Isopropyl alcohol (isopropanol, 2-propanol, propan-2-ol) is commonly used as a disinfectant, antifreeze, and solvent, and typically comprises 70 percent of "rubbing alcohol." People ingest isopropyl alcohol to become intoxicated (ie, ethanol substitute) or to harm themselves. When ingested, isopropyl alcohol functions primarily as a central nervous system (CNS) inebriant and depressant, and its toxicity and treatment resemble that of ethanol.
Fatality from isolated isopropyl alcohol toxicity is rare, but can result from injury due to inebriant effects, untreated coma with airway compromise, or rarely, cardiovascular depression and shock following massive ingestion. Supportive care can avert most morbidity and mortality. It is important to differentiate isopropyl alcohol poisoning from methanol and ethylene glycol, which are more dangerous. Isopropyl alcohol does NOT cause an elevated anion gap acidosis, retinal toxicity (as does methanol), or renal failure (as does ethylene glycol). (See 'Differential diagnosis' below.).
This topic review will discuss the diagnosis and management of isopropyl alcohol intoxication. A summary table to facilitate emergency management is provided (table 1). Discussions of other toxic alcohols and a general approach to the poisoned patient are found elsewhere. (See "Ethanol intoxication in adults" and "Methanol and ethylene glycol poisoning" and "General approach to drug poisoning in adults" and "Approach to the child with occult toxic exposure".)
PHARMACOLOGY AND TOXICOLOGY
Isopropyl alcohol is a sedative-hypnotic agent whose toxicity closely resembles that of ethanol, with which it shares strong structural similarity. Like ethanol, isopropyl alcohol's precise mechanism of action in the central nervous system (CNS) remains uncertain. Changes in membrane fluidity and/or function, and interactions with neurotransmitter receptors, are believed to account for the CNS effects of alcohols and other simple hydrocarbons. There is a linear relationship between the molecular weight of alcohols and their sedative effects: as size increases so does sedation. Thus, isopropyl alcohol is marginally more potent than ethanol at comparable concentrations.
In untreated animals, the median lethal dose lies between 4 and 8 g/kg. Many sources estimate the lethal dose to be 250 mL in humans (eg, less than 400 mL of a 70 percent solution). It is important to recognize that, with treatment, adults and children have survived much larger ingestions [1,2].