Ethylene glycol poisoning is treated by blocking the body’s conversion of ethylene glycol into toxic byproducts, primarily using an antidote called fomepizole. In severe cases, hemodialysis is used to physically remove the poison from the blood. The mortality rate ranges from 1% to 22% depending on how much was ingested and how quickly treatment begins, so speed is the most important factor in outcomes.
Why Ethylene Glycol Becomes Dangerous
Ethylene glycol itself is relatively harmless. The danger comes from what your body turns it into. An enzyme called alcohol dehydrogenase breaks ethylene glycol down into a series of increasingly toxic compounds. The first major one, glycolate, is primarily responsible for the severe acid buildup in the blood that makes this poisoning so dangerous. Glycolate is then further converted into oxalate, which binds with calcium and forms sharp crystals that deposit in the kidneys and other tissues. These calcium oxalate crystals, which appear in urine as distinctive diamond-shaped structures, can cause permanent kidney damage.
This metabolism is the key to understanding every part of treatment. If you can stop alcohol dehydrogenase from processing ethylene glycol, the compound stays in its original, relatively harmless form and is eventually filtered out by the kidneys or removed through dialysis.
How Symptoms Progress Over Time
Ethylene glycol poisoning unfolds in three overlapping stages, though not every person experiences all three, and the progression isn’t always predictable.
The first stage begins within 30 minutes to 12 hours after ingestion. It primarily affects the nervous system, producing symptoms that look a lot like alcohol intoxication: confusion, slurred speech, nausea, vomiting, and loss of coordination. Because ethylene glycol has a sweet taste and these early symptoms mimic drunkenness, poisoning can go unrecognized during this critical treatment window.
The second stage, involving the heart and lungs, typically appears between 12 and 24 hours. Rapid breathing, elevated heart rate, and in serious cases, fluid buildup in the lungs can develop as the body struggles with worsening acid levels in the blood.
The third stage hits the kidneys between 24 and 72 hours after ingestion, as calcium oxalate crystals accumulate in kidney tissue. This is when acute kidney failure occurs. Blood levels above 50 mg/dL have traditionally been associated with significant toxicity, and severe cases can drive blood pH below 7.0, a life-threatening degree of acidosis.
Fomepizole: The Primary Antidote
Fomepizole works by competing with ethylene glycol for access to alcohol dehydrogenase. It binds to the enzyme far more effectively than ethylene glycol does, essentially shutting down the production of toxic metabolites. When given early, before significant metabolism has occurred, fomepizole can prevent the cascade of organ damage entirely.
Treatment begins with a loading dose of 15 mg/kg of body weight, given either intravenously or by mouth. This is followed by doses of 10 mg/kg every 12 hours for the first 48 hours. After that, the dose increases back to 15 mg/kg every 12 hours for any remaining treatment time. Therapy continues until ethylene glycol blood levels drop below 30 mg/dL. The American Academy of Clinical Toxicology recommends fomepizole as the preferred antidote for early-stage ethylene glycol poisoning.
Fomepizole’s main advantage over the older alternative (intravenous ethanol) is its predictability. It doesn’t require constant blood level monitoring, doesn’t cause intoxication, and is far easier for medical teams to manage. It is, however, expensive and not available in every country or hospital.
Intravenous Ethanol as a Backup
When fomepizole isn’t available, intravenous ethanol serves as the alternative antidote. The principle is identical: ethanol also competes for alcohol dehydrogenase, blocking ethylene glycol metabolism. The target blood ethanol level is 100 to 150 mg/dL, which is enough to effectively prevent the formation of toxic byproducts.
Ethanol therapy is significantly harder to manage. Blood ethanol levels fluctuate and require frequent monitoring. The patient becomes genuinely intoxicated, which complicates neurological assessments and can cause its own complications, including low blood sugar and sedation. It also typically requires ICU-level monitoring. For these reasons, fomepizole has largely replaced ethanol where it’s available.
When Hemodialysis Is Needed
Antidotes alone aren’t always enough. Hemodialysis physically removes both ethylene glycol and its toxic metabolites from the blood, and it’s indicated in cases of severe acidosis or kidney dysfunction. If significant metabolism has already occurred by the time treatment starts, the damage is being driven by metabolites already circulating in the blood, and no amount of enzyme-blocking will reverse that. Dialysis clears those metabolites directly.
Hemodialysis is typically considered when blood pH drops dangerously low, when kidney function is deteriorating, or when ethylene glycol levels are very high. It also corrects the electrolyte imbalances that accompany severe poisoning, including dangerously low calcium levels caused by oxalate binding. During dialysis, fomepizole dosing needs to be adjusted because dialysis removes fomepizole from the blood as well.
Correcting Acid Buildup in the Blood
Severe ethylene glycol poisoning causes profound metabolic acidosis as glycolate accumulates. In critical cases, the blood becomes so acidic that organ systems begin to fail. Intravenous sodium bicarbonate is used to counteract this, with the goal of raising blood pH to 7.30 or higher. This buys time while antidotes and dialysis work to eliminate the underlying cause. Correcting the acidosis also helps protect the heart, which becomes increasingly irritable and prone to dangerous rhythms as pH drops.
Supportive Treatments
Beyond the core interventions of antidotes, dialysis, and bicarbonate, several supportive measures play a role. Thiamine (vitamin B1) and pyridoxine (vitamin B6) are commonly given because they help shunt glycolate metabolism toward less toxic pathways. Rather than allowing glycolate to become oxalate, these vitamins support alternative enzymatic routes that produce less harmful end products.
Calcium may need to be replaced intravenously if oxalate has bound enough circulating calcium to cause dangerously low levels, which can trigger seizures and cardiac problems. Fluid resuscitation helps maintain kidney perfusion and supports the body’s ability to clear toxins.
Why Timing Determines Everything
The single biggest factor in surviving ethylene glycol poisoning is how quickly treatment begins relative to ingestion. In the study that reported a 1% to 22% mortality range, the patients who died had delays of 6 to more than 24 hours between ingestion and hospital arrival, and some had consumed up to 500 mL. When fomepizole is given before significant metabolism has occurred, patients can recover with little or no organ damage because the ethylene glycol is simply excreted unchanged.
Once toxic metabolites have formed and crystals have deposited in the kidneys, the damage becomes partially irreversible. Some patients who survive late-stage poisoning require temporary or even permanent dialysis due to kidney damage. Early recognition of the symptoms, particularly unexplained intoxication with worsening acidosis in someone with access to antifreeze or industrial solvents, is what makes the difference between a straightforward recovery and a life-threatening emergency.