Hyperthyroidism is a serious condition that negatively impacts a cat’s health. It is also one of the most common endocrine disorders in older cats, occurring in about 10% of cats over the age of ten years. The most common clinical signs of this condition are weight loss, increased appetite, hyperactivity, and increased thirst, but can progress to vomiting and loss of appetite as the disease progresses. If your cat is showing any of these signs, you should speak to your vet immediately.
If your cat has already been diagnosed with hyperthyroidism, they are most likely already undergoing treatment, which usually includes an adjustment to your cat’s diet, medication, radioactive iodine therapy, or surgery. The most important part of a diet for a cat with hyperthyroidism is food that is low in iodine. Restricting iodine in a cat’s diet will help reduce the thyroid from overproducing the thyroid hormone, thyroxine, which causes hyperthyroidism.
It is also important that your cat’s food still contain some iodine, as a diet deficient in this mineral can trigger a negative feedback reaction which can also make your cat’s condition worse. Fortunately, all AAFCO approved foods must contain a minimum amount of iodine, so we just need to look for foods that have the ideal amount, plus some other essential nutrients.
To combat the weight and muscle loss that accompanies hyperthyroidism, The Feline Hyperthyroid Treatment Center recommends a diet that contains approximately:
- 40% protein
- 50% fat
- <10% carbohydrates (fiber)
- 2 ppm iodine
The levels listed above are based on dry matter, unlike those on the label of wet food, which usually has around 75-80% moisture, so the nutrient figures will always appear lower than in dry food. To get a rough approximation of these values for wet food, multiply them by 4 or 5. For example, wet food with 10.5% protein and 75% moisture has the rough equivalent of 42% protein. A food with 8% protein and 80% moisture will have approximately 40% protein.
We also recommend avoiding*:
- SOY-containing foods
- BPA in canned food linings
- Too much fish
- Plastic food and water bowls (replace with glass, ceramic or metal)
- Storing food in plastic containers
- Ultra-high or ultra low iodine diets
*Following these recommendations for all cats, not just those with hyperthyroidism, may reduce your cat’s risk of developing the condition.
Your veterinarian’s advice is essential, especially if your cat has a medical condition. Never change the diet of your cat suffering from hyperthyroidism, without checking with your vet.
The foods reviewed here were chosen because they have certain characteristics that might help with some of the causes or consequences of this medical condition. However, they are not a medical treatment or a substitute for medical treatment. Keep in mind that each medical case is different and what works for some pets may not work for others. Your veterinarian is the right person to advise you on the best diet for your pet’s case.
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A Quick Comparison of Our Favorites in 2025
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Best Overall
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Hill’s Prescription Diet y/d Thyroid Care Cat Food |
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Best Value
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Hill’s Prescription Diet y/d Thyroid Care Cat Food |
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Premium Choice
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Wellness Complete Health Canned Cat Food |
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Instinct Original Grain-Free Pate Canned Cat Food |
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Instinct Limited Ingredient Diet Rabbit Dry Cat Food |
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The 6 Best Cat Foods for Hyperthyroidism
1. Hill’s Prescription Diet y/d Thyroid Care Cat Food – Best Overall
| Protein: | 9.9% |
| Fat: | 7.5% |
| Fiber: | 9.1% |
| Iodine: | 0.04 ppm |
| Flavor: | Chicken |
| Texture: | Pâté |
| Size: | 5.5 oz. x 24 |
| Note – wet food | |
The best overall canned food for hyperthyroid cats is Hill’s Prescription Diet y/d Thyroid Care Cat Food. This is the only canned food made specifically to help cats with hyperthyroidism, and it is available in a case of 24 cans that are 5.5 ounces each. It has been clinically proven that this Thyroid Care food will restore thyroid health in as little as 3 weeks. Since thyroid issues usually happen to older cats, kidney damage is another concern, and this food is also low in phosphorus and sodium, which will help with kidney health. It contains omega-3 and -6 for healthy skin and coat and added taurine and carnitine for a healthy heart and weight.
On the downside, it is expensive, and it contains pork by-products and corn flour. You’ll also need a vet authorization to purchase this cat food.
- Only canned food for cats with hyperthyroidism
- Clinically proven to benefit thyroid health in 3 weeks
- Low in sodium and phosphorus for kidney health
- Omega-3 and -6 for healthy coat and skin
- Taurine and carnitine for heart health and weight
- Expensive
- Contains corn flour and pork by-products
- Only one flavor – no good for cats with chicken allergy/intolerance
- Must eat no other food to be effective
2. Hill’s Prescription Diet y/d Thyroid Care Cat Food — Best Value
| Protein: | 30% |
| Fat: | 20% |
| Fiber: | 3.5% |
| Iodine: | 0.2 ppm |
| Flavor: | Chicken |
| Texture: | Dry kibble |
| Size: | 4 and 8.5 lbs |
Our pick for best value dietary treatment for cats with hyperthyroidism is Hill’s Prescription Diet y/d Thyroid Care Cat Food. Like our top choice, this food is specifically designed to help cats with hyperthyroidism and is proven to improve thyroid health in three weeks. It decreases the T4 hormone production and helps support urinary, heart, and kidney health. It also aids in a healthy immune system and a healthy coat and skin.
However, it is still quite expensive, and the ingredients aren’t what we would ordinarily see as ideal. Corn gluten meal is listed as the first and, therefore, the main ingredient, which is unusual for a cat food, but it is very effective in treating the condition without medication, provided the cat eats nothing else.
- Specifically meant to help cats with hyperthyroidism
- Regulates thyroid activity
- Supports heart, kidney, and urinary health
- Aids in a healthy immune system and skin and coat
- Expensive
- Corn gluten meal is the main ingredient
- Only one flavor – no good for cats with chicken allergy/intolerance
- Must eat no other food to be effective
3. Wellness Complete Health Canned Cat Food
| Protein: | 10.5% |
| Fat: | 8% |
| Fiber: | 1% |
| Iodine: | 0.83 ppm |
| Flavor: | Variety of flavors available |
| Texture: | Smooth loaf |
| Size: |
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| Note – wet food | |
Another great choice for food for cats with hyperthyroidism is Wellness Complete Health Cat Food. Now, this food isn’t super cheap, but when you have a cat with such a serious health condition, you do need to pay more to keep them in optimal health. This pâté is available in three different-sized cans and is grain-free, with real meat as the main ingredient. It’s full of omegas and antioxidants for immune system support and healthy skin and coat.
On the downside, the food has a thicker and drier texture that some cats might also find off-putting.
- Three different-sized cans
- Variety of grain-free flavors
- Antioxidants and omegas for the immune system and healthy skin and coat
- Some cats won’t eat it
- The texture might be dry and thick
4. Instinct Original Grain-Free Pate Canned Cat Food
| Protein: | 10% |
| Fat: | 7% |
| Fiber: | 3% |
| Iodine: | 1.0 ppm |
| Flavor: | Variety of flavors available |
| Texture: | Pâté |
| Size: |
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| Note – wet food | |
Instinct’s Original Grain-Free Cat Food is a pâté that comes in two sizes and is grain-free. The first three ingredients are whole meats, including chicken, turkey, and chicken liver, which can help build your cat’s muscles. It doesn’t contain any animal by-products, grain, wheat, corn, or artificial preservatives or colors. It has omega fatty acids to improve your cat’s skin and coat, and the cans are BPA-free.
The disadvantage is that the texture of this food is also quite loose and almost runny, which may or not be a bad thing. This food is also on the upper end of the recommended iodine levels, but it would still be suitable for a cat whose hyperthyroidism is well controlled.
- Comes in two sizes, cans are BPA free, and pâté is grain-free
- First three ingredients are whole meats
- Doesn’t contain by-products, corn, wheat, grain, artificial preservatives, or colors
- Omega fatty acids for healthy coat and skin
- Higher iodine levels, not suitable for newly diagnosed cases
- Pâté is on the runny side
5. Instinct Limited Ingredient Diet Rabbit Dry Cat Food
| Protein: | 35% |
| Fat: | 19% |
| Fiber: | 5.5% |
| Iodine: | 0.9 ppm |
| Flavor: | Rabbit |
| Texture: | Dry kibble |
| Size: | 5 and 10 lbs |
Instinct’s Limited Ingredient Cat Food comes in two sizes and has limited ingredients, which also works for cats with food sensitivities. It is only made with one animal protein (rabbit) that is freeze-dried, and it doesn’t contain any grains, dairy, eggs, fish, wheat, or artificial preservatives or colors. It does have natural antioxidants and omegas to boost the immune system and the skin and coat.
However, some cats might experience stomach upset after eating this food, and it does tend to be rather smelly. Also, the food is quite dark in color — almost black — but this is normal because it has a raw coating.
- Limited ingredients for cats with food sensitivities
- Doesn’t contain grains, dairy, eggs, artificial colors, or preservatives
- Natural antioxidants and omegas for the immune system, coat, and skin health
- Some cats might experience stomach upset
- The food is rather smelly
6. Stella & Chewy’s Freeze-Dried Raw Cat Food
| Protein: | 45% |
| Fat: | 25% |
| Fiber: | 5% |
| Iodine: | 2.56 ppm |
| Flavor: | Variety of flavors available |
| Texture: | Freeze-dried pieces |
| Size: |
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Stella & Chewy’s Freeze-Dried Raw Cat Food is high in protein because it’s raw food but conveniently freeze-dried to help preserve the nutrition. You can feed it as is to your cat or rehydrate it with water. This food is made in the U.S. and contains only organic fruits and vegetables. It doesn’t contain any fillers, gluten, grains, or artificial flavors or colors.
On the negative side, it is expensive, and some cats might not want to eat it. You might also find that the morsels are big for a small cat, but this can be great for keeping teeth clean.
The iodine levels listed are on a dry matter basis, so are higher than others on this list, but the as fed value would be expected to be somewhat lower. However, we would only recommend feeding this diet to cats that have well-controlled hyperthyroidism.
- High in protein
- Raw food that is freeze-dried to preserve nutrition
- Doesn’t contain fillers, gluten, grains, or artificial flavors, or colors
- Only includes organic fruits and vegetables
- Expensive
- The morsels are big
- Higher iodine content
Buyer’s Guide: Selecting the Best Cat Foods for Hyperthyroidism
We have a few more things for you to consider before you make your first purchase of a new cat food. It’s best to be well-informed, particularly because this kind of food is expensive, so you’ll want to consider every aspect beforehand.
Cat Food Ingredients
This is the most essential part of choosing food for your cat. If you want to give your cat food that does not contain too much iodine, it is important to know what ingredients naturally have iodine:
| Seafood: | Fish, shrimp, seaweed |
| Dairy products: | Yogurt, cheese, milk |
| Egg: | Mainly yolks |
| Salt: | Iodized table salt |
So, before you purchase your cat food, always read the ingredients list first. Check that the ingredients containing iodine are minimal or not included and that the first three to five ingredients should be whole meat whenever possible.
Most foods don’t list the amount of iodine contained, so you’ll want to contact the manufacturer or look through reviews to find out this information. Ideally, the food should contain between 0.05 and 0.2 ppm of iodine, however, only products number one and two in this list stay under that limit, thus they are considered dietary treatments. Iodine levels should ideally be less than 1.0 ppm on an ‘as fed’ basis.
Iodine: ppm or %?
You might notice that iodine levels are sometimes written as ppm (parts per million) and other times listed as a percentage, using the two interchangeably. However, this is actually incorrect. AAFCO feeding guides recommend non-hyperthyroid cats consume foods containing around 0.6mg/kg, which is the equivalent of 0.6 ppm or 0.00006%, while for hyperthyroid cats, the iodine content we aim for is 0.2 ppm, which is equivalent to 0.2 mg/kg, or 0.00002%.
Be aware that some sites may list this value as a % (eg. 0.2%), but the likelihood is that this figure should be in ppm. If in doubt, get in touch with the manufacturer to find out the iodine levels in mg/kg.
The Best Cat Diet
Cats with hyperthyroidism should have a diet with 5–10 % carbohydrates, 40% protein, and 30–40% fat. Generally speaking, a diet that is high in protein, low in carbohydrates, and has a moderate amount of fat is what you need to be looking for.
Since cats with hyperthyroidism tend to lose weight, they need the extra protein and fat to help them put on weight and to contribute to a healthy coat. A cat with hyperthyroidism tends to have a rather ratty-looking coat.
It’s a balancing act because older cats might have other issues beyond hyperthyroidism, such as diabetes or kidney disease. For this reason, wet or moist food is considered to be better than dry for the extra water content.
Both radioactive therapy and surgery cure hyperthyroidism and feeding a high-protein diet can help a cat recover the muscle and weight lost during the disease process. However, it is fairly common for cats to be diagnosed with renal disease after radioactive therapy. This happens because hyperthyroidism was masking the diagnostic markers of renal disease on the cat’s blood samples, once the hypothyroidism is resolved, the renal disease becomes evident in the blood parameters.
High protein diets are contraindicated for renal disease and the cat will need a different dietary approach. This is why it is very important to follow up with your veterinarian to find out what is the best diet specifically for your cat’s case and condition. Each cat is unique and feeding the right diet will make a huge difference in their health.
Dietary Treatments and Multiple Pets
Always speak to your vet about your cat’s diet and possible choices in food before you purchase anything. If you will try a dietary treatment, it’s important to note that if you’ve put your cat on a special prescription diet to treat their hyperthyroidism (ie. Hills y/d), you shouldn’t feed them anything else — no treats and no other food.
Some of these special foods, particularly the prescription ones, are only meant for cats with hyperthyroidism. If you have other pets in the house that like to eat your cat’s food, you’ll need to find a way to feed your cat and prevent the rest of the animals from eating it, and vice-versa.
In the majority of cases however, a hyperthyroid-friendly food should be appropriate for other cats in your house, depending on whether they have any health conditions, but check with your vet to be sure.
High-quality cat food is an important part of fostering a long and healthy life for your cat but the right cat food and water dish will promote good posture, offer whisker relief, and aid in good digestion. The Hepper NomNom Cat Bowl is our favorite bowl since it offers all of the above and is beautifully crafted to meet modern home stylings. The wide tray design catches any food and water spills and the entire setup is dishwasher safe. Learn more about the Hepper NomNom Cat Bowl here. At PangoVet, we’ve admired Hepper for many years and decided to take a controlling ownership interest so that we could benefit from the outstanding designs of this cool cat company!
How We Determined This List of Cat Foods for Hyperthyroidism
All the cat foods reviewed in this article were chosen by our writers, editors, and team of experienced veterinary professionals to ensure that they are safe and meet the care needs of your pet. When choosing which cat foods to feature, we took into account brand reputation, personal and hands-on experience, reviews from other customers, and of course, feedback from our beloved pets, to make sure to bring you only the best of the best. We at PangoVet want to give you only the best products to choose from in our reviews, to ensure that they meet your pets’ needs for optimal health and well-being.
Why Trust PangoVet?
We are a team of experienced veterinarians, writers, and editors who are pet owners ourselves, so we understand how important your pets and the products they use and consume are to you. Whether you are caring for a furry, scaly, or feathered friend, we make sure that you have honest and unbiased reviews of the top cat foods on the market, so you can make an informed decision.
Final Thoughts
If you’re on the lookout for the best overall cat food to help with your cat’s hyperthyroid, Hill’s Prescription Diet y/d Thyroid Care Cat Food is the best bet for dietary treatment because it’s specially designed for this condition. You’ll need to speak to your veterinarian about the best value dietary treatment option Hill’s Prescription Diet y/d Thyroid Care Cat Food. It’s expensive but very effective!
Wellness Complete Health Cat Food is a better protein choice for a cat that is recovering from radioactive therapy treatment and has not been diagnosed with kidney disease.
We hope that our reviews will help you to be informed and know about the different options of food for your cat. Hopefully, the right diet, medication, or treatment will see your cat get back to optimal health as soon as possible.
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Featured Image Credit: Nils Jacobi, Shutterstock
