Selective serotonin reuptake inhibitor (SSRI): overview, uses, and effects

How they work

SSRIs block the reabsorption (reuptake) of the neurotransmitter serotonin into presynaptic nerve cells, increasing its availability in the synaptic cleft. This change in serotonin signaling is thought to help regulate mood, anxiety, and other emotional processes. The biochemical action is more selective for serotonin than earlier antidepressants, which targeted multiple neurotransmitters.

Common uses

Clinically, SSRIs treat major depressive disorder and a range of anxiety-related conditions, including generalized anxiety disorder, panic disorder, obsessive–compulsive disorder and social anxiety. They are also used off-label for some chronic pain syndromes and other conditions. For treatment contexts, see resources about depression and anxiety disorders.

Examples

• Fluoxetine (widely known by brand names such as Prozac)
• Paroxetine (for example Paxil)
• Citalopram (sold as Celexa in some regions)
• Escitalopram (a related compound, marketed as Lexapro)

In many countries SSRIs are prescribed more often than older antidepressants; see comparative prescribing data at sources on prescribing patterns.

Effects, safety and distinctions

SSRIs commonly cause nausea, headache, sleep changes, and sexual side effects; some people experience weight change or emotional blunting. They are generally better tolerated than tricyclic antidepressants (TCAs) and monoamine oxidase inhibitors (MAOIs), which have different side-effect profiles and dietary restrictions. Serious but rare risks include serotonin syndrome (typically when combined with other serotonergic drugs) and a possible increase in suicidal thoughts for some young people; careful monitoring is advised, especially when starting or changing doses.

History and practical considerations

Introduced in clinical practice in the late 20th century, SSRIs shifted antidepressant therapy toward agents with greater tolerability and safety in overdose. They usually take several weeks to show full effect and should not be stopped abruptly because of possible discontinuation symptoms. Decisions about choice, dosing and duration are individualized, often following clinical guidelines and discussion between patient and clinician. For further clinical guidance consult authoritative resources such as drug class summaries or specialist literature (depression resources).