Antidepressants

What are antidepressants?

Antidepressants are medicines used to treat mental health conditions including:

• depression
• anxiety
• eating disorders
• obsessive-compulsive disorder
• post-traumatic stress disorder

Medicine is just one strategy used to treat depression and anxiety conditions. Other treatments may also be needed, such as psychological treatments (talking therapy) or lifestyle changes.

How do antidepressants work?

Antidepressants affect several chemicals in the brain (neurotransmitters) that influence mood and anxiety, including:

• serotonin
• noradrenaline
• dopamine
• melatonin

Because of how they work, you may need to take antidepressants for a while before you see your symptoms improve.

If you have depression, you may begin to feel better 2 to 4 weeks after starting an antidepressant medication, but it can take up to 6 to 8 weeks to feel the full effect.

If you have an anxiety disorder, it may take 4 to 6 weeks before you start feeling better. It may take up to 12 weeks to feel the full effect.

In some people, antidepressants are not effective, no matter how long they take them for.

What types of antidepressants might I be prescribed?

There are many different types of antidepressants. They are grouped according to how they work in the body. Within each group, there are several different medicines that work in a similar way.

• Selective serotonin reuptake inhibitors (SSRIs) are the most commonly prescribed antidepressant class in Australia. While they are not necessarily more effective than others, they are usually well-tolerated by most people, which means that most people find that side effects are not too troublesome. Examples of this class of antidepressants include citalopram, escitalopram, fluoxetine, fluvoxamine, paroxetine and sertraline.
• Serotonin and noradrenaline reuptake inhibitors (SNRIs) have fewer side effects than SSRIs and may be used for more severe depression. They include duloxetine, venlafaxine and desvenlafaxine.
• Noradrenaline reuptake inhibitors (NARIs) work on noradrenaline and are less likely to cause drowsiness than other classes. This class includes reboxetine.
• Tricyclic antidepressants (TCAs) are less commonly prescribed today, as they are associated with more harmful side effects than newer medicines. They include amitriptyline, nortriptyline, clomipramine, dothiepin, doxepin, imipramine and trimipramine.
• Reversible inhibitors of monoamine oxidase A (RIMAs) are more commonly used to treat anxiety than depression. They include moclobemide.
• Noradrenalin-serotonin specific antidepressants (NaSSAs) are a relatively new class with fewer sexual side effects but can cause weight gain. This class includes mirtazapine.
• MAOIs (monoamine oxidase inhibitors) are rarely prescribed today due to their risk of side effects. They include phenelzine and tranylcypromine.
• ‘Atypical’ antidepressants that don’t easily fit into the classes above, and include agomelatine and vortioxetine. Agomelatine stimulate melatonin receptors to affect mood. Vortioxetine works on serotonin receptors, but in a different way to SSRIs and SNRIs.

Read more on a specific antidepressant medicine by searching the name in the online healthdirect Medicines tool.

What are the side effects or risks associated with antidepressants?

Like all medicines, antidepressants may have side effects. For most people, the side effects are not bad enough that they need to stop taking the medicine.

Different people may experience different side effects, so it’s important to talk to your doctor about your personal situation. Some people experience no side effects at all.

Side effects differ between antidepressants. Some antidepressant side effects may include:

• headaches and dizziness
• nausea
• weight gain
• anxiety or restlessness
• difficulty sleeping, or excessive sleepiness
• sexual problems, such as a low sex drive

Some of these side effects improve as your body gets used to the medicine.

It’s a good idea to ask your doctor or pharmacist about any common side effects associated with the antidepressant you have been prescribed.

Suicide risk when starting antidepressants

Some people, especially children and young people, can experience an increase in suicidal thoughts when they start taking antidepressants. This generally resolves over time as the medicine starts to work.

If someone you care about is starting antidepressants, it’s a good idea to look out for signs of suicidal thoughts or plans. If you are starting antidepressants yourself, think about what you can do to keep yourself safe if you start thinking about suicide.