Is antifreeze toxic to cats? What to do now

Is antifreeze toxic to cats?

Yes, and it is one of the most dangerous poisons a cat can meet. Antifreeze usually contains ethylene glycol, which tastes sweet, and as little as a teaspoon can be fatal to a cat. The antidote only works if it is given within about three hours, before the kidneys are damaged. Go to a vet now if there is any chance your cat drank or licked it, even if it looks well.

Written by the Pativo team · Updated 14 November 2026

General information, not veterinary advice. If your pet may have eaten this, contact a vet now; do not wait for signs.

Go to an emergency clinic now if

Your cat may have drunk or licked antifreeze, coolant, de-icer or brake fluid

Antifreeze was spilled where your cat walks and it has wet paws

Your cat seems drunk, wobbly or disoriented

Vomiting with heavy drinking and urinating

Your cat seemed ill earlier and now seems better: this is not recovery

Who to call

Your own vet first. If they are closed, the nearest emergency or out-of-hours clinic.

In the United States

Both answer 24 hours a day and may charge a consultation fee.

How Pativo rates this

Go now, whatever the amount

1Nothing alarmingWatch at home

2Worth watchingMonitor for a few days

3See a vet soonWithin 48 hours

4See a vet todayWithin 24 hours

5EmergencyGo now

This is the level the app answers with before it knows the amount. It comes from the app's own poison list, which runs on your phone.

Signs to watch for

Sign	Usually starts
Seems drunk: wobbling, stumbling, disoriented	30 minutes to 12 hours
Vomiting, drooling	30 minutes to 12 hours
Excessive thirst and urination	30 minutes to 12 hours
Brief apparent improvement	Around 12 hours
Kidney failure: little or no urine, not eating, mouth ulcers	12-24 hours in cats
Seizures, coma	12-24 hours onwards

Why is antifreeze so dangerous to cats?

Ethylene glycol itself is only mildly toxic; the danger comes from what the liver turns it into. Within hours it is broken down into acids that upset the blood chemistry and into oxalate, which forms crystals that destroy the kidneys. The antidote works by blocking that breakdown, so it only helps while unprocessed ethylene glycol is still in the body.

Concentrated antifreeze can contain up to 95% ethylene glycol, and ready-mixed coolant around 50%. It is also found in some brake fluids and de-icers. Not every antifreeze contains it, so check the label.

How much antifreeze can kill a cat?

Very little. The Merck Veterinary Manual gives the minimum lethal dose for cats as 1.4 ml of undiluted ethylene glycol per kg of body weight. For a 4 kg cat that is about 5.6 ml, roughly one teaspoon, which matches the Pet Poison Helpline's warning that as little as one teaspoon can be fatal. Diluted coolant takes about twice as much, which is still only a few laps from a puddle.

Why does timing matter so much?

Cats need treatment within about three hours of drinking antifreeze for the antidote to work, according to the Pet Poison Helpline; dogs have longer, about 8 to 12 hours. In cats, kidney failure can start 12 to 24 hours after drinking. Merck warns that once a cat's kidneys are failing, blocking the breakdown of ethylene glycol offers little benefit because most of it has already been converted, and the outlook becomes guarded to poor.

There is also a trap. Around 12 hours after the first drunk-like signs, many cats seem to improve. This is the poison moving from the bloodstream to the kidneys, not recovery.

What will the vet do?

The vet will usually test the blood if a test is available, but start treatment on the history alone if waiting would cost time. Treatment combines an antidote given into a vein, intravenous fluids, correction of the blood chemistry and repeated kidney checks. Cats that arrive after kidney failure has begun may need dialysis, which few hospitals offer, and many do not survive.

What should I tell the vet?

Tell the clinic the product name and whether it says ethylene glycol on the label, whether it was concentrated or ready-mixed, roughly how much could be missing, and the earliest time your cat could have reached it. Mention any wobbling or vomiting you saw, even if it has stopped. If you are not sure your cat drank any, say so: vets would rather treat a possible exposure than miss the three-hour window.

How do I stop it happening again?

Store antifreeze and coolant in sealed containers on a high shelf, clean up spills straight away with plenty of water, and fix leaking radiators. When topping up a car, keep cats indoors and check the ground afterwards. Dogs face the same risk with a longer window; see antifreeze poisoning in dogs.

Questions owners ask

Why would a cat drink antifreeze?

Ethylene glycol tastes sweet and is often found in puddles under cars or in open containers. Some products now contain a bittering agent, but they can still be swallowed.

Can a cat be poisoned by walking through antifreeze?

Yes. Cats groom their paws and coat, and the Merck Veterinary Manual notes that ethylene glycol absorbed through the skin from topical products has also poisoned cats.

Is there a test for antifreeze poisoning?

Some clinics have a quick blood test, but it is only reliable within a limited time after drinking. Vets often start treatment based on the history alone rather than wait.