“Downers” like Xanax, Valium and Klonopin make users feel calm and relaxed by increasing the brain’s nerve-calming agent, called GABA. It’s hard to get off this drug once a tolerance starts to build up, which can take place very quickly. More than 15 types of benzodiazepines, aka “benzos,” are available via prescription, although forms of the substance are traded on the black market as well.

Benzodiazepines are considered a minor tranquilizer, and they affect the user in the short term with side effects such as impaired cognition, lethargy, depression, altered vision, impaired motor function, tremors, nausea and abdominal pain. Long-term use of benzos can cause brain damage, and withdrawal symptoms include body aches, muscle stiffness, sleep disturbance, anxiety, seizures, irritability and memory problems. There were approximately 8,000 deaths because of benzodiazepine overdose in the U.S. in 2014, according to the National Institute on Drug Abuse.