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Selective serotonin reuptake inhibitors (SSRIs)

SSRIs, a popular antidepressant type, can help you overcome depression. Discover how Prozac and other SSRIs boost mood and what side effects they may cause.

By Mayo Clinic staff

SSRIs (selective serotonin reuptake inhibitors) are the most commonly prescribed antidepressants. They can ease symptoms of moderate to severe depression, are relatively safe and generally cause fewer side effects than other types of antidepressants.

How selective serotonin reuptake inhibitors work

SSRIs ease depression by affecting chemical messengers (neurotransmitters) used to communicate between brain cells. Most antidepressants work by changing the levels of one or more of these naturally occurring brain chemicals.

SSRIs block the reabsorption (reuptake) of the neurotransmitter serotonin (ser-oh-TOE-nin) in the brain. Changing the balance of serotonin seems to help brain cells send and receive chemical messages, which in turn boosts mood. SSRIs are called selective because they seem to primarily affect serotonin, not other neurotransmitters.

Selective serotonin reuptake inhibitors approved to treat depression

SSRIs approved by the Food and Drug Administration to treat depression, with their generic names followed by brand names in parentheses, include:

  • Citalopram (Celexa)
  • Escitalopram (Lexapro)
  • Fluoxetine (Prozac, Prozac Weekly, Sarafem)
  • Paroxetine (Paxil, Paxil CR, Pexeva)
  • Sertraline (Zoloft)
  • Fluoxetine combined with the atypical antipsychotic olanzapine (Symbyax)

Some SSRIs are available in extended-release form or controlled-release form, often designated with the letters XR or CR. These SSRIs provide controlled release of the medication throughout the day or for a week at a time with a single dose.

These medications may also be used to treat conditions other than depression.

Side effects of selective serotonin reuptake inhibitors

All SSRIs work in a similar way and generally cause similar side effects. However, each SSRI has a different chemical makeup, so one may affect you a little differently from another.

Side effects of SSRIs can include:

  • Nausea
  • Dry mouth
  • Headache
  • Diarrhea
  • Nervousness, agitation or restlessness
  • Reduced sexual desire or difficulty reaching orgasm
  • Inability to maintain an erection (erectile dysfunction)
  • Rash
  • Increased sweating
  • Weight gain
  • Drowsiness
  • Insomnia

You may experience less nausea with extended- and controlled-release forms of SSRIs. As with most antidepressants, sexual side effects are common with SSRIs. They occur in over half the people who take them.

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References
  1. Schatzberg AF, et al. Antidepressants: Introduction. In: Schatzberg AF, et al. Manual of Clinical Psychopharmacology. 7th ed. Arlington, Va.: American Psychiatric Publishing; 2010. http://www.psychiatryonline.com/content.aspx?aID=600624. Accessed Oct. 5, 2010.
  2. Fava M, et al. Antidepressants. In: Stern TA, et al. Massachusetts General Hospital Comprehensive Clinical Psychiatry. Philadelphia, Pa.: Mosby; 2008. http://www.mdconsult.com/das/book/body/221513496-3/0/1657/421.html?tocnode=57543329&fromURL=421.html#4-u1.0-B978-0-323-04743-2..50045-7_1104. Accessed Oct. 5, 2010.
  3. Chew RH, et al. Selective serotonin reuptake inhibitors and mixed-action antidepressants. In: Chew RH, et al. What your patients need to know about psychiatric medications. 2nd ed. Washington, DC.: American Psychiatric Publishing; 2009.
  4. Bostwick JM. A generalist's guide to treating patients with depression with an emphasis on using side effects to tailor antidepressant therapy. Mayo Clinic Proceedings. 2010;85:538.
MH00066 Dec. 9, 2010

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