SRIs

Serotonin reuptake inhibitors (SRIs) are a class of drugs that inhibit the reuptake of serotonin (5-HT) into presynaptic neurons, primarily by blocking the serotonin transporter (SERT). By increasing serotonin levels in the synaptic cleft, SRIs enhance serotonergic neurotransmission. The best known SRIs are the selective serotonin reuptake inhibitors (SSRIs), a widely used subset recognized for their generally favorable safety and tolerability profiles.

Common SRIs include fluoxetine, sertraline, citalopram, escitalopram, paroxetine, and fluvoxamine. While SSRIs are the most familiar members, SRIs as a category emphasize the shared mechanism of serotonin reuptake inhibition rather than a single pharmacologic profile.

SRIs are used in the treatment of major depressive disorder and various anxiety disorders, including generalized anxiety disorder, panic disorder, social anxiety disorder, and obsessive-compulsive disorder. They are also prescribed for post-traumatic stress disorder, premenstrual dysphoric disorder, and some chronic pain conditions. Onset of therapeutic effects typically takes several weeks, with full benefits often appearing after several weeks of treatment.

Common side effects can include nausea, insomnia or sedation, sexual dysfunction, headaches, dry mouth, and sweating. Weight changes may occur in some patients. Because SRIs influence serotonin levels, there is a risk of serotonin syndrome when combined with other serotonergic drugs. Discontinuation should be gradual to minimize withdrawal symptoms such as flu-like symptoms, anxiety, irritability, and sleep disturbances. When considering SRIs in pregnancy or with other medications, clinical guidance should be consulted to balance risks and benefits.