Benzodiazepines are a class of medicines that enhance the effect of GABA, the brain's main calming neurotransmitter. Examples include alprazolam, lorazepam, clonazepam, and diazepam. They are controlled substances in the United States.
Their labeling carries boxed warnings about risks when combined with opioids and about abuse, misuse, addiction, physical dependence, and withdrawal reactions. Hydroxyzine is not a benzodiazepine and is not a controlled substance, which is one of the reasons the two are frequently compared.