Selective serotonin reuptake inhibitors (SSRIs) are a type of antidepressant medication. SSRIs are the most commonly prescribed antidepressants because they generally have few side effects.

How SSRIs Work

Serotonin is one of many brain chemicals that transmit messages between brain cells. The body produces serotonin by converting the amino acid tryptophan. Serotonin has been called the “feel-good chemical” because it induces a relaxed state of wellbeing. SSRIs inhibit the absorption of serotonin into the bloodstream, which keeps a higher level of serotonin circulating in the brain.

Because depression is associated with low levels of certain brain chemicals (including serotonin, dopamine, and norepinephrine), SSRIs can relieve depression by increasing the amount of available serotonin in the brain. SSRIs don’t cause the body to make more serotonin. They simply help the body use what it has more effectively.

Who Should Take SSRIs

SSRIs are often tried as first-line antidepressants because they typically have fewer side effects than other antidepressants. SSRIs are generally safe but should be used with caution by children and pregnant women. In 2004, the FDA added a black-box warning to SSRIs to note an increased risk of suicidal thoughts and behavior in children who use them. Further studies suggest that the benefits of antidepressant medication may outweigh the risk of suicidal thoughts. Children and adolescents taking SSRIs should be closely monitored for worsening depression or suicidal thoughts, especially during the first four weeks of treatment.

SSRIs may increase the risk of certain birth defects, especially heart and lung problems. Doctors and moms-to-be must weigh the risk of treatment with antidepressants versus the risk of untreated depression, which can also lead to poor pregnancy outcomes. Some pregnant women are able to switch SSRIs to minimize risk while adequately treating depression. Paroxetine (Paxil), for instance, is associated with fetal heart defects, breathing difficulty in the newborn, and brain disorders. Fluoxetine (Prozac) or citalopram (Celexa) might be other options during pregnancy.

Possible Side Effects

Side effects may vary from medication to medication. If you experience unpleasant side effects, talk to your healthcare provider. Switching to a different medication—even another SSRI—might help.

Possible side effects include:

  • nausea
  • dry mouth
  • headache
  • insomnia
  • tiredness
  • sexual dysfunction (inability to maintain an erection or orgasm)
  • diarrhea
  • weight gain
  • increased sweating
  • rash
  • nervousness

Brand Names

There are a number of SSRIs on the market. The generic names are listed below with their brand-name counterparts in parentheses.

  • citalopram (Celexa)
  • escitalopram (Lexapro)
  • fluoxetine (Prozac, Sarafem)
  • fluvoxamine (Luvox)
  • paroxetine (Paxil, Paxil XR, Pexeva)
  • sertraline (Zoloft)

What the Expert Says

“Selective serotonin reuptake inhibitors are very safe drugs, generally speaking,” says Danny Carlat, MD, Associate Clinical Professor of Psychiatry at Tufts University School of Medicine. “While there are some pretty minor side effects, it would be very hard for anyone to do any damage to themselves by taking an SSRI.”

Carlat adds that all SSRIs are fairly similar in terms of effectiveness. They do differ a little bit in some aspects, such as side effects and interactions with other drugs. People who can’t tolerate the side effects of one SSRI are often prescribed another.