The immediate physical effects of drinking alcohol range from mild mood changes to complete loss of coordination, vision, balance, and speech -- any of which can be signals of acute alcohol intoxication, or drunkenness. These effects usually wear off in a matter of hours after a person stops drinking. Many law-enforcement agencies regard a .08 percentage of alcohol in the bloodstream as evidence of intoxication. Larger amounts of blood alcohol can impair brain function and eventually cause unconsciousness.