Antifreeze poisoning: what to do

Why antifreeze is dangerous

Most automotive antifreeze is based on ethylene glycol, which the body metabolizes into toxic compounds that can damage the kidneys, brain and other organs. Propylene glycol products are considerably less toxic but still shouldn't be swallowed (see EG vs PG). Treat any ingestion as an emergency.

Symptoms (people and pets)

Symptoms can seem to improve before getting worse. Don't rely on how the person or animal looks. Seek care immediately.

What to do immediately

1. Call emergency services or a poison center (US: 1-800-222-1222). For pets, call a vet or animal poison line.
2. Don't induce vomiting unless a professional tells you to.
3. Have the container or label ready.
4. Follow the professional instructions.

Prevention checklist

• Store antifreeze sealed, labelled and out of reach.
• Never put it in drink bottles.
• Wipe up drips and spills immediately.
• Fix leaks. See coolant leak.
• Dispose of used coolant properly. See disposal.

Why pets are especially at risk

Ethylene glycol tastes sweet, and animals, especially dogs and cats, may lap up puddles or drips in driveways and garages. Cats are particularly sensitive. Because early signs can be subtle, owners may not realise an animal was exposed until it's seriously ill. If you know or suspect exposure, don't wait for symptoms. Contact a vet immediately, because treatment is most effective early.

Accidental exposure: skin and eyes

Skin contact with coolant is far less dangerous than swallowing it, but wash it off with soap and water and remove contaminated clothing. For eye contact, rinse with clean water for several minutes and seek medical advice if irritation persists. The product SDS includes specific first-aid instructions for skin, eye and inhalation exposure.

Safer coolant choices around the home

Some coolants are based on propylene glycol, which is considerably less toxic than ethylene glycol, though still not safe to swallow. Some EG coolants include a bittering agent to discourage ingestion. Neither replaces careful storage and cleanup. Always use the coolant your vehicle specifies. See the EG vs PG guide before considering a switch.

Workplace and garage safety

• Label all containers clearly, including used coolant.
• Keep drain pans covered or emptied promptly.
• Keep children and pets away from work areas.
• Have absorbent material ready for spills.
• Post poison center numbers where fluids are handled.

How ethylene glycol harms the body

According to Poison Control (poison.org), for several hours after someone swallows antifreeze they may seem fine while the body breaks ethylene glycol down into by-products that affect blood chemistry, the nervous system and the kidneys. CDC/ATSDR guidance describes how unmetabolized ethylene glycol causes an alcohol-like intoxication, while its metabolites (including glycolic and oxalic acids) cause severe metabolic acidosis and can damage the brain, heart and kidneys. Calcium oxalate crystals can deposit in the kidneys, and ATSDR notes kidney failure can occur within 24 to 28 hours.

MedlinePlus states that as little as 120 mL (about 4 fluid ounces) of ethylene glycol may be enough to kill an average-sized man. Smaller amounts can be dangerous for children. This is why poison centers say not to wait for symptoms.

Emergency contacts (US)

Outside the US, use your local emergency number or national poison center.

What happens at the hospital

MedlinePlus describes diagnosis through blood and urine tests, including blood gases, osmolality and ethylene glycol levels, and treatments that can include an antidote (fomepizole) that slows the formation of the poisonous by-products, intravenous sodium bicarbonate for acidosis and, in severe cases, dialysis. Ethanol may be used if fomepizole is unavailable. Outcomes are better when treatment starts early, which is the strongest reason to seek help immediately.

Pets: timing matters

The ASPCA notes that problems may start within a couple of hours, early signs may be missed, and pets may be markedly ill within six to twelve hours. Signs include unsteadiness, vomiting, depression, increased thirst and urination, loss of appetite and seizures. The Merck Veterinary Manual describes the lethal dose as small (3 to 4 teaspoons in dogs and 1 to 2 teaspoons in cats), and says severe kidney failure usually develops within 36–72 hours in dogs and 12–24 hours in cats. Take the product packaging to the vet if you can.

Both the ASPCA and Merck note that propylene glycol antifreezes have a wider safety margin, though they're still not harmless.

Hidden sources of ethylene glycol at home

• Car coolant and drips under vehicles
• Some products used to winterize toilets and plumbing (check the label)
• Bases of portable basketball hoops (cited by the ASPCA)
• Snow globes and some inks or paints (cited by the ASPCA)

Eye and skin exposure

ATSDR notes ethylene glycol is only mildly irritating to skin and isn't absorbed well through the skin or by inhalation. For eyes, NNEPC advises flushing with warm water for 10–15 minutes and calling the poison center for guidance.

Myths

• "If they seem fine, they're fine." Poison Control notes people can seem fine for hours.
• "Make them vomit." Only on professional advice.

Key numbers

• US Poison Help: 1-800-222-1222
• ASPCA Animal Poison Control: (888) 426-4435
• Emergency: 911 (US)

Sources

1. Poison Control (poison.org): Antifreeze, bad for your kids and pets
2. CDC/ATSDR: Ethylene glycol medical management guidelines
3. MedlinePlus: Ethylene glycol poisoning
4. Northern New England Poison Center: Ethylene glycol (antifreeze)
5. ASPCA: Dangers of antifreeze and your pets
6. ASPCA Animal Poison Control
7. Merck Veterinary Manual: Ethylene glycol poisoning