Antifreeze poisoning is a very serious illness which occurs when animals consume antifreeze which contains ethylene glycol. Most cases of antifreeze poisoning are seen in dogs and cats, but this can also occur in humans, most classically in curious children who drink antifreeze because it tastes good. People and pets with antifreeze poisoning need immediate medical attention and prompt intervention, or they will die.

Ethylene glycol has a naturally sweet flavor, which makes the taste of engine coolant appealing. Animals may lap up antifreeze because they like the flavor, or because they are thirsty, and because animals are extremely sensitive to ethylene glycol, they can even die from licking antifreeze off their paws after walking through a puddle of it. Children are also very sensitive, especially if they are small. If consumption of antifreeze is suspected, the patient should be taken for immediate testing and medical care.

The poisoning is caused by the metabolism of ethylene glycol in the liver, which breaks the chemical down into dangerous compounds which interfere with the function of the central nervous system. In the early stages, antifreeze poisoning causes a drunken appearance, which slowly develops into more serious symptoms, including vomiting, frequent urination, extreme thirst, confusion, dizziness, listlessness, convulsions, abdominal tenderness, and eventual death.

Even when antifreeze poisoning is caught and treated successfully, it can cause long term damage to the kidneys and to the extremities. Some animals who have survived have lost extremities such as ears and limbs because the damage from the poisoning has been so extensive, and antifreeze poisoning can also cause brain damage.

Treatment relies on getting the ingested antifreeze out of the body. Vomiting is sometimes induced, and patients can also be given drugs which will inhibit the metabolism of ethylene glycol in the liver. In fact, one of the best treatments is regular ethanol. In addition, hemodialysis may be used to clean the blood.

People should be very careful when handling engine coolant, and they should avoid leaving even small spills. When coolant is changed, it should be collected in a container which can be sealed and disposed of, and any spills should be wiped up or washed away. People can substantially reduce the risks by using coolant with a bittering agent which makes the antifreeze unpalatable, or by using antifreeze made with propylene glycol, which is not nearly as toxic. Confining children and animals so that they cannot ingest antifreeze when they roam is also advisable.