About Sertraline Selective Serotonin Reuptake Inhibitor (SSRI), Antidepressant, Antidepressant Mechanism of Action of Sertraline Sertraline blocks the re-uptake of neurotransmitter Serotonin from the synapse in to the presynaptic nerve terminal in the CNS. This will prolong the action of Serotonin (5HT) and it is useful in the treatment of depression. Side Effects of Sertraline 1. Insomnia 2. Nausea 3. Diarrhoea 4. Headache 5. Fatigue 6. Dizziness 7. Tremor 8. Somnolence 9. Dry mouth 10. Anorexia 11. Impotence 12. Increased sweating 13. Constipation 14. Dyspepsia 15. Agitation 16. Malaise 17. Abdominal pain