Which medication is commonly used for the treatment of anxiety and is not an SSRI?

Diazepam is commonly used for the treatment of anxiety and is classified as a benzodiazepine, rather than a selective serotonin reuptake inhibitor (SSRI). Benzodiazepines like diazepam work by enhancing the effect of the neurotransmitter gamma-aminobutyric acid (GABA) in the brain, leading to a calming effect, which is why they are often used as anxiolytics.

In contrast, the other options listed—sertraline, fluoxetine, and paroxetine—are all SSRIs that primarily treat depression and also have efficacy in treating anxiety disorders by increasing serotonin levels in the brain. These differences in classification and mechanism of action highlight why diazepam is the correct choice for this particular question about anxiety treatment medication that does not belong to the SSRI category.