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  Consider toxic alcohol poisoning in cases of an unexplained anion gap acidosis or an elevated osmol gap.

  
  
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  Focus your initial treatment on the early inhibition of alcohol dehydrogenase (ADH) in cases of ethylene glycol or methanol poisoning to prevent the accumulation of toxic metabolites.

  
  
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  Consult your local poison center (800-222-1222) or local toxicologist in all suspected cases for help initiating antidotal therapy and obtaining confirmatory toxic alcohol levels.

  
  
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  Consult a nephrologist early to prepare for hemodialysis in cases involving large ingestions or severe metabolic acidosis.

With the exception of ethanol, no other alcohols are safe for human consumption and are therefore considered toxic alcohols. Ethylene glycol, methanol, and isopropanol are the most common toxic alcohols associated with human poisoning. Toxic alcohols are often ingested in 1 of 2 ways, either unintentionally if placed in an inappropri–ately labeled container, or intentionally by patients either attempting suicide or trying to become intoxicated when regular ethanol is not readily available. Of note, each of the 3 is capable of causing inebriation, with isopropanol being twice as intoxicating as ethanol.

According to the National Poison Data System, more than 35,000 toxic alcohol exposures are reported to the American Association of Poison Control Centers yearly. Isopropanol is the most frequently ingested but causes the fewest number of deaths, whereas methanol is the least commonly ingested toxic alcohol but associated with the highest number of fatalities.

Although the parent compound is responsible for inebriation, toxicity results from the metabolism of these compounds via alcohol dehydrogenase (ADH) into toxic organic acid byproducts with consequent end organ injury. Ethylene glycol is metabolized to glycolic acid, glyoxylic acid, and oxalic acid, all of which can produce systemic acidosis and acute kidney injury. Methanol is converted to formic acid which can produce systemic acidosis and retinal toxicity. Isopropanol is not converted to an organic acid but is rather metabolized into acetone, which can produce hemorrhagic gastritis and systemic hypotension in the absence of a concurrent acidosis. If either are unrecognized or untreated, all toxic alcohol ingestions can result in patient fatality.

History

Obtaining a history of toxic alcohol ingestion is often challenging. Patients may be obtunded on arrival to the emergency department (ED), not forthcoming with the ingestion history, or too young to be appropriately descriptive (children). Reading the ingredient lists on the labels of any empty bottles found at the scene or brought to the ED can be extremely helpful. If a bottle or label is not available, ask the patient what kind of product was ingested. For example, antifreeze usually contains ethylene glycol, windshield-washing fluid usually contains metha–nol, and rubbing alcohol usually contains isopropanol. That said, remember that some products may contain different types of toxic alcohols (eg, some gas-line antifreeze products contain methanol). Beyond attempting to identify exactly what was ingested, it is critically important to determine the time of ingestion, as this will affect the interpretation of laboratory results and impact patient management priorities.

Physical Examination

Most patients poisoned with a toxic alcohol will demonstrate some level of central nervous system (CNS) depression analogous to inebriation. Patients arriving soon after an ingestion may appear well with unremarkable physical exams, whereas those who arrive many hours after ingestion may be obtunded with unstable vital signs. Of note, the peak serum level of a toxic alcohol correlates poorly with the physical exam findings. As with all overdoses, perform a careful neurologic examination (mental status, cranial nerves, cerebellar findings, and motor strength). Ocular examination may reveal blurred vision, decreased visual acuity, retinal edema, optic atrophy, or hyperemia of the optic disc in methanol poisoning. Abdominal tenderness or blood on rectal examination may indicate isopropanol ingestion as it is classically associated with hemorrhagic gastritis.