Can Cats Drink Soy Milk?

No, cats shouldn't drink soy milk—but there are a few things you should know before you panic if your cat had a lick. Soy milk seems like a logical solution if your cat is lactose intolerant. It's plant-based, no dairy, problem solved, right? Not exactly. While soy milk doesn't have the lactose that causes problems in regular milk, it has its own issues. Cats are obligate carnivores, which means their bodies are designed to get nutrients from meat, not plants. Soy milk doesn't provide anything your cat needs, and it can cause digestive upset in cats with sensitive stomachs.

Soy milk is not toxic in the way chocolate or grapes are toxic. A few laps won't poison your cat. But safe doesn't mean good. Soy milk contains plant compounds that cats can't digest well. Their digestive systems lack the enzymes needed to break down plant proteins efficiently. Some cats handle small amounts without problems. Others get diarrhea or gas. The bigger issue is what's added to soy milk. Many brands contain sugar, artificial sweeteners, thickeners, or flavorings. Some contain xylitol, which is extremely toxic to cats. Even unsweetened, plain soy milk offers zero nutritional value to cats.

The reasoning makes sense if you don't know cat biology. Your cat is lactose intolerant, so regular milk is out. You have soy milk in the fridge, it's dairy-free, why not share? Or maybe you're vegan and want to avoid animal products for your cat too. The problem is that cats didn't evolve to drink plant-based milk. They evolved to get moisture from prey—which is animal tissue, not plants. Soy milk might be a healthy choice for humans, but cats have completely different nutritional needs. What works for you doesn't work for them.

Not all plant-based milks are equally bad for cats, but none are good.

Cats are carnivores. Their bodies are optimized for digesting animal protein and fat, not plant material. When you give a cat soy milk, you're giving them something their digestive system isn't designed to handle. Soy contains phytoestrogens—plant compounds that mimic estrogen. In large amounts, these can potentially affect hormone levels, though the risk from a few laps of soy milk is minimal. More importantly, soy milk provides zero nutrition that cats need. It's not a protein source they can use efficiently. It doesn't contain taurine, an essential amino acid cats must get from their diet. It's basically empty calories that can fill up your cat without nourishing them.

Problems are more likely with regular feeding or sweetened varieties.

Technically yes, but that's a very low bar. Regular cow's milk causes digestive upset in most adult cats because of lactose. Soy milk doesn't have lactose, so it won't cause that specific problem. But that doesn't make it a good choice. Soy milk can still cause digestive upset for different reasons—plant compounds, additives, or simple incompatibility with feline digestion. If your cat is lactose intolerant and you want to give them something milk-like, lactose-free cat milk is a much better option. It's formulated specifically for cats and doesn't have the plant compounds that make soy milk questionable.

If you want to give your cat something special to drink, there are much safer options than soy milk. Lactose-free cat milk is formulated for feline digestion and comes in flavors cats enjoy. Plain water is always the best choice—fresh, clean, and available at all times. Low-sodium bone broth made specifically for cats can be a nice occasional treat. Wet cat food provides hydration along with proper nutrition. But honestly, most cats don't need anything beyond plain water. The idea that cats need milk comes from cartoons, not biology.

Absolutely not. Kittens need either their mother's milk or kitten formula. Their nutritional requirements during growth are very specific, and soy milk meets none of them.

If your cat had a small amount of plain, unsweetened soy milk, they're probably fine. But take action just in case.

No. Daily soy milk is not appropriate for cats. Even if your cat seems to tolerate it, you're giving them something with zero nutritional value. Cats need proper nutrition from cat food, not empty calories from plant-based milk. Regular soy milk consumption could lead to nutritional imbalances, especially if it's filling your cat up and reducing their appetite for proper food. There's also the question of phytoestrogens—plant compounds in soy that mimic hormones. While occasional exposure is unlikely to cause problems, daily consumption could potentially affect hormone levels over time.

Here's the thing: cats can't be vegan. Cats are obligate carnivores, which means they require nutrients that only come from animal tissue. Taurine, vitamin A in its active form, arachidonic acid—these are essential nutrients cats must get from meat. Plant-based diets, including soy products, don't provide what cats need to survive. If you're vegan for ethical reasons, that's your choice. But forcing a carnivore to eat a plant-based diet is harmful to the animal. Soy milk won't make your cat vegan; it will just give them digestive problems without providing any nutrition they need.

No. Soy milk is lactose-free, which is better than regular milk for lactose-intolerant cats. But lactose-free doesn't automatically mean cat-safe. Cats don't need milk at all—lactose-free or otherwise. If you want to give your cat a milk-like treat, use lactose-free cat milk that's specifically formulated for felines. These products are designed to be digestible and palatable for cats. Soy milk is designed for humans, not cats. The fact that it doesn't have lactose doesn't make it appropriate for feline consumption.