Antifreeze is a liquid that prevents the radiator in cars from freezing or overheating. It’s also known as engine coolant. Although water-based, antifreeze also contains liquid alcohols like ethylene glycol, propylene glycol, and methanol.

Propylene glycol is also an ingredient in some foods and cosmetics. It isn’t considered harmful in small amounts, according to the Agency for Toxic Substances and Disease Registry (ATSDR).

On the other hand, ethylene glycol and methanol are hazardous and poisonous if ingested.

It only takes a small amount of antifreeze to poison the human body and cause life-threatening complications.

There are different explanations for why someone might ingest antifreeze. One reason is intentional self-harm. But it’s also possible to accidentally drink the chemical. This can happen when antifreeze is poured into a glass or another type of drink container and mistaken for a beverage. Given this possibility, it’s important to recognize symptoms of antifreeze poisoning.

Antifreeze poisoning can happen gradually over several hours, so you may not have symptoms immediately after ingesting the chemical. If you feel fine, you may even brush off the incident as nothing more than a close call. But the situation isn’t that simple.

As your body absorbs or metabolizes antifreeze, the chemical is converted into other toxic substances such as:

  • glycolaldehyde
  • glycolic acid
  • glyoxylic acid
  • acetone
  • formaldehyde

Your body slowly begins to react to the antifreeze in your system. The time it takes for the first symptom to appear varies. It depends on the amount swallowed.

The earliest symptoms can develop 30 minutes to 12 hours after ingestion, with the severest symptoms starting about 12 hours after ingestion, according to the ATSDR. Early symptoms of antifreeze poisoning may include an inebriated feeling. Other early symptoms include:

  • headache
  • fatigue
  • lack of coordination
  • grogginess
  • slurred speech
  • nausea
  • vomiting

As your body continues to break down the antifreeze over the next several hours, the chemical can interfere with your kidney, lung, brain, and nervous system function. Organ damage can occur 24 to 72 hours after ingestion.

You may also develop:

  • rapid breathing
  • an inability to urinate
  • rapid heartbeat
  • convulsions

It’s possible to lose consciousness and fall into a coma.

Get immediate help if you or another person ingests antifreeze. It doesn’t matter if it was only a small amount. The sooner you get help, the better the outcome.

If you feel fine and you’re not sure if you ingested antifreeze, you can call Poison Control and speak with a poison specialist for further instructions. The national toll-free number in the United States is 800-222-1222.

But if you’re certain that you’ve ingested antifreeze or you’re showing symptoms of antifreeze poisoning, call 911 immediately.

Suicide prevention

If you think someone is at immediate risk of self-harm or hurting another person:

  • Call 911 or your local emergency number.
  • Stay with the person until help arrives.
  • Remove any guns, knives, medications, or other things that may cause harm.
  • Listen, but don’t judge, argue, threaten, or yell.

If you or someone you know is considering suicide, get help from a crisis or suicide prevention hotline. Try the National Suicide Prevention Lifeline at 800-273-8255.

Once you arrive at the hospital, tell the doctor:

  • what you ingested
  • the time you swallowed it
  • the amount you ingested

The hospital will closely monitor your condition. This is because antifreeze can affect different parts of your body. A doctor or nurse may check your blood pressure, body temperature, breathing rate, and heart rate. They may perform a variety of tests to check the level of chemicals in your bloodstream as well as your organ function. These tests might include:

  • blood tests
  • urine test
  • chest X-ray
  • CT scan to get images of your brain
  • electrocardiogram, which measures the electrical activity in your heart

If you’ve ingested antifreeze, your doctor will begin treatment even if you’re not showing symptoms or only showing mild symptoms.

An antidote is the first line of treatment for antifreeze poisoning. These include either fomepizole (Antizol) or ethanol. Both drugs can reverse the effects of the poison and prevent further problems, such as permanent organ damage.

Even though fomepizole can reverse the effects in about three hours, ethanol is an effective option when fomepizole isn’t available. The hospital may administer this medication intravenously, or through an IV.

If you don’t get immediate help, antifreeze poisoning can decrease kidney function, causing an inability to urinate or low urine output. In the case of poor kidney function, your treatment may also consist of dialysis.

Dialysis is when you’re hooked up to a machine that filters your blood and removes toxins from your bloodstream. Depending on the level of kidney damage, dialysis may be a temporary treatment or a permanent one. If temporary, it may take up to two months to recover kidney function.

If you also experience breathing difficulties due to severe poisoning, the hospital may administer oxygen therapy or sedate you and insert a breathing tube down your mouth into your throat.

Because antifreeze tastes sweet, accidental ingestion can occur. Here are a few prevention tips to keep you and your family — including your pets — safe:

  • Don’t pour antifreeze into water bottles or other containers. Keep the chemical in its original container.
  • If you spill antifreeze while working on your car, clean up the spill and spray down the area with water. This can prevent pets from drinking the fluid.
  • Always put the cap back on antifreeze containers. Keep the chemical out of reach of children and pets.
  • As a precaution, don’t drink any beverage that you don’t recognize. Never accept drinks from a stranger.

With early intervention, medication can possibly reverse the effects of the poisoning. Treatment can prevent kidney failure, brain damage, and other permanent damage to your lungs or heart. If left untreated, severe antifreeze poisoning can be fatal within 24 to 36 hours.

Remember, it only takes a few hours for serious symptoms to develop. Don’t delay treatment.