SSRI — Selective Serotonin Reuptake Inhibitors

SSRIs are the most widely prescribed class of antidepressants in the world and the first-line pharmacological treatment for depression and most anxiety disorders. They work by blocking serotonin reuptake at the synapse, increasing its availability in the central nervous system.

Commonly prescribed SSRIs include: fluoxetine (Prozac and generics — the oldest), sertraline (Zoloft and generics — the most widely used globally), escitalopram (Lexapro — well tolerated), paroxetine (Paxil — sedating, useful for anxiety with insomnia), and citalopram (Celexa and generics).

SSRIs take 2–4 weeks to reach their full antidepressant effect and 4–8 weeks for their full anti-anxiety effect. Common early side effects include nausea, headache, insomnia or drowsiness, and agitation — usually transient. The most persistent side effect is sexual dysfunction (affecting 30–40% of users). They are safe for long-term use and are not habit-forming (unlike benzodiazepines).

Whether a medication is classified as "controlled" varies by country; in most places SSRIs require only a standard prescription rather than special controlled-substance authorization. Dose adjustments and the choice of a specific SSRI are made together with a physician.