duck dry): potatoes, potato starch, duck, potato protein, soybean oil, coconut oil.
- Nutrients (dry matter): about 18.5% protein and 16% fat.
A novel protein only helps if it is truly new to your dog. If your dog has already eaten duck treats or salmon kibble, that recipe is not novel anymore. Tell your vet about every food and treat your dog has had.
Hill’s Derm Complete: Egg and Rice
Derm Complete uses egg as its single intact animal protein and is aimed at dogs with food sensitivities, environmental sensitivities, or both. Hill’s claims visible skin improvement in 21 days in dogs with food sensitivities.
- First ingredients (dry): brown rice, brewers rice, egg product, rice protein concentrate, soybean oil, flaxseed.
- Nutrients (dry matter): about 17% protein and 17% fat.
- Puppies: there is a separate Derm Complete puppy food.
Egg is not a common trigger. In a 2016 review of 297 dogs with food allergies, egg accounted for about 4% of cases. A dog that is allergic to egg should still avoid this food.
What About Science Diet Sensitive Stomach and Skin?
This over-the-counter Hill’s food is often confused with the allergy diets. It contains chicken, chicken meal, and egg, so it is not an elimination diet and will not help a dog that is allergic to chicken. It is meant for general digestive and coat support. Read more in our Science Diet Sensitive Stomach and Skin review.
Hill’s Hypo Treats
Hill’s also makes Prescription Diet Hypo Dog Treats from corn starch and hydrolyzed chicken liver, at 17 calories each. Hill’s lists them as compatible with z/d, d/d, and Derm Complete. Ask your vet before using any treat during a diet trial.
Which Foods Do Dogs React To?
The same 2016 review in BMC Veterinary Research found these were the most common triggers in dogs with confirmed food allergies:
- Beef: 34%
- Dairy: 17%
- Chicken: 15%
- Wheat: 13%
- Soy: 6%
- Lamb: 5%
Grains are far from the top of the list, so switching to a grain-free food rarely solves an allergy. If you simply want to avoid certain grains, see our guide to dog food without corn, wheat, or soy.
How an Elimination Diet Trial Works
There is no reliable shortcut test for food allergy. VCA Animal Hospitals and Tufts both say blood, saliva, and hair tests are not accurate. The diagnosis comes from a diet trial:
- Feed only the trial food. VCA recommends at least eight weeks. Skin problems can take 8 to 12 weeks to settle. Stomach signs often improve sooner.
- Remove everything else. That means no other treats, table scraps, rawhides, dental chews, flavored toothpaste, or supplements. Ask your vet whether any flavored chewable medicines need to be swapped.
- Re-challenge. If the signs clear up, your vet may have you feed the old food again. If the signs return, usually within about a week, the allergy is confirmed.
Why not an over-the-counter limited ingredient food?
A 2018 review of studies that tested pet foods found undeclared ingredients in many of them, including 33% to 83% of the “novel” or “limited ingredient” diets tested. Even a trace of the wrong protein can spoil a trial. VCA notes that over-the-counter limited ingredient foods are often not made in dedicated facilities, which is one reason vets prefer prescription diets for a trial.
Cost and How to Buy
Hill’s says you need a vet’s recommendation wherever you buy these foods. Online retailers such as Chewy ask for your clinic’s details at checkout and confirm the authorization with your vet.
| Food (dry) | Small bag | Large bag |
|---|---|---|
| z/d | 8 lb: about $59 | 25 lb: about $136 |
| d/d Potato and Salmon | 8 lb: about $62 | 25 lb: about $142 |
| Derm Complete | 6.5 lb: about $52 | 24 lb: about $143 |
These are Chewy list prices from October 2026.
Recall History
In 2019 Hill’s recalled a number of canned dog foods because of elevated vitamin D from a supplier’s vitamin premix. The list included canned z/d in the 5.5-ounce and 13-ounce sizes. No dry foods or treats were affected, and the FDA’s list did not include d/d or Derm Complete.
Pros and Cons
Pros
- Three different approaches, so there is a fallback if one does not suit your dog
- Hydrolyzed and single-protein recipes made for elimination trials
- Dry, canned, small-kibble, and puppy options, plus matching treats
- Widely stocked by vets and online pharmacies
Cons
- Expensive, at roughly $5.50 to $8 per pound
- Vet authorization needed
- Starch-heavy ingredient lists that look unappealing next to regular dog foods
- z/d is not for puppies or for pregnant or nursing dogs
This article is general information, not veterinary advice. Itching, ear infections, and stomach upset have many causes besides food. See your vet for a diagnosis before starting an allergy diet.
Bottom Line
Hill’s z/d, d/d, and Derm Complete are well-established tools for finding and managing food allergies in dogs. A hydrolyzed diet such as z/d is often the first choice, and Tufts nutritionists call hydrolyzed diets the best option in many cases. d/d and Derm Complete are useful when a dog does better on a single intact protein. None of them will work unless the trial is strict, so plan it with your vet and feed nothing else for at least eight weeks.
