Selective serotonin reuptake inhibitors (SSRIs) for depression

Selective serotonin reuptake inhibitors (SSRIs) are the most commonly prescribed type of antidepressant medicines. SSRIs available in Australia include citalopram (Cipramil); escitalopram (Lexapro); fluoxetine (Prozac); fluvoxamine (Luvox); paroxetine (Aropax); and sertraline (Zoloft).

How they work

Serotonin is a brain chemical that activates nerve cells in the brain and plays a major role in regulating our mood. Doctors believe that the SSRI medicines relieve depression by making more serotonin available to activate nerve cells.

The main advantage of these medicines is that they do not cause as many side effects as some of the older tricyclic antidepressants, although they are not necessarily any more effective in the treatment of depression.

As well as being used for depression, many of the SSRIs are also used to treat some of the anxiety disorders such as obsessive-compulsive disorder, social anxiety disorder, panic disorder and post-traumatic stress disorder, as the role of serotonin in these conditions is also believed to be important.

Side effects

If you are prescribed an SSRI, you may experience some initial anxiety, nervousness and difficulty sleeping. These, and some other side effects such as nausea, diarrhoea, headache and dry mouth, generally pass with continued treatment, but it is important you talk to your doctor if they worry you.

Increased sweating can be an annoying side effect that may persist.

Sexual dysfunction — including reduced sexual interest, difficulty with erections (in men) and difficulty reaching orgasm (in men and women) — can occur in people taking these medicines. If this causes problems for you a medicine from another class might be prescribed.

Doctors advise that if someone has been taking these medicines for some time and they stop taking them suddenly, a withdrawal reaction can occur. Symptoms of this include nausea, dizziness, anxiety, headache and flu-like symptoms. To avoid this happening when you finish your treatment, your doctor may reduce the dose of the medicine slowly so that you don't experience any of these unpleasant effects.

Taking other medicines at the same time

SSRIs can interact with many other medicines (for example, medicines like warfarin used to treat clotting disorders and some medicines used for anxiety) and also with other antidepressants, such as the MAOI (monoamine oxidase inhibitors) antidepressants and the tricyclic antidepressants. Other medicines that affect serotonin levels, such as sumatriptan (brand name Imigran) and naratriptan (brand name Naramig), as well as tramadol (brand name Tramal) need to be avoided.

Interactions among drugs can cause bad reactions, so ask your doctor if you are in doubt. Even some complementary medicines, such as St John’s wort, may interact with antidepressants, so always tell your doctor if you are taking any.

When your doctor switches you from another antidepressant to an SSRI

If you have been taking a tricyclic or MAOI antidepressant and you start taking a SSRI instead, there will usually need to be a period of time (usually one to 2 weeks) between stopping the previous medicine and starting the new one. Ask your doctor if you are unsure of how this will affect you.

Last Reviewed: 19 December 2012


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3. Chapter 4.3.3. Selective serotonin re-uptake inhibitors. British National Formulary. London: BMJ Group; March 2011.


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