However, even small doses taken for a few days can cause withdrawal symptoms when use of barbiturates is stopped. Over 3 million Americans use and abuse barbiturates every year without medical supervision. About 5,000 deaths and tens of thousands of emergency room visits result each year from barbiturate overdoses, many occurring because they were taken with alcohol. However, the amount needed to cause death remains the same. As a result, there is a decreasing margin for safety between an effective dose and a deadly one.
Death also can occur when barbiturates are combined with other drugs, especially alcohol.
Barbiturates are classified according to how long their effects last. There also is a classification for ultra-short acting barbiturates, which are usually taken intravenously and may cause sedation before the injection is completed. It is this mental state that makes these barbiturates attractive to regular users. Long-acting barbiturates are seldom abused because it takes too long for their effects to be felt. In the short term, barbiturates are similar to alcohol, causing a lessening of tension.