SSRIs: What are they, Uses, Side Effects & More

By Terez Malka, MD
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July 21, 2021

Antidepressant medications have helped Americans manage their mental health symptoms for almost 50 years. They are among the most commonly prescribed psychiatric drugs in the country, with nearly 13% of adults in the United States taking at least one dose in the last 30 days.

There are many types of antidepressant drugs. One of the most commonly prescribed classes of these drugs are selective serotonin reuptake inhibitors, or SSRIs. These drugs are a popular treatment option for people experiencing depression, anxiety, and other psychiatric disorders. They work by boosting the serotonin levels in your brain and can help improve your mood, sleep, appetite, and ability to regulate your emotions. 

In this article, I’ll explore the science behind SSRIs and explain when and why healthcare providers prescribe them to patients. I will cover what SSRIs are, what they’re used for, and how they work. I’ll discuss how long it takes for these drugs to work, as well as side effects you might experience. I’ll provide a list of SSRI medications. I’ll share whether these drugs can cause withdrawal symptoms, if you should avoid alcohol while taking them, and whether SSRIs can cause weight gain. I’ll discuss potential alternatives to taking an SSRI, as well as safety issues and warnings for potential patients. Finally, I’ll share some information about whether you can get SSRIs online, and when you should speak to a doctor.

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What is an SSRI?

Selective serotonin reuptake inhibitors (SSRIs) are antidepressant drugs that treat patients with a wide variety of psychiatric disorders. SSRI medications are considered a first-line treatment for depression and other disorders because of their tolerability, effectiveness, and safety. 

SSRIs work by boosting the serotonin levels in your brain. Serotonin is a type of neurotransmitter, a molecule used by your nervous system to carry messages between neurons, between the nervous system and muscles, or between the nervous system and the brain. 

Under normal circumstances, serotonin conveys a message to a cell receptor, and then it is reabsorbed back into the body to be recycled. When someone takes an SSRI, the medication inhibits the “reuptake” process, increasing the body’s level of serotonin and giving it more opportunities to communicate. 

Serotonin helps humans think, learn, and remember. It also helps stabilize mood, balance emotions, regulate appetite, and improve sleep, among other things. Healthcare clinicians aren’t sure whether low levels of serotonin cause major depression and other mental illnesses or vice versa. We do know that using medications and other treatments to boost and rebalance serotonin levels can positively impact a patient’s mental well-being and quality of life.

What Are SSRIs Used for?

The U.S. Food and Drug Administration (FDA) has approved several selective serotonin reuptake inhibitors (SSRIs) to treat specific mental health conditions. This class of drugs helps patients manage symptoms related to:

Some healthcare practitioners will prescribe SSRIs “off-label” to treat conditions that fall outside the scope of psychiatry. Those conditions include migraines, fibromyalgia, diabetic neuropathy, neurocardiogenic syncope, premature ejaculation, among others. 

How Does an SSRI Work?

Selective serotonin reuptake inhibitors (SSRIs) increase and rebalance serotonin levels in your body by blocking your cell receptors from reabsorbing the neurotransmitter as they usually would. Though research is still ongoing, clinical trials suggest that 20% more patients saw an improvement in their depression symptoms when they took antidepressant medication like SSRIs compared with those who took a placebo.

SSRI medications are only one of a few different types of antidepressants. There are three other classes of reuptake inhibitor medications: serotonin and norepinephrine reuptake inhibitors (SNRIs), norepinephrine and dopamine reuptake inhibitors (NDRIs), and serotonin antagonist and reuptake inhibitor (SARIs). Each works to boost and redirect serotonin and/or other neurotransmitters to help people manage mental illness. 

Older antidepressants, like tricyclic antidepressants (TCAs) and monoamine oxidase inhibitors (MAOIs), are also effective for some patients. These older medications can come with an increased risk of adverse effects, though. 


Both SSRI and SNRI medications are reuptake inhibitors that block the body from reabsorbing neurotransmitters, increasing their availability. SSRIs only boost serotonin, while SNRIs increase both serotonin and norepinephrine, another neurotransmitter.

SSRI and SNRI medications treat many of the same conditions and share many common side effects. Some SNRIs are FDA-approved to treat physical ailments as well as depression, anxiety, and other psychiatric disorders. Studies suggest that patients who take SNRIs experience nausea, insomnia, and dry mouth more often than those who take SSRIs.


Instead of blocking the reuptake of serotonin as SSRI medications do, MAOIs boost serotonin and other neurotransmitters in the brain by inhibiting an enzyme that breaks them down. MAOIs are the oldest antidepressants on the market, but are now considered “last resort” medications. Many doctors feel more comfortable prescribing patients SSRIs as a first-line treatment because they are associated with fewer side effects and food or drug interactions. 

How Long Does it Take for an SSRI to Work?

Individual experiences with selective serotonin reuptake inhibitors (SSRIs) can be different. Although the medications begin to work immediately, it can take some time for a patient to feel the positive effects. Some people see an improvement in their symptoms within 1-2 weeks of treatment, though those cases are relatively atypical. Most individuals report noticing positive changes to their mood and well-being after 4-6 weeks of treatment.

If you have been taking an SSRI for some time and have not experienced significant symptom improvement, continue taking your medication as directed until you can talk to your doctor about adjusting your treatment plan. They may suggest increasing your dosage until it is more effective or gradually tapering off your regimen until you can switch medications without difficulty.

Side Effects

Like other antidepressants, selective serotonin reuptake inhibitors (SSRIs) can cause side effects in certain patients. The most common side effects of SSRIs include: 

Some patients experience sexual dysfunction as a result of taking an SSRI. Typical issues include a lowered libido, greater difficulty achieving orgasm, and, among male patients, greater difficulty achieving or maintaining an erection.

List of SSRI Medications

Seven SSRI medications are FDA-approved to treat patients with depression, anxiety disorders, and other psychiatric issues in the United States. They include: 

  • Citalopram (Celexa): Citalopram is approved to treat adults with depression, anxiety, and other mood disorders.
  • Escitalopram (Lexapro): Escitalopram is approved to treat adults with major depressive disorder (MDD) and generalized anxiety disorder (GAD), as well as pediatric patients with MDD ages 12 and older.
  • Fluoxetine (Prozac, Sarafem, Symbyax): Fluoxetine is approved to treat adults with MDD, obsessive-compulsive disorder (OCD), bulimia nervosa, premenstrual dysphoric disorder (PMDD), and panic disorder. It can also be combined with other medications to treat depressive episodes related to bipolar disorder and treatment-resistant depression. Fluoxetine can also be safely prescribed for pediatric patients over eight years old with MDD and OCD patients older than seven.
  • Fluvoxamine (Luvox, Luvox CR): Fluvoxamine is approved to treat patients over 8 years of age suffering from OCD.
  • Paroxetine (Paxil, Paxil CR, Pexeva): Paroxetine is approved for MDD, OCD, GAD, social anxiety disorder (SAD), panic disorder, post-traumatic stress disorder (PTSD), and premenstrual dysphoric disorder (PMDD).
  • Sertraline (Zoloft): Sertraline hydrochloride is approved to treat MDD, OCD, panic disorder, PTSD, SAD, and PMDD. It is also approved to treat children with OCD who are six years old or older.
  • Vilazodone (Viibryd): Vilazodone is approved to treat MDD in adults.

Do SSRIs Cause Withdrawal Symptoms? 

If you stop taking your selective serotonin reuptake inhibitor (SSRI) too abruptly, it can cause you to experience discontinuation syndrome, or withdrawal symptoms. Common symptoms include fatigue, nausea, muscle aches, agitation, irritation, anxiety, sensory disturbances like hallucinations and tingling, insomnia or vivid dreams, sweating, and blurry vision.

These symptoms are not life-threatening and should only last for 1-2 weeks after you stop taking your medication. You can avoid discontinuation syndrome by talking to your doctor about gradually decreasing your dosage so that you can gently taper off your medication without adverse effects.

Can You Drink Alcohol While Taking an SSRI?

There is no evidence that selective serotonin reuptake inhibitors (SSRIs) interact poorly with alcohol, so it is presumed safe for you to drink while taking your medication. Healthcare providers suggest taking extra precautions when mixing SSRIs and alcohol as both have the propensity to cause some patients to feel drowsy.

Do SSRIs Cause Weight Gain?

Selective serotonin reuptake inhibitors (SSRIs) can affect patients in different ways. Some people put on weight while taking their medication; some lose their appetite or lose weight instead. Many patients maintain their weight while taking SSRIs without difficulty. 

If you are concerned about gaining weight while taking your SSRI, talk to your doctor about whether the benefits of the medication outweigh the costs and what lifestyle and other changes you can make to mitigate this potential side effect.

Are There Alternatives to SSRIs?

There are many treatment options that patients can use to manage their mental health symptoms and find relief. Selective serotonin reuptake inhibitors (SSRIs) are one class of effective medications. Others include: 

  • Selective serotonin & norepinephrine inhibitors (SNRIs)
  • Tetracyclic antidepressants 
  • Tricyclic antidepressants
  • Aminoketone antidepressants like bupropion (Wellbutrin
  • Monoamine oxidase inhibitors (MAOIs)
  • NMDA receptor antagonist medications
  • Benzodiazepines for anxiety disorders

Good lifestyle habits can also help mitigate your symptoms and improve your quality of life. Getting enough sleep, sunlight, social engagement, and exercise can help you relax and reset. Avoiding alcohol and caffeine can be beneficial, as can seeking out psychotherapy or psychiatric support groups.


Healthcare professionals have been prescribing selective serotonin reuptake inhibitors (SSRIs) to patients for nearly 50 years. They are considered a safe, effective, and tolerable front-line treatment for most patients with symptoms of depression, anxiety, and other psychiatric disorders. 


Selective serotonin reuptake inhibitor (SSRI) medications can interact poorly with other prescription drugs and over-the-counter treatments, including some homeopathic remedies like St. John’s Wort. In rare cases, certain drugs can combine to induce serotonin syndrome, a severe condition that can cause tremors, seizures, and death. Be sure to talk to your doctor about all medications and supplements you take before beginning a new antidepressant regimen.

Some studies have shown that when pregnant women take antidepressants like specific SSRIs, the medication can harm fetal development. If you are pregnant or breastfeeding, talk to your doctor about the costs and benefits of being on an SSRI and whether the medication is the best option for you.

Some SSRIs carry the rare but serious risk of increasing suicidal thoughts and behaviors in pediatric patients and young adults. If you believe that you or someone you know may harm themselves or others, call 9-1-1 or immediately visit the nearest emergency room.

Can someone with bipolar disorder take an SSRI?

Some doctors prescribe specific selective serotonin reuptake inhibitors (SSRIs) combined with other mood stabilizer drugs to help patients with bipolar disorder manage their symptoms. Antidepressants can exacerbate mood cycling in some patients, though, so your doctor may need to adjust your medication if you begin to experience a manic episode.

Can You Get SSRIs Online?

To purchase a selective serotonin reuptake inhibitor (SSRI), you must see a doctor and get a prescription. Reputable online doctors can assess you, diagnose your condition, and prescribe an appropriate medication, including an SSRI, to meet your needs. 

Once you have your prescription, you can purchase your SSRI from an online pharmacy and have your medication shipped directly to your door.

Talk to a doctor online

Refill medications and get certain necessary prescriptions.

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When to Speak to a Doctor

You do not have to live with depression, anxiety, or another mental health condition. Effective treatment options are available that can help dramatically improve your quality of life. 

If you have intense, distressing symptoms that impact your day-to-day functioning, or have persisted for more than two weeks, call your doctor or psychiatrist to make an appointment. They will screen you for mental health conditions, test for any physical conditions that could be contributing to your emotional state, and help you find a treatment plan that works for you.

You can start controlling your depression and anxiety and get access to the treatment you need with K Health. Starting at $49/month, get prescriptions for mental health medications plus unlimited doctor visits through the K Health app. Start your free assessment here.

Frequently Asked Questions

What does SSRI stand for?
SSRI stands for selective serotonin reuptake inhibitors. SSRIs are commonly prescribed antidepressant drugs that treat patients with a wide variety of psychiatric disorders.
Do SSRIs work for anxiety?
Some SSRI medications are FDA-approved to treat specific anxiety disorders. For example, Escitalopram (Lexapro), Fluoxetine (Prozac, Sarafem, Symbyax), Fluvoxamine (Luvox, Luvox CR), Paroxetine (Paxil, Paxil CR, Pexeva), and Sertraline hydrochloride (Zoloft) are all each used to treat anxiety disorders.
Which SSRI is best for anxiety?
SSRI medications work differently for different people. Talk to your doctor about how best to treat the anxiety symptoms you are experiencing.
How to get off SSRIs?
If you stop taking selective serotonin reuptake inhibitors (SSRIs) too abruptly, it can cause you to experience withdrawal symptoms. These symptoms are not life-threatening, but you can avoid experiencing them entirely by talking to your doctor about how to gently taper off your medication.

K Health articles are all written and reviewed by MDs, PhDs, NPs, or PharmDs and are for informational purposes only. This information does not constitute and should not be relied on for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment.

Terez Malka, MD

Dr. Terez Malka is a board-certified pediatrician and emergency medicine physician.

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