Poisoning can happen when a cat eats something, gets a substance on its fur and licks it off, or is exposed to an unsuitable product on its skin. Cats have particular limitations in how they break down certain medicines and chemicals, which means that ordinary household products can pose a significant risk.
Find out what your cat may have been exposed to and keep the packaging or product name. If something has got onto the fur, stop your cat from licking itself while you contact a vet for instructions. Signs can include drooling, vomiting, wobbliness, trembling, lethargy or effects on breathing, but some poisons cause delayed signs.
Call a vet right away if you suspect a toxic exposure. Do not give medicines, milk or other remedies of your own, and do not try to make your cat vomit at home. The right first step depends entirely on the substance your cat has been exposed to.