Benzodiazepines (BZs) are the newest class of widely prescribed psychoactive chemicals that relieve anxiety. Diazepam, or Valium, is the most commonly abused BZ because it is the fastest acting. Alpraolam, or Xanax, is also a commonly abused BZ because of its quick onset. Differences in BZs typically vary in the rate they are absorbed, metabolized, and excreted. Some are used as sleeping pills because they induce drowsiness; examples of these BZs are lorazepan (Activan), triazolam (Halcion), and flurazepam (Dalmane).

Physical and mental effects include: sedation (tolerance is acquired quickly with sedatives), short-term memory impaiment, physical dependence under long-term use, withdrawal symptoms that include anxiety, sweating, and restlessness, dysphoria, hypersensitivity to stimuli, seizures and toxic psychoses under sudden withdrawal, and other uncomfortable and persistent symptoms that make it difficult for people to discontinue use. One difficult factor to determine is whether the cessation of use causes a re-emergence of the anxiety illness or is merely withdrawal symptoms. It is also important to differentiate between a person being physically addicted, which will be accompanied by psychological dependence and other chemical addictions (it is commonly reported that individuals who abuse BZs also abuse other substances as well), and a person merely experiencing withdrawal symptoms.