How Do Selective Serotonin Reuptake Inhibitors (SSRIs) Work?

Phuoc Anh (Anne) Nguyen, PharmD, MS, BCPS
·4 min read
1

Medically reviewed by David Snyder, PharmD, BCPP

Selective serotonin reuptake inhibitors (SSRIs) are a group of prescription medications prescribed to treat symptoms of depression, anxiety, and other mental health conditions. These medications can effectively reduce your symptoms with a unique process to achieve that goal.

While their mechanism of action (how they work) is not fully understood, SSRIs help reduce symptoms of depression by affecting certain neurotransmitters in the body.

This article will discuss how SSRIs work, how effective they are, and how long they take to work.

<p>Getty Images / Maca and Naca</p>

Getty Images / Maca and Naca

How SSRIs Work

SSRIs are a group of medications prescribed to treat anxiety and depression. SSRIs work by selectively increasing overall levels of serotonin in the body. They target the serotonin transporter (SERT) protein, which transports serotonin between neurons. In doing this, SSRIs block serotonin's reabsorption (reuptake) in the nerve cells so that more serotonin remains in the body.

Serotonin is a neurotransmitter that influences mood, happiness, learning, memory, sleep, and other physiological processes. A neurotransmitter is a substance that nerve cells (neurons) use to communicate with one another.

SSRIs' ability to cause a prolonged presence of serotonin in the brain's neurons can elevate mood and feelings of happiness, which helps treat symptoms of depression.

However, SSRIs' mechanism of action is still not fully understood. Researchers have suggested that there is likely more to SSRIs' therapeutic effects than their effects on serotonin.

How Effective Are SSRIs?

According to a study that evaluates clinical trials on medications for depression, all SSRIs are effective at treating symptoms of depression compared to placebo.

In head-to-head trials, certain SSRIs, such as Lexapro (escitalopram) and Paxil (paroxetine), were more effective than other SSRIs, such as Luvox (fluvoxamine) and Prozac (fluoxetine).

Additionally, some SSRIs come with fewer side effects than others. Studies have shown that some SSRIs, such as Celexa (citalopram), Lexapro, and Prozac, were more tolerable than other antidepressants with SSRI activity, like Cymbalta (duloxetine, an SNRI) and Luvox (another SSRI).

However, although SSRIs' efficacy and side effects vary, the overall goal of reducing major depression is met.

Some SSRIs also worked better in a particular age group. For example, studies have shown that Prozac tends to be more effective in children and adolescents than other antidepressants.

Overall, not everyone will respond the same to each SSRI. Therefore, what works best for you may depend on several factors, including how much your symptoms improve and how well you tolerate the medication.

Related: Comparing Prozac vs. Lexapro

How Long Do SSRIs Take to Work?

SSRIs usually will not work right away. You may start to see an effect with SSRIs within four to six weeks.

Continue taking your medication as prescribed without abruptly stopping to reach a full effect. If no response is shown after that period, consider talking to your healthcare provider to determine an alternative option.

What Are Common SSRIs?

Examples of commonly prescribed SSRIs include:

  • Celexa (citalopram)

  • Lexapro (escitalopram)

  • Prozac (fluoxetine)

  • Luvox (fluvoxamine)

  • Paxil, Paxil CR (paroxetine)

  • Zoloft (sertraline)

Summary

SSRIs are a group of antidepressants used to treat mental health conditions, such as major depressive disorder, generalized anxiety disorder, obsessive compulsive disorder (OCD), and more.

They work by inhibiting the reuptake of serotonin, which extends the amount of serotonin's activity in the brain. However, although it's not fully understood yet, researchers suggest that SSRIs do more to help with depression symptoms.

SSRIs are usually the first-line medicine for depression because they tend to cause fewer side effects compared to other medications. However, everyone's response to antidepressants is different. It might take some trial and error to find the treatment plan that works best for you.

Frequently Asked Questions

What conditions do SSRIs treat?

SSRIs have been approved to treat a variety of mental health conditions. SSRIs are known to treat major depressive disorder. These medications can also treat generalized anxiety disorder, obsessive-compulsive disorder, and bulimia nervosa.

What should I do if I don’t notice any symptom improvement?

You may notice improvement with SSRIs within four to six weeks. It is important to continue taking your medication as prescribed. If you don't notice any improvements, contact your healthcare provider before making any changes.

The author would like to recognize and thank Ghassan Alyaseen for contributing to this article.