What are Selective Serotonin Reuptake Inhibitors (SSRIs)?

Selective serotonin reuptake inhibitors, or SSRIs, were the first antidepressants developed. These are now the most commonly prescribed antidepressants. They are prescribed to treat depression, but are also used to treat a wider range of depressive disorders, anxiety disorders, and post-traumatic stress disorder (PTSD).

Depression is common. Depression affects approximately 6.7% of the population (16.1 million people) of the United States each year, and these are only those who have been clinically diagnosed. Medications such as SSRIs, along with other depression treatment options like talk therapy, can make depression a very treatable condition.

This article explains how SSRIs work, under what conditions they are used, and the different types you may encounter on your own mental health journey. You will also learn about the most common side effects and important safety precautions.

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What are SSRIs?

True to their name, SSRIs are drugs that inhibit or limit serotonin reuptake. Serotonin is the chemical messenger associated with mood, energy, sexual functioning, digestion, and sleep. It is naturally present in the intestine, the brain and the central nervous system.

By inhibiting serotonin reuptake, SSRIs work to increase serotonin levels in your body. Low levels of serotonin are associated with depression.

Recent research also suggests that SSRIs work by altering the functioning of nerve cells in the brain.

How are SSRIs used?

SSRIs are approved by the Food and Drug Administration (FDA) to treat depression, anxiety, and other mood disorders.


SSRIs approved by the FDA to treat depression, anxiety, and other mood disorders include:

  • Celexa (citalopram)
  • Lexapro (escitalopram)
  • Luvox (fluvoxamine)
  • Paxil, Paxil CR, Pexeva (paroxetine)
  • Prozac (fluoxetine)
  • Trintellix (vortioxetine)
  • Vibrid (vilazodone)
  • Zoloft (sertraline)

Not all SSRIs are approved for treating all mood disorders.

Possible Side Effects of SSRIs

The FDA lists the following common side effects of SSRIs:

Seizures, abnormal bleeding or bruising, and withdrawal symptoms when adjusting medications can be more serious side effects of SSRIs.

Safety and Precautions

SSRIs may not be an option for everyone. Only you and your healthcare provider can decide which, if any, antidepressant is right for you.

Drugs interactions

If you are already taking other medications, SSRIs may interact with them, increasing the risk of side effects or overdose symptoms.

Negative drug interactions usually involve combinations of an SSRI with other psychotropics (psychoactive drugs that impair nervous system functions), especially tricyclic antidepressants and monoamine oxidase inhibitor (MAOI), lithium, clozapine and methadone. Drug interactions are common with SSRIs, especially with other psychotropics.

Herbal and natural products can also cause drug interactions with SSRIs. Examples include Japanese ginkgo biloba, which can cause hemorrhaging, and ginseng, which can cause serotonin syndrome.

Serotonin Syndrome

Serotonin syndrome is a life-threatening reaction to the presence of excessive amounts of serotonin in the nervous system. This can happen when taking SSRIs and other substances that impact serotonin called serotonergic drugs.

Pain relievers, some migraine medications, herbal supplements (like St. John’s Wort), and antidepressants like SSRIs fall into this category. That implies:

  • Mental status changes: This may include anxiety, agitation, disorientation (confusion) and excited delirium.
  • Autonomous instability: Unconscious changes in the functioning of the nervous system, which may include sweating, rapid heartbeat, elevated body temperature, high blood pressure, vomiting and diarrhea.
  • Neuromuscular hyperactivity: Changes in muscle activity and control, which may include tremors, involuntary muscle twitches and overactive reflexes.


SSRIs are generally considered safe during pregnancy. Untreated depression in pregnancy is not safe for the person or the growing fetus with specific neonatal needs.

Previously, there was a public health advisory for SSRIs during pregnancy due to the risk of persistent pulmonary hypertension of the newborn (PPHN), which is a low concentration of oxygen in the blood due to circulation problems . This advice has since been recalled because it was based on a single published study. More recent data show that PPHN is rare and doctors should not change their treatment for depression.

Children and teenagers

Antidepressants carry an FDA black box warning of an increased risk of suicidal thoughts and behaviors in some people under 25.

The benefits of SSRIs may outweigh the risks, but close supervision of children and adolescents taking antidepressants is necessary.

suicidal thoughts

There is a risk of suicidal thoughts associated with depression, mood disorders and the use of antidepressants, but this is not a direct relationship, nor explained simply. A 2021 study demonstrated that suicidal thoughts were more likely the month before starting antidepressants than the month after or the year after. The results do not confirm that SSRI treatment increases the risk of suicidal behavior, but it is possible that SSRI treatment reduces the risk.

When to stop treatment

Depression, like any mental health issue, is truly different for everyone. This means that there is no “standard” treatment for antidepressants. That said, health care providers generally recommend taking the drugs for six to nine months before deciding to stop them.

However, if you have had three or more recurrences of depression, your doctor may recommend that you continue treatment for two years after your symptoms have stopped or stabilized. Only you and your providers can determine when or if stopping treatment is best for you.

How to find the right antidepressant

The right antidepressant can take trial and error to find. This is because it is not possible to predict with certainty how your body chemistry will react to the drug.

If an SSRI doesn’t seem to work or the side effects are unmanageable, talk to your prescribing doctor about trying another antidepressant. This may include another SSRI or another class of drugs such as selective norepinephrine reuptake inhibitors (SNRIs).


SSRIs are the most commonly prescribed antidepressants. They are used to treat depression, anxiety and other mood disorders. There are also off-label uses. Some safety precautions exist, but this class of drugs is generally considered by providers to be a safe choice for treating depression.

A word from Verywell

Depression is a complex mental health condition with many potential causes and factors that can either promote recovery or work against treatment efforts. Although medication can be a vital tool for people with depression, it is not the only option, nor should it be considered the only tool for managing depression. You can also consider talking therapy, which can help you resolve any underlying issues (past or present).

Frequently Asked Questions

  • Which SSRIs are best for treating depression?

    Prozac (fluoxetine) is the best documented SSRI for treating depression, but which SSRI is right for you will depend on individual factors. Only you and your health care provider can determine which antidepressant may be most beneficial for your situation.

  • Are SSRIs only used to treat depression?

    SSRIs are used to treat a variety of conditions, including depressive disorders, anxiety disorders, and other mood disorders. Healthcare providers may also prescribe SSRIs for off-label uses, depending on the person’s medical history and medical condition.

  • Do selective serotonin reuptake inhibitors help with anxiety?

    Yes. SSRIs are used to treat anxiety. Serotonin impacts a range of moods and emotions, not just depression or happiness. Adequate levels of serotonin are associated with calm and happiness.

  • What does “inhibit serotonin reuptake” mean?

    the term “inhibit serotonin reuptake” means to prevent the reabsorption of serotonin in order to increase overall levels in your body.

  • Can you drink alcohol with SSRIs?

    It is not recommended to drink alcohol while taking antidepressants. You should not combine them. This could have side effects like impaired thinking and increased drowsiness.

  • What is the difference between SNRIs and SSRIs?

    The difference is that SSRIs only target serotonin, but SNRIs block or inhibit the reuptake of serotonin and another chemical messenger associated with mood called norepinephrine. It is used to treat other conditions besides depression, including fibromyalgia.

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