Antidepressants are used to treat clinical depression or stop it from coming back. You can also take them for other mental health conditions.
Antidepressants usually come as tablets.
Clinical depression - symptoms and treatment
How antidepressants work
Antidepressants work by increasing the levels of chemicals in the brain called neurotransmitters.
Some neurotransmitters can improve your mood and emotion. For example, serotonin and noradrenaline. But doctors are not very clear about how this works.
Neurotransmitters can also disrupt pain signals sent by nerves. This may explain why some antidepressants can help ease long-term pain.
Antidepressants may also work by boosting your immune response. This might be weaker if you have had depression for a long time.
Antidepressants can treat the symptoms of depression. But they do not always address its causes. They're usually used with other types of therapy to treat severe depression.
How well antidepressants work
Most people benefit from taking antidepressants.
They often relieve symptoms quickly, particularly in cases of severe depression. They may not work as well for mild depression.
Types of antidepressants
There are 4 main types of antidepressants.
Selective serotonin reuptake inhibitors (SSRIs)
SSRIs are the most commonly prescribed type of antidepressants. They cause fewer side effects than some of the others. They are also less likely to cause a serious overdose.
Examples of SSRIs include:
- citalopram (Ciprager, Cipramil, Citrol and Ciprotan)
- paroxetine (Parox and Seroxat)
- sertraline (Depreger, Lustral, Seretral, Serimel and Serlan)
- escitalopram (Esciprex, Escitalpro, Etalopro and Lexapro)
- fluoxetine (Prozac, Fluzac and Prozamel)
Serotonin-noradrenaline reuptake inhibitors (SNRIs)
SNRIs work in a similar way to SSRIs. Some people respond better to SNRIs than to SSRIs.
Examples of SNRIs include:
- duloxetine (Cymbalta, Yentreve and Loxentia)
- venlafaxine (Efexor, Ireven, Vedixal, Venex, Venlablue, Venlafex and Venlofex)
Tricyclic antidepressants (TCAs)
TCAs are not usually recommended as the first option for treating depression. This is because they can be more dangerous if you take more than you are prescribed. They can also cause more side effects than SSRIs and SNRIs - such as constipation, dry mouth and difficulty peeing.
Your doctor may prescribe a TCA if you have severe depression that does not respond to other treatments.
TCAs are also sometimes used for other conditions, such as obsessive compulsive disorder (OCD).
Examples of TCAs include:
- amitriptyline (Astilin)
- clomipramine (Anafranil)
- dosulepin (Prothiaden)
- lofepramine (Gamanil)
Some types of TCAs such as amitriptyline are prescribed for chronic nerve pain.
Monoamine oxidase inhibitors (MAOIs)
MAOIs are an older type of antidepressant that are rarely used nowadays. They may cause potentially serious side effects and are usually prescribed by a specialist doctor. Tranylcypromine (Parnate) is an example of a MAOI.
Other types of antidepressants
There are many other types of antidepressants. These are sometimes called atypical antidepressants.
Mirtazapine
Mirtazapine (Mirap, Zismirt, Zispin) is a noradrenaline and specific serotonergic antidepressant (NASSA).
This may be effective for some people who cannot take SSRIs. The side effects of NASSAs are similar to those of SSRIs, with fewer of the sexual problems linked to SSRIs.
Common side effects include dry mouth, increased appetite and weight gain, headaches and feeling sleepy.
Trazodone
Trazodone (Molipaxin) is a serotonin antagonist and reuptake inhibitor (SARI). This class of medicine is not usually the first choice of antidepressant.
They may be prescribed if other antidepressants have not worked or caused side effects.
Vortioxetine
Vortioxetine (Brintellix or Vortioxetine Clonmel) may be prescribed if other antidepressants have not worked.
Common side effects of vortioxetine include abnormal dreams, constipation, diarrhoea, dizziness, itching, nausea and vomiting.
Agomelatine
Agomelatine (Valdoxan or Agomelatine Viatris) is a melatonin receptor agonist and a selective serotonin-receptor antagonist. It is not usually a first choice of antidepressant. It may be prescribed if other antidepressants have not worked.
You will need to have your liver function checked before starting on agomlatine and while taking it.
Other types of treatment
There are other types of treatments for depression. They can be used on their own or along with antidepressants. These include talking therapies such as cognitive behavioural therapy (CBT).
Regular exercise can also help, especially if you have mild to moderate depression.
Content supplied by the NHS and adapted for Ireland by the HSE