May 27, 2025, 9:26 am | Read time: 8 minutes

Adorable kittens leisurely licking milk—a picture deeply ingrained in the collective memory. However, what has long been considered a loving gesture by pet owners can actually be harmful. Learn why this popular household drink poses a health risk for cats.

Milk and Cats—A Cultural Connection with Consequences

Cats have lived alongside humans for over 9,000 years, as finds from Cyprus confirm. Initially attracted by rodents, they soon became valued mousers—and were often “rewarded” with milk on farms. This early association laid the foundation for the persistent image of the milk-drinking cat.

In 1877, for example, Scottish doctor Gordon Stables recommended in his cat book that cats should always have two bowls—”one for water and the other for milk”—and praised oatmeal with milk as the ideal breakfast for cats. Since then, the image of the milk-drinking cat has been further solidified by art, literature, and media. However, modern science now clearly contradicts this, stating that cats should not be given milk at all.

Lactose Intolerance—The Norm for Adult Cats

While kittens, like all mammals, initially drink milk, their bodies produce an enzyme in the intestine called lactase to metabolize and tolerate the lactose it contains. This enzyme breaks down lactose, making milk easily digestible for young cats. After weaning from their mother’s milk (around six to twelve weeks), the production of the enzyme necessary for smooth lactose digestion decreases. After that, most cats are indeed lactose intolerant.

This is also true for most adult mammals—lactose intolerance is actually the normal state. The exception is humans, who are accustomed to consuming milk from other animals, such as cows, sheep, or goats. The level of lactose intolerance is significantly higher in Asian countries, where soy is more common and animal milk is less so. In Germany, however, lactose intolerance can become a problem because many foods contain dairy products, as nutritionist Beke Enderstein reports to colleagues at FITBOOK.

The extent of this natural intolerance in cats depends on the individual residual enzyme production—similar to humans. But even for young kittens, cow’s milk is unsuitable. Their mother’s milk contains significantly less lactose, so kittens should ideally drink from their mother or be fed special kitten milk. ¹

Moreover, although rare, some cats can also develop an allergy to dairy products.

The Unpleasant Consequences When Cats Drink Milk

If lactose cannot be digested, it reaches the large intestine, where it is fermented by bacteria. This produces gases and acids that can cause discomfort such as bloating, abdominal pain, constipation, or even nausea and vomiting. Diarrhea is the most common symptom in cats.

If milk is fed regularly, this can become chronic—with potentially serious consequences such as dehydration, electrolyte imbalances, and malnutrition. In extreme cases, this can be life-threatening. Liver damage can also result if the lactose processed here burdens and even damages the organ over time. Obesity can also be a consequence if cats frequently consume milk, as it contains many calories and can lead to weight gain if not accounted for in their regular diet.

Why Cats Still Like Milk

Cats prefer protein- and fat-rich foods—just like cow’s milk. It also contains casein, a protein that breaks down into alpha-casozepine in the body—a substance that studies suggest can have a calming effect on cats. This explains why some animals develop a positive association with milk over time, even if it doesn’t agree with them.

What Types of Milk Can Cats Drink?

Especially when you get cats at an age when they should still be nursing, you need to provide them with suitable alternatives. Other types of milk specifically designed for cats are also available in pet stores. And what about soy, oat, or coconut drinks? The following section reveals more.

Kitten Milk

Kitten milk is suitable as a substitute for mother’s milk in the first weeks of life for newborn cats. Supplementing with kitten milk may be necessary if the mother cat does not produce enough milk or if the kittens are orphaned. Like mother’s milk, it contains the three amino acids taurine, arginine, and methionine. It provides the young with enough energy in the form of fat and milk sugar (lactose), whereas regular cow’s milk could lead to deficiencies. The gradual transition to regular food begins between the third and fourth week. Kittens that are normally nursed and adult cats do not need kitten milk.

Lactose-Free Cat Milk

If you want to treat an adult cat (from the third month of life), you can buy special cat milk. Due to its special preparation, it is lactose-free or significantly lactose-reduced and enriched with taurine, extra vitamins, and calcium.

Like cow’s milk, this special cat milk is also a calorie bomb and should only be given as a treat and in small amounts. Diluted with a little water, it sometimes stimulates the thirst of poor drinkers. But beware: if the cat is not used to this type of treat, the well-intentioned cat milk may be rejected.

Almond, Oat, Soy, and Coconut Milk

If you occasionally add milk alternatives to your morning coffee, you might consider offering your cat plant-based alternatives like almond, soy, oat, or coconut milk. One advantage of these milk alternatives is that they are lactose-free and, especially in the case of soy, have a relatively high protein content. However, oat milk is often very sweet, a taste that cats cannot perceive and therefore do not like.

Whether a cat tolerates these alternatives well and does not have an allergic reaction should be closely observed during the first feeding. Depending on the milk alternative, they have varying calorie contents. Especially with coconut milk, depending on the form, the entire daily calorie requirement can be quickly met.

• 100 ml coconut drink: approx. 18 calories
• 100 ml almond milk: approx. 26 calories
• 100 ml oat milk: approx. 50 calories
• 100 ml soy milk: approx. 54 calories
• 100 ml canned coconut milk (full-fat): 197 calories

Alternatives for Higher Fluid Intake

Many people give their cats milk to encourage them to drink. However, since even cat-friendly types usually contain quite a few calories, alternatives should be considered. One option is broth, which is best made by boiling meat that the cat likes to eat. It’s important not to use salt or spices.

Nowadays, low-calorie soups or broths for cats are also available in pet stores. These have an average of 13 calories per 100 ml. You just have to try out which type your cat likes. These soups are also available for cats that already have kidney problems, with adjusted nutritional values.

We have compiled more tips on how to get cats to drink more water in this article.

Can Cats Eat Cheese?

Cheese is a good protein source for cats, but it is also high in calories. However, the milk sugar disappears in many cheeses that are aged a bit longer. This is not the case with fresh cheese, processed cheese, or other cream cheeses.

Parmesan and similar types can be given as treats without expecting any issues. A small spoonful of cottage cheese has also been known to help with diarrhea—but it could also worsen it. If you’re unsure, it’s best to avoid all processed dairy products for cats. Cats with kidney disease should also avoid cheese due to its high salt and phosphate content.

More on the topic

Cheese type check Are cats allowed to eat cheese? A veterinarian clarifies

Healthy ingredients 4 recipes for homemade dog ice cream

A health consultant explains No more cat food in the house? Here is an alternative you could feed your cat

Expert Recommends Avoiding Milk Altogether

Conclusion: “Milk is not a natural part of a cat’s diet,” explains Julia Henning, a doctoral candidate in feline behavior at the University of Adelaide, in the science magazine “The Conversation.” “They may like the taste, but milk is likely to cause discomfort and health issues for your furry friend, so it’s best to avoid it altogether. And if you think your cat is one of the few lucky ones without lactose intolerance, you’re mistaken.”

According to Henning, cats are very good at hiding their discomfort because, in the wild, showing weakness would make them a target for predators. “If you must, opt for lactose-free milk or milk specifically made for cats, and only give it occasionally as a treat. While it doesn’t cause the same stomach upsets as regular cow’s milk, it also doesn’t provide any nutritional value to your cat.”

Henning also advises against milk alternatives like oat, soy, or almond milk. “Any unusual additions to your cat’s diet can lead to digestive issues, so these should also be avoided.” Henning concludes: “Don’t give your cat milk. They don’t need it, they probably can’t digest it, and it likely causes more pain than it’s worth.”