The image of a cat lapping up a saucer of milk is one of the most persistent — and misleading — images in popular culture. The reality is more complicated: most adult cats are lactose intolerant, and drinking regular cow’s milk can cause digestive problems ranging from mild discomfort to significant illness.
Are Cats Lactose Intolerant?
Yes — the majority of adult cats are. Here’s why.
Kittens produce an enzyme called lactase that breaks down lactose, the sugar found in milk. This allows them to digest their mother’s milk during the first weeks of life. As kittens wean (typically between 4–8 weeks), their bodies gradually stop producing lactase. By adulthood, most cats can no longer break down lactose efficiently.
When a lactose-intolerant cat drinks milk, the undigested lactose passes into the large intestine where bacteria ferment it, producing gas and drawing water into the gut. The result: bloating, stomach cramps, diarrhoea, and general digestive distress. Not every cat will react the same way — some tolerate small amounts — but the risk is real for most. For more on this topic, see our detailed article on whether cats are lactose intolerant.
Can Cats Drink Cow’s Milk?
Cow’s milk is particularly high in lactose compared to cat’s milk. A tablespoon as an occasional treat probably won’t cause harm for most cats, but regular feeding is a bad idea. Even cats that don’t show obvious symptoms may experience low-grade inflammation in the gut that affects nutrient absorption over time.
Symptoms of Milk Intolerance in Cats
- Diarrhoea or loose stools within 8–12 hours of drinking milk
- Vomiting
- Stomach bloating or rumbling
- Gas
- Decreased appetite
If your cat shows these symptoms after drinking milk, it confirms what their biology is telling you: they can’t process it properly.
Can Cats Drink Lactose-Free Milk?
Lactose-free cow’s milk removes the lactose problem, but it’s still not ideal. It contains calories, fats, and proteins that aren’t balanced for a cat’s nutritional needs. It won’t cause the digestive upset that regular milk does, but it shouldn’t be a regular part of your cat’s diet.
Purpose-made “cat milk” (available from brands like Whiskas and KitCat in South Africa) is lactose-free and formulated to be safer for cats. It’s fine as an occasional treat — but it’s still extra calories that can contribute to weight gain if offered regularly.
Can Cats Drink Almond Milk or Oat Milk?
Plant-based milks don’t contain lactose, so they won’t trigger the same digestive issues. However:
- Almond milk: Generally safe in tiny amounts but offers no nutritional benefit to cats. Some brands contain added sugar or sweeteners (including xylitol, which is toxic to pets) — always check the label.
- Oat milk: Not toxic, but high in carbohydrates that cats don’t need. Cats are obligate carnivores — their digestive system is designed for animal protein, not plant-based foods.
- Soy milk: Some cats tolerate it, others don’t. Soy is a common allergen in cats, so introduce cautiously if at all.
- Coconut milk: High in fat. Small amounts are unlikely to cause harm, but it’s not nutritionally appropriate for regular consumption.
The bottom line: no type of milk — animal or plant-based — is necessary for a cat’s diet. Fresh water is the only liquid your cat needs.
What Should Cats Drink Instead?
Water. Always water. A cat’s hydration needs are straightforward:
- Provide fresh, clean water in a wide, shallow bowl (many cats dislike narrow bowls because their whiskers touch the sides).
- Place water bowls away from food — cats instinctively prefer to drink away from where they eat.
- Consider a cat water fountain. Many cats prefer running water, and a fountain encourages them to drink more.
- If your cat eats dry food exclusively, hydration is especially important. Wet food naturally provides some moisture; dry food doesn’t.
If you’re concerned your cat isn’t drinking enough, adding a small amount of water to their wet food or offering ice cubes to bat around can increase intake.
Why Do Cats Love Milk If It’s Bad for Them?
Cats are attracted to the fat content in milk, not the lactose. Cow’s milk is rich in animal fat, which tastes appealing to an obligate carnivore. It’s the same reason a cat will lick butter, cream, or cheese — they’re drawn to the fat, not the dairy itself.
This is also why the cultural image of cats and milk persists. For centuries, farm cats drank milk because it was available and they clearly enjoyed it. The digestive consequences happened quietly, out of sight, and weren’t connected to the milk in people’s minds.
The Verdict
Can cats drink milk? Technically yes — a small amount won’t kill them. Should they? No, not regularly. The digestive risks outweigh the minimal enjoyment, and there’s no nutritional benefit. If you want to give your cat a liquid treat, use purpose-made cat milk or a small amount of the water from a tin of tuna (in spring water, not brine).
For more on what your cat should and shouldn’t eat, read our guide to what cats like to eat and our cat food essentials.
