SSRIs, or selective serotonin reuptake inhibitors, are the most commonly prescribed antidepressants and a first-line treatment for depression, generalized anxiety, panic disorder, social anxiety, OCD, PTSD and PMDD. The class includes fluoxetine (Prozac), sertraline (Zoloft), escitalopram (Lexapro), citalopram (Celexa), paroxetine (Paxil) and fluvoxamine (Luvox). They work by blocking the transporter that pulls serotonin back into the nerve cell that released it, which leaves more serotonin available in the gap between neurons. Over weeks, that change leads to downstream adaptations in receptor sensitivity and gene expression that are thought to produce the clinical benefit.
SSRIs usually take two to four weeks to begin helping and six to eight weeks to show their full effect at a given dose. Common early side effects include nausea, headache, jitteriness and sleep changes, which often fade within two weeks. Sexual side effects and weight change can persist and are worth discussing openly, since switching within the class or to another class often solves them. SSRIs are not habit-forming, but stopping suddenly can cause discontinuation symptoms such as dizziness and flu-like feelings, so they are tapered. About one third of people reach full remission on the first SSRI they try, and many more respond partially. When that happens, your provider may raise the dose, switch, or add an augmentation strategy. SSRIs are also the oral antidepressant most often paired with Spravato.