Experiencing blackouts is a warning sign that alcoholism is probable. At least this is the consensus among most addiction treatment specialists today. A single episode of heavy drinking can cause a blackout, and not indicate a problem with alcohol, but when blackout episodes are repeated, there is a good chance that alcohol is a problem. Speaking from experience, as I was an alcoholic drinker for many years, blackouts are a scary thing. Nothing is worse than waking up the next morning and not only having a hellacious hangover, but not remembering quite what you did the night before.