Although many people enjoy moderate drinking, defined as 1 drink per day for women or 2 for men, drinking too much can lead to an overdose. Overdoses can range in severity, from problems with balance and slurred speech to coma or even death.

Underage drinkers may be at particular risk for alcohol overdose. Research shows that people under age 20 typically drink about 5 drinks at one time.1 Drinking such a large quantity of alcohol can overwhelm the body’s ability to break down and clear alcohol from the bloodstream. This leads to rapid increases in BAC and significantly impairs brain function. When BACs go even higher, amnesia (or blackouts) can occur.

Continuing to drink despite clear signs of significant impairments can result in a potentially deadly type of overdose called alcohol poisoning.

Alcohol poisoning occurs when there is so much alcohol in the bloodstream that areas of the brain controlling basic life-support functions—such as breathing, heart rate, and temperature control—begin to shut down.

Symptoms of alcohol poisoning include confusion; difficulty remaining conscious; vomiting; seizures; trouble with breathing; slow heart rate; clammy skin; dulled responses, such as no gag reflex (which prevents choking); and extremely low body temperature.

It is dangerous to assume that an unconscious person will be fine by sleeping it off. Alcohol acts as a depressant, hindering signals in the brain that control automatic responses such as the gag reflex. Alcohol also can irritate the stomach, causing vomiting. With no gag reflex, a person who drinks to the point of passing out is in danger of choking on vomit, which, in turn, could lead to death by asphyxiation. Even if the drinker survives, an alcohol overdose can lead to long-lasting brain damage.

(Source: http://pubs.niaaa.nih.gov)