Ingesting isopropyl alcohol (isopropanol), commonly known as rubbing alcohol, causes intoxication similar to drinking alcohol (ethanol). Isopropanol is significantly more toxic and possesses a potency two to three times greater than ethanol, making even small amounts extremely hazardous. This substance is widely available in household products, antiseptics, and hand sanitizers, and should never be consumed for inebriation. While initial effects may feel like drunkenness, the chemical consequences rapidly lead to severe, life-threatening poisoning.
Chemical Distinction and Metabolic Pathway
The difference between isopropanol and ethanol lies in how the body processes them. Both compounds are metabolized in the liver by the enzyme alcohol dehydrogenase, but their resulting byproducts dictate the severity of the poisoning. Ethanol is converted into acetaldehyde, which is then quickly broken down into relatively harmless acetic acid.
Isopropanol follows a different metabolic path, converting directly into acetone, which is the same chemical found in nail polish remover. Acetone is a ketone body that the body cannot easily eliminate and is responsible for the prolonged and severe toxicity associated with isopropanol ingestion.
Unlike the short-lived half-life of ethanol’s initial metabolite, acetone’s half-life in the bloodstream can range from 7.7 to 27 hours. This prolonged presence of acetone leads to continuous and deep central nervous system (CNS) depression. The slow elimination of this metabolite turns intoxication into a medical emergency.
The Immediate Central Nervous System Effects
The initial intoxicating effects of isopropanol occur rapidly because the substance is a potent central nervous system (CNS) depressant. Isopropanol is absorbed very quickly, with peak blood concentrations often reached within 30 minutes of ingestion. This rapid absorption contributes to the swift onset of impairment, mimicking the initial stages of ethanol intoxication.
A person who has ingested isopropanol will quickly exhibit signs like slurred speech, dizziness, uncoordinated movement, and mental confusion. Due to its higher lipid solubility compared to ethanol, isopropanol crosses the blood-brain barrier more effectively, making it a more powerful intoxicant per unit volume. As the concentration rises, this initial stupor can quickly progress to a deep and unresponsive state.
Clinical Signs of Isopropyl Alcohol Poisoning
The clinical presentation of isopropanol poisoning is marked by severe symptoms resulting from the combined effects of isopropanol and its acetone metabolite. One of the most dangerous signs is profound CNS depression, which can rapidly lead to a deep coma and respiratory failure. The powerful CNS depression suppresses the body’s drive to breathe.
Isopropanol is also a direct irritant to the gastrointestinal tract, frequently causing severe abdominal pain, nausea, and vomiting that may contain blood, a condition known as hemorrhagic gastritis. A distinctive laboratory finding is an elevated osmolal gap along with ketosis, meaning high levels of ketones (acetone) are present, but without the severe metabolic acidosis seen in other toxic alcohol poisonings like methanol.
The presence of high acetone levels in the blood is often detectable by a characteristic sweet or fruity odor on the patient’s breath. Furthermore, ingestion can lead to severe hypotension, a sign of circulatory collapse associated with increased mortality.
Emergency Action and Treatment
If ingestion of isopropyl alcohol is suspected, immediate action is necessary because of the rapid onset of toxicity. The first step is to call a local emergency number, such as 911, and the national Poison Help hotline (1-800-222-1222) for expert guidance.
Attempting to induce vomiting or administer home remedies is strongly discouraged, as this can worsen the patient’s condition or lead to aspiration into the lungs. Medical treatment focuses on supportive care, including maintaining a patent airway and supporting cardiovascular function. This may involve mechanical ventilation if breathing is suppressed and administering intravenous fluids to manage blood pressure.
While some toxic alcohol ingestions require specific antidotes, isopropanol poisoning is primarily managed with supportive measures. In the most severe cases involving persistent hypotension or extremely high blood concentrations, a procedure called hemodialysis may be used to filter the isopropanol and acetone directly from the bloodstream. Patients are monitored closely until the isopropanol and acetone levels have dropped sufficiently and clinical sobriety has returned.