Tranquilizer drugs are also called depressants because of the way they work on the central nervous system. Your doctor may prescribe you tranquilizers or depressants if you suffer from anxiety and/or have difficulty sleeping. Tranquilizers may also be useful for preventing seizures or relaxing muscle spasms.
Doctors prescribe tranquilizers frequently. This makes them fairly easy for unauthorized users to access and divert for illicit purposes. According to the Drug Enforcement Agency, there are two categories of tranquilizers with accepted medical uses in the United States: barbiturates and benzodiazepines.
Barbiturates are an older type of tranquilizer drugs. The first medical use of barbiturates took place in the 1900s. Doctors used to prescribe them much more widely than they do today, and for more complaints. Eventually, however, doctors and researchers found that barbiturates could have significant adverse effects.
One of the most concerning side effects is tolerance. This occurs when your body gets used to the medication and you have to take higher doses to achieve the same effects. Barbiturates have largely fallen out of favor as medical treatments because of the negative side effects. However, today there are 12 that still have accepted medical uses and that doctors may prescribe.
Benzodiazepines are more recent than barbiturates. They exist due to efforts to develop medications that could treat the same conditions as barbiturates with fewer harmful side effects. This was successful to a certain extent, and it is now much more common for doctors to prescribe benzodiazepines than barbiturates.
However, benzodiazepines still have abuse potential. As with barbiturates, it is possible to build up a tolerance to benzodiazepines. Both barbiturates and benzodiazepines can cause coma and death if you were to overdose on either due to their effects on the central nervous system.