Blackouts, sometimes referred to as alcohol-related memory loss or "alcoholic amnesia," occur when people have no memory of what happened while intoxicated. These periods may last from a few hours to several days. During a blackout, someone may appear to be fine; however, once sober, he/she has no recollection of events.
Passing out happens when someone loses consciousness from drinking excessive amounts of alcohol. Losing consciousness means that the person has reached a very dangerous level of intoxication; furthermore, he/she could slip into a coma and die. If someone has passed out, seek immediate medical attention.