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Selective Serotonin Reuptake Inhibitors (SSRIs)

Reviewed by: HU Medical Review Board | Last reviewed: September 2023

Selective serotonin reuptake inhibitors (SSRIs) are usually the first type of drug used to treat major depressive disorder (MDD), often called simply depression. Many SSRIs can be used by kids and adults. Some are even safe for pregnant people.1-3

SSRIs also are used to treat other mental health conditions. These conditions include:2-4

  • Generalized anxiety disorder
  • Bipolar disorder
  • Obsessive-compulsive disorder (OCD)
  • Social anxiety disorder
  • Post-traumatic stress disorder (PTSD)
  • Premenstrual dysphoric disorder (PMDD)

How do SSRIs work?

The brain uses chemicals to send signals to the rest of the body. These chemicals are called neurotransmitters. Neurotransmitters play a role in mood, movement, behaviors, and more. Experts think 1 of the underlying causes of depression is an imbalance in certain neurotransmitters. Examples of neurotransmitters that may play a role in depression symptoms are serotonin, dopamine, and norepinephrine.5,6

People with depression may have lower levels of serotonin than those without depression. SSRI drugs target a receptor that affects serotonin balance. SSRIs prevent the reuptake and recycling of serotonin. This increases the amount of active serotonin in the brain. That increased serotonin activity is thought to help improve mood.2-4,7

SSRIs specifically affect serotonin, with little impact on other neurotransmitters. This helps reduce potential side effects of treatment compared to other common depression drugs that affect more than 1 neurotransmitter.1-3,5

Each person responds differently to SSRIs. It can take several weeks to notice an effect on symptoms. Some people may not be able to tolerate side effects or will not have much improvement. Your doctor may spend several weeks adjusting the dose of a new SSRI in slow amounts. This can help you tolerate the drug and build up to a dose that gives you relief.1,2

If you do not have a response to treatment in about 4 to 6 weeks, your doctor may recommend trying a different antidepressant drug. You may respond better to another SSRI or a different type of drug.1

Examples of SSRIs

There are several SSRI drugs available in the United States. Examples of these include:2,4,8

  • Escitalopram (Lexapro®)
  • Fluoxetine (Prozac®)
  • Sertraline (Zoloft®)
  • Citalopram (Celexa®)
  • Paroxetine (Paxil®)

Your doctor will choose an SSRI for you based on a few factors. They will consider your past treatment history, the other drugs you are taking, and your family history.1,2

What are the possible side effects of SSRIs?

Side effects can vary based on the specific drug you are taking. Common side effects of SSRI drugs include:2-4,8

  • Headache
  • Trouble sleeping (insomnia)
  • Nausea or vomiting
  • Diarrhea
  • Nervousness or restlessness
  • Dry mouth
  • Sleepiness
  • Changes in appetite (leading to weight gain or loss)
  • Problems with sexual function like reduced sexual desire, trouble maintaining an erection (erectile dysfunction), or trouble reaching orgasm
  • Sweating
  • Shakiness (tremors)

SSRIs have a boxed warning, the strictest warning from the US Food and Drug Administration (FDA). They have this warning because kids, teenagers, and young adults may have an increased risk of suicidal thoughts or behaviors when taking SSRIs. This risk may be highest in the first few weeks of treatment or right after changing drug dosages.4,8,9

These are not all the possible side effects of SSRIs. Talk to your doctor about what to expect when taking SSRIs. You should also call your doctor if you have any changes that concern you when taking SSRIs.

Other things to know

There are rare side effects or risks to consider with SSRIs. Your doctor will go over these rare side effects with you. If you notice any new symptoms you are not used to, seek medical guidance on how to proceed.2,4,9,10

Before taking an SSRI, tell your doctor if you are pregnant or planning to become pregnant. Some antidepressants can harm an unborn baby.1,4,8

Do not change the dose or stop taking an SSRI without first talking to your doctor. Stopping some SSRI drugs suddenly can lead to withdrawal symptoms. These may include nausea, dizziness, sleepiness, and feeling like you have the flu.4,9

Your doctor will monitor you closely for any mental health side effects when you start or change doses of an antidepressant. If you have thoughts of harming yourself or others, call or text the Suicide & Crisis Lifeline at 988 right away to speak with a crisis counselor. Or you can chat with a counselor online.11

Before beginning treatment for MDD, tell your doctor about all your health conditions and any other drugs, vitamins, or supplements you are taking. This includes over-the-counter drugs.

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