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What are some common side effects of antidepressants?

Medically reviewed by Last updated on Aug 25, 2023.

Official answer


The most common side effects of antidepressants are drowsiness and fatigue, gastrointestinal side effects such as nausea, sexual dysfunction, weight gain, and risk of suicide.

Drowsiness and Fatigue

Drowsiness and dizziness are more common with tricyclic antidepressants (TCAs) or monoamine oxidase inhibitors (MAOIs) than selective serotonin reuptake inhibitors (SSRIs). Most people become tolerant to this effect. Some antidepressants can cause insomnia.

Gastrointestinal side effects

Most people feel a bit nauseous when they first start taking an antidepressant, but this usually goes away after a few weeks. Constipation, diarrhea, and a dry mouth may also occur, usually temporarily.

Sexual dysfunction

Antidepressants may reduce your sex drive (libido) or your ability to obtain or keep an erection if you are a man or reach orgasm (both male and female).

Weight gain

Once your symptoms of depression have resolved, your appetite usually improves. This may be the reason behind weight gain with antidepressants, or it could be due to fluid retention. Some antidepressants are more likely to cause weight gain than others.

Risk of suicide

All antidepressants have been associated with an increased risk of suicidal thoughts and behaviors, particularly in children and adolescents under the age of 25 years. This is more common within the first few weeks of starting an antidepressant. You should tell your doctor if you feel like your mood has gotten worse or if you are having suicidal thoughts.

Antidepressants are used for several mood-related disorders, not only depression, usually in combination with other treatments, such as talk therapy.

They are thought to work by altering the balance of chemicals in the brain called neurotransmitters, such as serotonin, norepinephrine, and/or dopamine. While altering these chemicals relieves symptoms of depression such as low mood, irritability, feelings of worthlessness, anxiety, and difficulty in sleeping, it does mean they can cause a range of side effects.

For more information see Antidepressants: Get tips to cope with side effects.

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