Our rating
Adults 3 smilies: This treatment is very useful. It is strongly supported as effective by scientific evidence.
Children and adolescents: for fluxetine 1 smiley: This treatment is promising and may be useful. It has some evidence to support it, but more evidence is needed to be sure it works.
for other antidepressants No smiley: On the available evidence, this treatment does not seem to be effective.


The rating system

  • 3 smiliesThese treatments are very useful. They are strongly supported as effective by scientific evidence.
  • 2 smiliesThese treatments are useful. They are supported by scientific evidence as effective, but the evidence is not as strong.
  • 1 smileyThese treatments are promising and may be useful. They have some evidence to support them, but more evidence is needed to be sure they work.
  • No smiley On the available evidence, these treatments do not seem to be effective.
  • Question markThese treatments have not been properly researched. It is not possible to say whether they are useful or not.
  • Exclamation MarkSafety or other concerns have been raised for the use of these treatments.

What are they?

Antidepressants are medications designed to treat depression. They can only be prescribed by a doctor. Some antidepressants are also used to treat psychological disorders other than depression, including anxiety.

There are several different classes (types) of antidepressants. Each of these classes includes several different drugs. The main classes of antidepressants are listed below, along with common medications (the chemical name) and their brand names (the label they are sold under).

The tricyclics and the MAOIs are older classes of antidepressants, with the MAOIs seldom used these days. SSRIs are the most commonly prescribed type of antidepressant at the moment.

How do they work?

Antidepressants work by changing the level of neurotransmitters (chemical messengers) in the brain. Several neurotransmitters are thought to be in low supply in depression, including noradrenaline (sometimes called norepinephrine) and serotonin. It is thought that increasing the levels of these neurotransmitters can be helpful in depression.

Tricyclics mainly increase the level of noradrenaline in the brain. The SSRIs work by increasing the supply of serotonin only. The SNRIs and RIMAs increase the supply of both serotonin and noradrenaline in the brain. MAOIs increase the availability of both serotonin and dopamine.

Some newer types of antidepressants work in different ways.

Most antidepressants need to be taken for at least 6 to 9 months after symptoms disappear. Stopping an antidepressant too early increases the chances of depression symptoms returning.

Are they effective?

There are a very large number of studies showing that antidepressants work better than placebos (dummy pills) for adults with moderate to severe depression. Tricyclic antidepressants, SSRIs and RIMAs work equally well. The best effects come from combining an antidepressant with a psychological therapy, such as cognitive behaviour therapy.

Some people may not respond to the first antidepressant they are prescribed (i.e. it does not reduce their depression symptoms). However, they may respond well to another antidepressant of the same type, or one of a different type.

Tricyclics do not appear to work for children and have only limited effects on adolescents. There is some evidence that the SSRI fluoxetine is effective in children and adolescents. However, other SSRIs are not advised in children and adolescents because of safety concerns.

Are there any disadvantages?

Click each section below to read more about the potential disadvantages of antidepressants.

  • Antidepressant drugs can have side effects. Some types of antidepressants are more likely to cause side effects (or have more specific side effects) than other types. Side effects can include:

    • Sleep problems, including sleeping too much or too little
    • Dizziness when standing
    • Feeling tired during the day
    • Dry mouth
    • Agitation and/or restlessness
    • Tremor (slight shake of muscles of arms and hands)
    • Difficulty passing urine
    • Weight gain or loss
    • Nausea and vomiting
    • Headaches
    • Digestive problems (including constipation and diarrhoea)
    • Reduced sex drive and difficulty reaching orgasm

    This list of side effects may seem long, but not everyone will experience the same side effects and some often disappear within a few weeks. If you are concerned about any side effects you experience while taking antidepressants, make sure to talk to your doctor or pharmacist.

  • Contrary to what many people believe, antidepressants are not at all addictive. But, they can cause some withdrawal effects if you stop taking them abruptly. For this reason, most antidepressants require you to gradually lower the dose before stopping them entirely.

  • Antidepressants usually take two to four weeks to have an effect. It is important not to give up on them too early. Some people don’t respond well to the first antidepressant they try, so their doctor may need to prescribe a few different ones before they find a medication which works for them.

  • Some antidepressants must not be taken if you are also taking other medication. SSRIs are harmful if taken at same time, or soon after, using MAOIs. If you are taking any other medications or supplements, whether for depression or another condition, you should tell your doctor or pharmacist before taking antidepressants.

  • Several SSRI antidepressants may be unsafe for use by children and adolescents because they have been associated with an increased risk of suicidal thoughts. If you start having suicidal thoughts while taking antidepressant medication make sure to tell your doctor or pharmacist.

  • A number of medications and drugs can cause a dangerous increase in blood pressure when taken with a MAOI. These include other antidepressants, stimulant drugs, cold and hayfever medications, nasal decongestants, local anaesthetics and illicit drugs. If you are taking MAOIs it is important you tell this to anyone prescribing you medicines.MAOIs should always be taken under the close supervision of a health care professional.

    Some foods contain tyramine which can raise blood pressure when taking MAOIs. If you are taking MAOIs you should check with your doctor what these foods are. It is important to avoid these foods because they can cause serious problems.

Where do you get them?

Antidepressants can be prescribed by a doctor, including GPs and psychiatrists.


Antidepressants are one of the best treatments available for depressed adults, but caution is advised for children and adolescents. For adults, antidepressants can be combined with a psychological treatment for even better results.

Key references

  • Arroll B, Elley CR, Fishman T, Goodyear-Smith FA, Kenealy T, Blashki G, et al. Antidepressants versus placebo for depression in primary care. Cochrane Database of Systematic Reviews. 2009 (3).
  • Cipriani A, Furukawa TA, Salanti G, Chaimani A, Atkinson LZ, Ogawa Y, et al. Comparative efficacy and acceptability of 21 antidepressant drugs for the acute treatment of adults with major depressive disorder: a systematic review and network meta-analysis. The Lancet. 2018; 391(10128):1357-66.
  • Cox GR, Callahan P, Churchill R, Hunot V, Merry SN, Parker AG, et al. Psychological therapies versus antidepressant medication, alone and in combination for depression in children and adolescents. Cochrane Database of Systematic Reviews. 2014 (11).
  • Furukawa TA, McGuire H, Barbui C. Low dosage tricyclic antidepressants for depression. Cochrane Database of Systematic Reviews. 2003 (3).
  • Gartlehner G, Wagner G, Matyas N, Titscher V, Greimel J, Lux L, et al. Pharmacological and non-pharmacological treatments for major depressive disorder: review of systematic reviews. BMJ Open. 2017;7(6):e014912-e.
  • Hetrick SE, McKenzie JE, Cox GR, Simmons MB, Merry SN. Newer generation antidepressants for depressive disorders in children and adolescents. Cochrane Database of Systematic Reviews. 2012 (11).
  • Linde K, Kriston L, Rucker G, Jamil S, Schumann I, Meissner K, et al. Efficacy and acceptability of pharmacological treatments for depressive disorders in primary care: systematic review and network meta-analysis. Annals of family medicine. 2015; 13(1): 69-79.
  • Moncrieff J, Wessely S, Hardy R. Active placebos versus antidepressants for depression. Cochrane Database of Systematic Reviews. 2004 (1).
  • Mottram PG, Wilson K, Strobl JJ. Antidepressants for depressed elderly. Cochrane Database of Systematic Reviews. 2006 (1).

Last reviewed and updated: 20 December 2023