There is a lot of misinformation about antidepressant medication and there is no simple explanation as to how it works. Medication can be important in the treatment of moderate to severe depression and in some anxiety conditions. This fact sheet looks at what antidepressants do, how they work and where to get more information and help.

How do antidepressants work?

Research shows that more severe forms of depression are associated with specific changes in the brain, including changes to some hormones and chemical message systems. In these forms of depression, there are alterations in the activity of the brain in areas which may cause a major depressive episode. This is associated with the symptoms and disability seen with depression. Antidepressant medication is thought to influence the activity of serotonin and noradrenaline in some areas of the brain. However, depression is not simply a deficiency of these chemicals. Different types of antidepressants work in slightly different ways, but they all have an influence on parts of the brain related to emotions and motivation.

When is antidepressant medication used?

Antidepressant medication may be prescribed, along with psychological treatments, when a person experiences a moderate to severe episode of depression. Sometimes, antidepressants are prescribed when other treatments have not been successful or when psychological treatments are not possible due to the severity of the illness or a lack of access to the treatment. People with more severe forms of depression (bipolar disorder and depression with psychosis) do generally need to be treated with medication. This may include one or a combination of mood stabilisers, anti-psychotic drugs and antidepressants.

Which antidepressants are the most useful?

Making a decision about which antidepressant is best for a person can be complex. The decision is made in consultation with a doctor, after careful assessment and consideration. People can help the doctor's assessment by providing as much information as possible about themselves and their medical history. Important factors include the person's age, symptoms, other medications and, if female, whether they are pregnant or breastfeeding. There are many different types of antidepressant medication which have been shown to work, but their effectiveness differs from person to person. Your doctor may wish to prescribe a particular antidepressant to tailor it to your particular symptoms. Antidepressants take at least two weeks before they start to help, and it may also take some time for the doctor to find the most suitable medication and dosage.


Depression is common and can affect people of all ages, however, generally medication is not recommended as the first choice for the treatment of depression in children and young people.

The Therapeutic Goods Administration (Australia's regulatory agency for medical drugs) and manufacturers of antidepressants do not recommend antidepressant use for depression in young people under the age of 18. There are, however, no government (i.e. Pharmaceutical Benefits Scheme) restrictions placed on the prescription of antidepressants and doctors are not prevented from prescribing them if they feel they are needed.

There is concern that a small percentage of young people up to the age of 24 years taking Selective Serotonin Reuptake Inhibitors (SSRIs) for the treatment of depression may experience an increase in suicidal thoughts and behaviour. Research shows the risk to be roughly 4 per cent compared to 2 per cent for those taking a placebo dummy pill).

A young person will require close medical supervision and monitoring in the early stages of treatment if an antidepressant is prescribed.

Chronic Illness

Like any medication, antidepressants can produce side-effects. In some cases, taking antidepressants can affect existing symptoms or treatments for other illnesses. It is important for people to let doctors know about any illness they may have and any medication they are taking.

Pregnancy and breastfeeding

The decision to take medication while pregnant or breastfeeding is an individual one. It should be made in consultation with a doctor after considering the risks and benefits to both the mother and baby. The lowest effective dose should be used.

If a woman is breastfeeding, generally specific types of medications are preferred. While a number of factors will influence the choice of antidepressant, a group of antidepressants called tricyclics, as well as sertraline, citalopram and fluvoxamine are most commonly prescribed for women who are breastfeeding.

Studies show that paroxetine is generally not recommended at this time.

Antidepressants and bipolar disorder

People who have bipolar disorder and experience an episode of depression will often be given a mood stabiliser alone. It can take time for mood stabilisers to work. Sometimes antidepressants are used along with mood stabilisers to help ease the symptoms.

Antidepressant medication is generally not recommended for use by itself in people with bipolar disorder as it can trigger mania.

"I resisted medication for years; inaccurately believing it was 'weak' or I would turn into a 'vegetable'. Many misconceptions exist regarding medication. In my case, medication propelled my recovery and helped me to utilise psychological treatments effectively." April, 25

Types of antidepressants

There are many different types of antidepressant medication. Your doctor may need to find the medication and dose which is most effective for you. Keep in mind antidepressants take time before they start to help (at least two weeks). Below is a description of the different classes of antidepressants. Please note, this list only includes the generic medication names and not the pharmaceutical brand names. Please look on your medication packaging to find the name of the medication you are taking (this is usually written in lowercase).

There are differences in effects and side-effects of the antidepressants listed below, which can be discussed with your prescribing health professional.

Selective Serotonin Reuptake Inhibitors (SSRIs)

This class includes sertraline; citalopram; escitalopram; paroxetine; fluoxetine; fluvoxamine. SSRIs are:

  •   the most commonly prescribed antidepressants in Australia
  •   often a doctors' first choice for most types of depression
  •   generally well tolerated by most people
  •   generally non-sedating.

Serotonin and Noradrenalin Reuptake Inhibitors (SNRIs)

This class includes venlafaxine; desvenlafaxine; duloxetine. SNRIs:

  •   have fewer side-effects compared to the older antidepressants (such as TriCyclic Antidepressants)
  •   are often prescribed for severe depression
  •   are safer if a person overdoses.

    Reversible Inhibitors of MonoAmine oxidase (RIMAs)

    The class includes moclobemide. RIMAs:

    •   have fewer side-effects
    •   are non-sedating
    •   may be less effective in treating more severe forms of depression than other antidepressants
    •   are helpful for people who are experiencing anxiety or sleeping difficulties.

    TriCyclic Antidepressants (TCAs)

    The class includes nortriptyline; clomipramine; dothiepin; imipramine; amitriptyline. TCAs are:

    •   effective, but have more harmful side-effects than newer drugs (i.e. SSRIs)
    •   more likely to cause low blood pressure - so this should be monitored by a doctor
    •   more risky if a person were to overdose.

    Noradrenaline-Serotonin Specific Antidepressants (NaSSAs)

    This class includes mirtazapine. NaSSAs are:

    •   helpful when there are problems with anxiety, sleeping or poor appetite
    •   generally low in sexual side-effects, but may cause weight gain.

    Noradrenalin Reuptake Inhibitors (NARIs)

    This class includes reboxetine. NARIs are:

    •   designed to act selectively on one type of brain chemical - noradrenalin
    •   less likely to cause sleepiness or drowsiness than some other antidepressants
    •   more likely to:
    •   make it difficult for people to sleep
    •   cause increased sweating after the initial doses
    •   cause sexual difficulties after the initial doses
    •   cause difficulty urinating after the initial doses
    •   cause increased heart rate after the initial doses.

    "Medication is not an instant fix. It takes time and often works alongside other strategies/treatments. In addition, you should be aware you will probably have side-effects, but they do ease over time and eventually, you will feel like you again." Gina, 38

    Things to note

    All of these drugs have been shown to have effect as antidepressants for more severe depression however their effectiveness differs from person to person.

    When symptoms are directly due to depression, the person is likely to begin to improve after 4-6 weeks of effective therapy. For example, although SSRIs commonly make sleep difficulties or insomnia worse initially, they are associated with improved sleep 4-6 weeks later.

    TCAs are commonly prescribed for their wide range of general benefits, but are also the most toxic antidepressants if taken in large quantities.

    SSRIs or clomipramie (TCA) would be the first choice if obsessive compulsive disorder symptoms were prominent.

    Monoamine Oxidase Inhibitors (MAOIs)

    This class includes tranylcypromine. MAOIs are prescribed only under exceptional circumstances as they require a special diet and have adverse effects.


    This class includes Mianserin. Tetracyclics:

    •   operate via noradrenaline and serotonin neurotransmitters systems
    •   include side-effects such as sedation and dizziness
    •   can cause a rare side-effect to arise, so occasional blood tests are necessary.

    What are the side effects?

    Antidepressants can make people feel better, but they won't change their personality or make them feel happy all the time. They will not improve unhappiness due to a predicament or an event. Like taking any other medication, some people will experience some sideeffects. Common side-effects, depending on which medication is taken, include nausea, headaches, anxiety, sweating, dizziness, agitation, weight gain, dry mouth and sexual difficulties (e.g. difficulty becoming/staying aroused).

    Some of the side-effects can be short-lived, but people who experience such symptoms should tell their doctor, as there may be ways of minimising them. The likelihood of a particular side-effect happening varies between individuals and medications.

    It is not uncommon for people with depression to have suicidal thoughts. Treating the depression effectively will reduce the likelihood of a person hurting him or herself. In the period of time between the person starting antidepressant medication and responding to treatment - which can be more than two weeks - the person should still be monitored by the doctor and his or her progress reviewed, as the risk of suicidal behaviour may even be slightly increased.

    How long are antidepressants usually needed?

    Like any medication, the length of time a person needs to take antidepressants for depends on how severe the illness is and how they respond to treatment. Some people only need to take them for a short time (usually 6-12 months) with psychological treatments and self-help techniques being sufficient in stopping its return. Others may need to take them over the long term to prevent recurrence.

    People often want to stop taking antidepressants quickly because they are concerned they are addictive. This may be because they confuse them with sedatives, a group of medications that are used to help a person feel relaxed and, in some cases, fall/stay asleep. Sedatives are designed to be used only for a short time. If used for long periods of time, sedatives may cause withdrawal insomnia and anxiety and be needed in higher doses in order for them to have the same effect. Sedatives may be craved and become addictive. This is not the case with antidepressants.

    Stopping some antidepressants quickly (e.g. some SSRIs and SNRIs) can lead to a discontinuation syndrome, which consists of flu-like symptoms. For many people, this will last for several days and can be avoided if the medications likely to do this are stopped gradually, on a doctor's recommendation and under supervision. However, in some cases these symptoms can last for weeks, months or even years. Sometimes discontinuation symptoms are severe, including irritability, agitation, dizziness and confusion.

    Stopping medication should only be done gradually, on a doctor's recommendation and under supervision.

    "No one treatment has been helpful by itself for me. It's been a combination of medication with talk therapy, as well as lifestyle changes such as getting regular exercise and modifying my diet (i.e. cutting down on alcohol and carbohydrate intake)." Greg, 42

    Everyone needs to find the treatment that's right for them. Just because a treatment has been shown to work scientifically, doesn't mean it will work equally well for every individual. Some people will have complications, side-effects or find that the treatment does not fit in with their lifestyle. It can take time, strength and patience to find a treatment that works.

    After seeking appropriate advice, the best approach is to try a treatment you're comfortable with and one that works for most people. If you do not recover quickly enough, or experience problems with the treatment, discuss this with your health professional and consider trying another.


    1 Reference: Beyond Blue (2011). Clinical practice guidelines for depression and related disorders - anxiety, bipolar disorder and puerperal psychosis - in the perinatal period. A guideline for primary care health professionals. Melbourne: Beyond Blue http:// health-news-evidence/2013/ssris-pregnancy

    2 NPS MedicineWise (2013). Is it safe to use SSRIs during pregnancy?. [online] Available at: au/publications/health-professional/health-newsevidence/2013/ssris-pregnancy [Accessed 22 Dec. 2014].

    This fact sheet was reviewed and updated in December 2016. Clinical information might change after this date. This fact sheet is not a substitution for medical advice from your doctor.

    Reference: Antidepressants Medication | Beyond Blue