Merck Manual

Please confirm that you are not located inside the Russian Federation

honeypot link
Drugs Used to Treat Depression

Drugs Used to Treat Depression


Some Side Effects


Selective serotonin reuptake inhibitors (SSRIs)








Sexual dysfunction (primarily, delayed orgasm but also loss of desire and erectile dysfunction Erectile Dysfunction (ED) Erectile dysfunction (ED) is the inability to attain or sustain an erection satisfactory for sexual intercourse. (See also Overview of Sexual Dysfunction in Men.) Every man occasionally has... read more in some people), nausea, diarrhea, headache, weight loss (short-term), weight gain (long-term), discontinuation syndrome*, forgetfulness, blunting of emotions, and easy bruising

SSRIs are the most commonly used class of antidepressants. They are also effective for generalized anxiety disorder Generalized Anxiety Disorder Generalized anxiety disorder consists of excessive nervousness and worry about a number of activities or events. People have anxiety more days than not over a period of 6 months or longer. The... read more , obsessive-compulsive disorder Obsessive-Compulsive Disorder (OCD) Obsessive-compulsive disorder is characterized by obsessions, compulsions, or both. Obsessions are recurring, persistent, unwanted, anxiety-provoking, intrusive ideas, images, or urges. Compulsions... read more , panic disorder Panic Attacks and Panic Disorder A panic attack is a brief period of extreme distress, anxiety, or fear that begins suddenly and is accompanied by physical and/or emotional symptoms. Panic disorder involves recurrent panic... read more , phobic disorder Specific Phobias Specific phobias involve persistent, unrealistic, intense anxiety about and fear of specific situations, circumstances, or objects. The anxiety caused by a phobic disorder can interfere with... read more , posttraumatic stress disorder Posttraumatic Stress Disorder (PTSD) Posttraumatic stress disorder (PTSD) involves intense, unpleasant, and dysfunctional reactions after an overwhelming traumatic event. Events that threaten death or serious injury can cause intense... read more , premenstrual dysphoric disorder Premenstrual dysphoric disorder Depression is a feeling of sadness and/or a decreased interest or pleasure in activities that becomes a disorder when it is intense enough to interfere with functioning. It may follow a recent... read more , and bulimia Bulimia Nervosa Bulimia nervosa is an eating disorder characterized by the repeated rapid consumption of large amounts of food (binge eating), followed by attempts to compensate for the excess food consumed... read more .

Toxicity due to overdosage is less serious than that with other antidepressants.

Norepinephrine-dopamine reuptake inhibitors


Headache, agitation, discontinuation syndrome*, high blood pressure in a few people, and rarely seizures

Serotonin modulators (5-HT2 blockers)


Drowsiness and weight gain

Mirtazapine does not cause nausea or sexual dysfunction.


Serotonin-norepinephrine reuptake inhibitors





Nausea, dry mouth, discontinuation syndrome*, and, if high doses are taken, an increase in blood pressure

Most of the side effects can be prevented or minimized when low doses are used and when changes in dosages are made slowly.

Heterocyclic (including tricyclic) antidepressants

  • Amitriptyline

  • Amoxapine

  • Clomipramine

  • Desipramine

  • Doxepin

  • Imipramine

  • Maprotiline

  • Nortriptyline

  • Protriptyline

  • Trimipramine

Drowsiness, weight gain, increased heart rate and decreased blood pressure when a person stands ( orthostatic hypotension Dizziness or Light-Headedness When Standing Up In some people, particularly older people, blood pressure drops excessively when they sit or stand up (a condition called orthostatic or postural hypotension). Symptoms of faintness, light-headedness... read more ), dry mouth, confusion, blurred vision, constipation, difficulty starting to urinate, delayed orgasm, and discontinuation syndrome*

With clomipramine and maprotiline, seizures

These drugs are usually not prescribed for older people because side effects are usually more pronounced in them.

Overdosage can cause serious, potentially life-threatening toxicity.

Monoamine oxidase inhibitors (MAOIs)

  • Isocarboxazid

  • Phenelzine

  • Selegiline

  • Tranylcypromine

Insomnia, nausea, weight gain, sexual dysfunction (loss of desire, delayed orgasm, and erectile dysfunction Erectile Dysfunction (ED) Erectile dysfunction (ED) is the inability to attain or sustain an erection satisfactory for sexual intercourse. (See also Overview of Sexual Dysfunction in Men.) Every man occasionally has... read more ), pins-and-needles sensation, dizziness, decreased blood pressure (particularly when a person stands), and discontinuation syndrome*

People who take these drugs must follow dietary restrictions and avoid using certain drugs to avoid a serious reaction involving a sudden, severe increase in blood pressure with a severe, throbbing headache (hypertensive crisis).

Selegiline is available as a patch. With the patch, people do not have to follow the dietary restrictions unless the patch contains a high dose.


  • Dextroamphetamine

  • Methylphenidate

Nervousness, tremor, insomnia, and dry mouth

These drugs are usually used with antidepressants. Used alone, they are usually ineffective as antidepressants.

Melatonergic antidepressant


Headache, nausea, and diarrhea

Agomelatine has fewer side effects than most antidepressants. It does not cause daytime drowsiness, insomnia, weight gain, or sexual dysfunction.

Agomelatine may increase liver enzyme levels. These levels should be measured before therapy is started and every 6 weeks thereafter.

Ketamine-like drugs


Dizziness, increased blood pressure, feeling of detachment

Esketamine is related to the anesthetic ketamine.

Esketamine is used in combination with other oral antidepressants for treatment-resistant depression.

Esketamine is available as a nasal spray

* Discontinuation syndrome consists of dizziness, anxiety, irritability, fatigue, nausea, chills, and muscle aches that occur when a drug is stopped abruptly.