Rubbing alcohol, or isopropyl alcohol, is a common household product used as a disinfectant and solvent, but it is not safe for internal consumption. This substance is distinct from the ethanol found in alcoholic beverages and is highly toxic when ingested. Rubbing alcohol typically comes in concentrations of 70% or 91%. Swallowing even a small amount can lead to serious poisoning, which requires immediate medical attention.
Defining the Toxic Dose
The amount of isopropyl alcohol that is toxic or potentially lethal varies based on the product’s concentration, the person’s body weight, and their overall health. For an average adult, the estimated toxic oral dose is low, around 0.5 to 1 milliliter of 70% rubbing alcohol per kilogram of body weight. This small quantity can cause severe intoxication and poisoning.
While a lethal dose is not fixed, fatalities have been reported following the ingestion of as little as 240 milliliters (about eight ounces). The high variability means some individuals have survived consuming much larger amounts, even up to one liter. Concentration plays a role, as a 70% solution requires a greater volume to reach the same level of pure isopropanol compared to a 91% solution. Children are at a much higher risk because their smaller body size means a far lower absolute volume can be fatal.
How Isopropyl Alcohol Harms the Body
When ingested, isopropyl alcohol is rapidly absorbed from the gastrointestinal tract, with peak blood levels occurring within an hour. The primary mechanism of harm involves profound depression of the central nervous system (CNS). Isopropyl alcohol is two to three times more potent as a CNS depressant than ethanol, causing severe intoxication at lower concentrations.
The liver metabolizes the ingested isopropanol using the enzyme alcohol dehydrogenase, converting it into a compound called acetone. Acetone is the same chemical found in some nail polish removers and is a ketone body.
Unlike the toxic alcohols methanol and ethylene glycol, acetone is less toxic but remains a potent CNS depressant. Acetone accumulation prolongs the sedative effects of the original alcohol. Because this metabolism creates acetone but not significant organic acids, severe poisoning is characterized by ketosis without metabolic acidosis.
Recognizing the Signs of Poisoning
Ingestion of rubbing alcohol quickly leads to symptoms that resemble severe alcohol intoxication, but the effects are more severe and longer-lasting. One of the earliest signs is profound central nervous system depression, manifesting as slurred speech, uncoordinated movement, stupor, and confusion. This sedation can rapidly progress to unconsciousness, coma, and life-threatening respiratory depression.
The substance is a severe gastrointestinal irritant, causing abdominal pain, nausea, and forceful vomiting. Severe irritation can lead to internal bleeding and vomiting blood. A specific sign of isopropanol poisoning is a fruity odor on the breath, caused by the body excreting the metabolite, acetone, through the lungs. Other serious symptoms include low blood pressure, a rapid heart rate, and hypothermia.
Immediate Steps and Medical Treatment
If ingestion of isopropyl alcohol is suspected, the immediate step is to call an emergency number or Poison Control for guidance. Do not attempt to induce vomiting, as this increases the risk of aspiration into the lungs. While waiting for emergency services, try to keep the person awake and monitor their breathing.
Medical treatment is primarily supportive, focusing on managing the life-threatening effects of central nervous system and respiratory depression. In the hospital, this involves monitoring vital signs, securing the airway, and administering oxygen if breathing is compromised. Intravenous fluids are given to maintain hydration and support blood pressure, which often drops due to vasodilation.
In severe cases, especially those involving persistent low blood pressure or extremely high levels of isopropyl alcohol in the blood, hemodialysis may be necessary. Hemodialysis acts as an artificial kidney to directly filter the alcohol and its metabolite, acetone, from the bloodstream, enhancing their elimination.