Can Cats Drink Milk?

Updated 18 October 2026 · Researched against PDSA, Cats Protection and International Cat Care guidance

Kittens produce lactase to digest their mother's milk. After weaning, production falls, and most adult cats end up lactose intolerant. Cow's milk is also richer in lactose than cat milk, so a saucer often ends in loose stools and stomach upset.

There is no nutritional reason to give cow's milk to an adult cat. Cats get their water from food and from drinking; a bowl of fresh water is the correct offering. If a kitten genuinely needs milk, that is a veterinary decision about a kitten milk replacer — never cow's milk.

What to watch for in the UK

• Lactose-free 'cat milk' products are lower risk but still unnecessary calories.
• Never give cow's milk to a kitten instead of a proper milk replacer.
• Milk left out in warm weather grows bacteria quickly — another reason not to leave saucers down.
• If your cat suddenly starts drinking a lot more water, that is a health sign, not a milk question.

If your cat has already eaten it

1. A saucer: expect loose stools for a day; offer water.
2. Persistent diarrhoea, vomiting or a cat that stops eating: phone your vet.

Out of hours, use your practice's emergency number. If you can, take the packaging with you — the ingredient list often tells the vet more than the description does. This page explains risk; it cannot diagnose your cat, and it deliberately contains no doses or home treatments.

If your cat is already vomiting, see the cat vomiting guide and vomiting blood. For the wider red-flag checklist, use sick cat symptoms. If a plant rather than a food is involved, the toxic plants checklist is the right page.

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