The latest research, learnings, and insight on mental health.

Selective Serotonin Reuptake Inhibitors (SSRIs): Mechanism, Benefits, & Disadvantages

If you go to your doctor with symptoms of depression or anxiety, chances are they will start prescribing you an SSRI. But what exactly are SSRIs, and what side effects do they have?

A brief explanation about SSRIs

Selective Serotonin Reuptake Inhibitors (SSRIs) are a widely used class of antidepressants, frequently prescribed to treat depression, anxiety disorders, and various other mental health conditions.

SSRIs work by increasing the levels of serotonin, a neurotransmitter that helps regulate mood and anxiety, in the brain. Serotonin is released by nerve cells and travels to other nerve cells to deliver signals. After the signal is delivered, the excess serotonin is reabsorbed by the initial nerve cell in a process called reuptake. SSRIs block this reuptake process, leaving more serotonin available in the space between nerve cells, which can help alleviate symptoms of depression and anxiety.1

Benefits of SSRIs

SSRIs have demonstrated efficacy in treating a wide range of mental health disorders, including major depressive disorder (MDD), generalized anxiety disorder (GAD), panic disorder, obsessive-compulsive disorder (OCD), and post-traumatic stress disorder (PTSD).2 In a meta-analysis of 522 clinical trials involving SSRIs, all found that they are more effective than placebo in treating MDD and GAD.3

Compared to older classes of antidepressants, such as tricyclic antidepressants (TCAs) and monoamine oxidase inhibitors (MAOIs), SSRIs generally are safer and have fewer side effects. [4] The side effects associated with SSRIs are often mild and transient, and they are less likely to cause serious or life-threatening complications, such as cardiotoxicity (heart toxicity) and fatal overdose, which can occur with TCAs and MAOIs.1

Disadvantages of SSRIs

SSRIs have tons of side effects!

Despite their overall favorable safety profile, SSRIs can cause side effects, which may include nausea, diarrhea, headache, insomnia, drowsiness, sexual dysfunction, and weight gain.4 These side effects can be distressing for patients and may lead to discontinuation of treatment in some cases.

Some of the most common SSRI side effects include:

  • Nausea and vomiting
  • Diarrhea or constipation
  • Drowsiness or insomnia
  • Headache
  • Sexual dysfunction, such as decreased libido or difficulty achieving orgasm
  • Weight gain or loss
  • Dry mouth
  • Sweating

It's important to note that not everyone will experience these side effects, and some may be more severe than others. Additionally, side effects may vary depending on the specific SSRI being taken.

If you are experiencing side effects from SSRIs, it's important to talk to your healthcare provider. In some cases, they may recommend switching to a different medication or adjusting the dosage.

SSRIs take a while to start working

SSRIs may take several weeks to exert their full therapeutic effect, which can be frustrating for patients and clinicians.1 This delay in the onset of action may contribute to the risk of suicide or worse mood in some individuals, particularly during the initial stages of treatment.

Not a silver bullet

Although SSRIs are effective for many patients, a significant proportion of individuals may not respond adequately to treatment or may experience only partial symptom relief.5 Additionally, some patients may relapse after an initial response or may not achieve full remission of symptoms, necessitating the exploration of alternative treatments or adjunctive therapies.6


SSRIs have revolutionized the treatment of depression and anxiety disorders by offering a safer and more tolerable alternative to older classes of antidepressants. While they have shown efficacy in managing a variety of mental health conditions, there are disadvantages, including side effects and variable response rates. Further research is needed to optimize the use of SSRIs and develop novel treatments to address the unmet needs of patients with mental health disorders.

_ _ _


  1. Stahl, S.M. (2013) Stahl’s Essential Psychopharmacology Neuroscientific Basis and Practical Applications. 4th Edition, Cambridge University Press, Cambridge. - References - Scientific Research Publishing. (n.d.-c). https://scirp.org/reference/ReferencesPapers.aspx?ReferenceID=2100251
  2. Baldwin, D. S., Anderson, I., Nutt, D. J., Allgulander, C., Bandelow, B., Boer, J. a. D., Christmas, D. M., Davies, S. J., Fineberg, N. A., Lidbetter, N., Malizia, A., McCrone, P., Nabarro, D., O’Neill, C. A., Scott, J., Van Der Wee, N. J., & Wittchen, H. (2014). Evidence-based pharmacological treatment of anxiety disorders, post-traumatic stress disorder and obsessive-compulsive disorder: A revision of the 2005 guidelines from the British Association for Psychopharmacology. Journal of Psychopharmacology, 28(5), 403–439. https://doi.org/10.1177/0269881114525674
  3. Cipriani, A., Furukawa, T. A., Salanti, G., Chaimani, A., Atkinson, L. Z., Ogawa, Y., Leucht, S., Ruhé, H. G., Turner, E. H., Higgins, J. P. T., Egger, M., Takeshima, N., Hayasaka, Y., Imai, H., Shinohara, K., Tajika, A., Ioannidis, J. P. A., & Geddes, J. R. (2018). Comparative Efficacy and Acceptability of 21 Antidepressant Drugs for the Acute Treatment of Adults With Major Depressive Disorder: A Systematic Review and Network Meta-Analysis. Focus, 16(4), 420–429. https://doi.org/10.1176/appi.focus.16407
  4. Ferguson, J. J. (2001). SSRI Antidepressant Medications. Primary Care Companion to the Journal of Clinical Psychiatry, 03(01), 22–27. https://doi.org/10.4088/pcc.v03n0105
  5. Trivedi, M. H., Rush, A. J., Wisniewski, S. R., Nierenberg, A. A., Warden, D., Ritz, L., Norquist, G., Howland, R. H., Lebowitz, B. D., McGrath, P. J., Shores-Wilson, K., Biggs, M. M., Balasubramani, G. K., & Fava, M. (2006). Evaluation of Outcomes With Citalopram for Depression Using Measurement-Based Care in STAR*D: Implications for Clinical Practice. American Journal of Psychiatry, 163(1), 28–40. https://doi.org/10.1176/appi.ajp.163.1.28
  6. Rush, A. J., Trivedi, M. H., Wisniewski, S. R., Nierenberg, A. A., Stewart, J. P., Warden, M. D., Niederehe, G., Thase, M. E., Lavori, P. W., Lebowitz, B. D., McGrath, P. J., Rosenbaum, J. F., Sackeim, H. A., Kupfer, D. J., Luther, J. F., & Fava, M. (2006). Acute and Longer-Term Outcomes in Depressed Outpatients Requiring One or Several Treatment Steps: A STAR*D Report. American Journal of Psychiatry, 163(11), 1905–1917. https://doi.org/10.1176/ajp.2006.163.11.1905

Cover photo by Ksenia Yakovleva on Unsplash


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