Alcohol poisoning shuts down the body’s most basic automatic functions. At dangerously high blood alcohol levels, typically above 0.30%, alcohol suppresses the parts of the brain that control breathing, heart rate, temperature regulation, and the gag reflex. In the United States, alcohol-related poisoning caused an average of 21,806 deaths per year during 2020–2021, a sharp increase from about 14,944 annual deaths just a few years earlier.
How Alcohol Suppresses the Brain
Alcohol is a central nervous system depressant, meaning it slows the rate at which the brain and spinal cord can send and receive signals. At low doses, this produces the familiar effects of relaxation and lowered inhibitions. At toxic levels, the suppression becomes dangerous because it extends beyond mood and coordination to the brain regions that keep you alive without conscious effort.
The progression is predictable. At a blood alcohol concentration (BAC) around 0.10% to 0.15%, a person has trouble walking and keeping balance. By 0.15% to 0.25%, they become extremely drowsy and may not be able to sit upright. At 0.30%, a person with no tolerance to alcohol can slip into a coma. Above 0.40%, respiratory arrest and death become likely. These thresholds can vary based on body size, tolerance, and how quickly the alcohol was consumed, but the general pattern holds: alcohol moves from impairing judgment to impairing consciousness to shutting down involuntary body functions.
One of the chemical messengers most affected is the one responsible for forming new memories, which is why blackouts happen well before someone reaches life-threatening levels. But alcohol also disrupts signaling pathways involved in mood, pain perception, muscle control, and arousal. At overdose levels, these disruptions compound until the brain can no longer maintain the baseline operations it normally handles without any conscious input.
Breathing and the Gag Reflex
The most immediately deadly effect of alcohol poisoning is what it does to breathing. Alcohol suppresses the brainstem’s respiratory center, causing breaths to become slow, shallow, and irregular. In severe cases, breathing stops entirely.
At the same time, alcohol suppresses the gag reflex. This creates a specific and common cause of death: a person who is unconscious from alcohol vomits, and because their gag reflex no longer works, they inhale the vomit into their lungs instead of coughing it out. This can block the airway completely or cause a severe and sometimes fatal lung injury. Even people who survive this kind of event can suffer lasting brain damage from the period of oxygen deprivation.
This is why the common advice to “let them sleep it off” can be fatal. Someone who has passed out from drinking may still have rising alcohol levels in their blood as their stomach continues absorbing what they already drank. Their breathing can slow or stop while they appear to be sleeping.
Heart and Blood Pressure Changes
Toxic levels of alcohol force the heart to work abnormally. Heart rate can spike above 100 beats per minute, a condition called tachycardia, and the heart’s rhythm can become irregular. Binge drinking, defined as four or more drinks within two hours for women and five or more for men, can trigger a sudden irregular heartbeat even in people who don’t normally drink. This phenomenon, sometimes called holiday heart syndrome, raises the risk of stroke, heart attack, and heart failure.
Blood pressure also rises temporarily during heavy drinking. Combined with an erratic heart rhythm and depressed breathing, these cardiovascular effects put enormous stress on a body that is simultaneously losing its ability to regulate itself.
Blood Sugar and Body Temperature Drops
Alcohol interferes with the liver’s ability to release stored sugar into the bloodstream. During alcohol poisoning, blood sugar can plummet to dangerously low levels. The brain depends on a constant supply of glucose to function, so severe low blood sugar on top of alcohol’s direct brain suppression compounds the risk of seizures, loss of consciousness, and brain damage.
Body temperature also drops. Alcohol dilates blood vessels near the skin’s surface, which creates a feeling of warmth while actually accelerating heat loss. A person with alcohol poisoning who is outdoors or in a cold environment can develop hypothermia quickly, and their impaired brain may not register the cold or prompt them to seek shelter. Young children are especially vulnerable to both of these effects. Infants and toddlers can develop profound low blood sugar, hypothermia, and coma after ingesting amounts of alcohol that would barely affect an adult.
Lasting Damage After Survival
Surviving alcohol poisoning does not always mean a full recovery. The period of oxygen deprivation that occurs during slowed or stopped breathing, choking on vomit, or prolonged seizures can cause permanent brain damage. The severity depends on how long the brain went without adequate oxygen, but even relatively brief interruptions can destroy brain cells that do not regenerate.
The NIAAA states plainly that alcohol overdose can lead to permanent brain damage or death. Cognitive problems, memory impairment, and difficulty with coordination can persist long after the acute event. Some people experience kidney damage from the combination of dehydration, low blood pressure, and the toxic burden on the body’s filtration systems.
What Happens at the Emergency Room
Emergency treatment for alcohol poisoning focuses on keeping a person alive while their body processes the alcohol. The first priority is protecting the airway, since choking on vomit is the most immediate threat. If someone cannot maintain their own breathing, a tube may be placed to keep the airway open and deliver oxygen.
Fluids are given intravenously to combat dehydration and help stabilize blood sugar and electrolyte levels. In the vast majority of cases, the treatment is supportive: monitoring vital signs, preventing choking, and waiting for the body to metabolize the alcohol. The liver clears alcohol at a relatively fixed rate, and there is no way to speed that up significantly. In rare and extreme cases with blood alcohol levels above 450 mg/dL, or when someone has ingested toxic types of alcohol like methanol, more aggressive interventions like dialysis may be considered.
Recovery time varies. Someone treated for moderate alcohol poisoning may feel severely ill for 24 to 48 hours. Those who experienced oxygen deprivation, seizures, or organ stress face a longer and less predictable recovery, with the possibility that some effects will be permanent.
Why Children Face Greater Risk
Children, especially infants and toddlers, are far more vulnerable to alcohol poisoning than adults. Their smaller body size means even a small amount of alcohol can produce a dangerous blood alcohol level. Young children are also more prone to severe drops in blood sugar and body temperature, both of which can become life-threatening faster than in adults. Neurological warning signs like confusion, drowsiness, and loss of coordination are harder to recognize in young children, which can delay treatment. Products like hand sanitizer, mouthwash, and cooking extracts contain enough alcohol to poison a small child, making accidental ingestion a real concern in households with young kids.