What Are SSRIs?

Medically Reviewed by Jennifer Robinson, MD on May 02, 2023
4 min read

Everyone feels down from time to time. But for people with depression, the feelings of sadness can be so severe that they interfere with everyday life. It can become hard to function at home or at work, and the feelings can lead to a variety of physical and emotional problems.

However, depression is one of the most treatable mental disorders. Between 80% and 90%of people who have it benefit from treatment. The kind of management you need depends on your specific situation, but for some people, medication can be very helpful.

That’s because brain chemistry may contribute to the condition, so taking antidepressants can actually change your brain chemistry and help you feel better.

The most common antidepressants are called selective serotonin reuptake inhibitors (SSRIs). They’re considered relatively safe and cause fewer side effects than other kinds of medications used to treat depression.

SSRIs work by enhancing the function of nerve cells in the brain that regulate emotion. Information is communicated between your brain cells with signals. The chemical messengers that deliver these signals are called neurotransmitters. Serotonin is one type of neurotransmitter.

When these brain cells (called neurons) send signals to one another, they release a little bit of a neurotransmitter so that the message can be delivered. They then have to take back the neurotransmitter they released so they can send the next message. This process of replacing the neurotransmitter is called “reuptake.”

If you’re struggling with depression, the areas of your brain that regulate mood and send messages using serotonin might not function properly. SSRIs help make more serotonin available by blocking the reuptake process. This allows serotonin to build up between neurons so messages can be sent correctly. They’re called “selective” serotonin reuptake inhibitors because they specifically target serotonin.

The FDA is in charge of deciding which medications are safe and effective for which reasons. The following SSRIs are approved to treat depression, anxiety, and other mood disorders:

Most people who use SSRI antidepressants don’t have major problems, but every kind of medical treatment carries some risk. The possible side effects of these antidepressants include:

Some people, especially children and young adults, may be more likely to have suicidal thoughts when they take SSRIs. Studies show that when compared to results from taking a placebo, chances of having suicidal thoughts doubled -- from between 1% and 2% to between 2% and 4% -- when taking any kind of antidepressant, including an SSRI. If you have thoughts of hurting yourself while taking an SSRI, call 911.

There are also important safety issues to consider about SSRIs. Although it’s rare, if too much serotonin accumulates in your system, you can develop a condition called serotonin syndrome. This happens most often if two different medications that increase serotonin are combined.

SSRIs can also have dangerous interactions with some medicines, both prescription and over-the-counter, including herbs and supplements. Before starting on an SSRI, make sure to tell your doctor all the different kinds of medications and supplements you're taking.

Since all SSRIs work in a similar way, the side effects tend to be similar no matter what kind you take. But each SSRI has a different chemical makeup, so it’s possible that if you’re having side effects from one, you may not experience as many or any at all if you switch to another.

While some people do have side effects, others do not, and in many cases, the side effects disappear after a few weeks of treatment. It’s important to work with your doctor to find a medication that’s right for you.

Everyone is different when it comes to seeing improvements on SSRIs. But people typically start noticing positive changes after about 4 to 6 weeks of treatment. It can take several months to feel the full effect of the medication.

But if you’re not feeling any improvements after about 6 to 8 weeks, talk to your doctor about trying another treatment or adjusting your dosage.

Even though SSRIs aren’t habit-forming, it can be dangerous to stop them suddenly or miss several doses in a row. Doing this can lead to a condition called discontinuation syndrome that causes withdrawal-like symptoms.

If you do experience discontinuation syndrome, you might start to feel like you have the flu and/or notice symptoms like:

That’s why it’s important to work up to your prescribed dosage slowly with the help of your doctor, and to step down gradually if you agree it’s time to stop.

Show Sources


APA: “What Is Depression?”

HelpGuide.org: “Types of Antidepressants and Their Side Effects.”

Mayo Clinic: “Depression (major depressive disorder).”

NIH: “SSRI Research.”

FDA: “Selective Serotonin Reuptake Inhibitors (SSRIs) Information.”

Harvard Health Publications: “What are the real risks of antidepressants?”

Am Fam Physician: “What to do when SSRIs fail: eight strategies for optimizing treatment of panic disorder.”

Psych Central: “How Long Do Antidepressants Take to Work?”

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