Antidepressants are a group of medications that are used to treat depression.
Antidepressants are medicines used to treat depression, anxiety and related conditions, such as eating disorders, obsessive-compulsive disorder and post-traumatic stress disorder. Antidepressants are effective for moderate to severe depression, but not very effective for mild depression. Psychological treatments such as cognitive behaviour therapy (CBT) and talking therapy work better for mild depression. To improve the symptoms of depression, the effectiveness of antidepressants can be improved when used together with psychological therapies and lifestyle changes. Read more about depression.
Which antidepressants are available in New Zealand?
There is a variety of groups or classes of antidepressants available in New Zealand. Each class works on different chemicals in your brain and may cause different side effects.
|Class of antidepressant||Examples|
|Selective serotonin reuptake inhibitors (SSRIs)|
|Serotonin and noradrenaline reuptake inhibitors (SNRIs)||
How do antidepressants work?
We don't know for certain, but we think that antidepressants work by increasing the activity of certain chemicals working in our brains called neurotransmitters. They pass signals from one brain cell to another. The chemicals most involved in depression are thought to be serotonin and noradrenaline. While depression is not simply a deficiency of these chemicals (see depression and severe depression), we do know that these medications help to relieve symptoms of depression and anxiety in approximately 50 to 70% of people who try them. Some people will respond to one antidepressant better than another so changes may be needed.
Selective serotonin reuptake inhibitors (SSRIs) are the most frequently prescribed antidepressants. SSRIs are called selective because they only affect serotonin.
What are the considerations when choosing an antidepressant?
The exact antidepressant medication you are prescribed will depend on the severity and type of your illness, if you have other medical conditions, if you are taking other medication, your response to antidepressant medication in the past and possible side effects.
When deciding on the best medication for you, it's important to discuss with your healthcare provider the possible side effects of the medication and how they are likely to impact on your lifestyle. The following resources provide more information about what to think about when choosing antidepressant medication and may be useful for discussions with your healthcare provider. Be aware these are from other countries and may contain information that differs from New Zealand recommendations.
- Antidepressants: Selecting one that's right for you
- Depression: Should I take an antidepressant?
- Depression: treatment options Option Grid
How long will I need to take antidepressants for?
This will depend on a number of factors and is best discussed with your doctor. It is common to be on antidepressants for at least 6 to 12 months for a first episode of moderate to severe depression needing medication.
- If you have troublesome side effects or little improvement in your symptoms after 6 weeks, talk to your doctor about changing the dose, trying a different antidepressant (switching), or adding a second antidepressant or another medication (augmentation). A medication combination may work better for you than a single antidepressant.
- If this is not your first experience of depression, your doctor may prescribe longer treatment. You may be able to stop these medicines after a while. They are not addictive.
- If you plan to stop taking antidepressants, talk with your doctor first about how to do it safely. It's best to slowly decrease your dose. Suddenly stopping can cause side effects. It may also cause your depression to come back or get worse.
What about the side effects of antidepressants?
Different antidepressants have different side effects and risks.
- A few people experience agitation, nausea, insomnia, headaches and sexual problems when taking SSRIs. Talk to your healthcare provider if these things happen to you. Read more about SSRIs.
- SNRIs such as venlafaxine have similar side effects to the SSRIs, and may also cause loss of appetite, sweating and rashes.
- Common side effects with mirtazapine includes weight gain and drowsiness.
- Side effects are more common with TCAs, and these can include drowsiness, blurred vision, weight gain, constipation and difficulty urinating (peeing), a dry mouth and sexual problems.
Let your doctor know if you experience any side effects while on antidepressants, so they can adjust the dose or try a different medication.
The use of antidepressants has been linked with an increase in suicidal thoughts and behaviour. Children, teenagers, young adults and people with a history of suicidal behaviour are particularly at risk. This is most likely during the first few weeks of starting an antidepressant or if the dose is changed. It is important to look for signs of suicidal behaviour such as agitation or agression and ask about suicidal thoughts, self-harm, worsening of low mood. If you notice any of these signs, contact your doctor immediately.
It is ok and important to ask about suicidal thoughts and this will not increase risk.
If you suspect you or someone you know might be suffering from depression, read more on our depression section or visit thelowdown.co.nz or depression.org.nz for helpful information, including a self-test.
The following links provide further information on antidepressants. Be aware websites from other countries may contain information that differs from New Zealand recommendations.
Tricyclic antidepressants Patient Info, UK
Antidepressants Patient Info, UK
Are you taking medicines for epilepsy, mood or pain? ACC, New Zealand
- The role of medicines in the management of depression in primary care BPAC, NZ 2017
- Antidepressant drugs New Zealand Formulary, NZ
- Antidepressant drugs New Zealand Formulary for Children, NZ
- Antidepressants Royal College of Psychiatrists, UK
- Antidepressants Centre for Addiction and Mental Health, Canada
- Royal Australian and New Zealand College of Psychiatrists clinical practice guidelines for mood disorders. Australian and New Zealand Journal of Psychiatry, 2015