How do antidepressants work?
Biological psychiatry assumes, without proof, that a number of neurotransmitters may influence your mood and emotions, such as serotonin and noradrenaline. Antidepressants act on these neurotransmitters.
The unproven hypothesis is that depressive complaints can arise when there is a shortage of these substances, or when they are not active enough between the brain cells. Antidepressants would then make up for possible shortages of serotonin or noradrenaline and keep the substances active as ‘messengers’ for longer.
The role of neurotransmitters in depression is unclear
It is important to realise that we have no idea whether neurotransmitters play a part in depression. The fact that antidepressants sometimes work through neurotransmitters does not mean that those neurotransmitters are the cause of depression. Chocolate makes some people happy, but that does not mean the brain has a happiness centre that runs on chocolate.
Every brain works differently
What the cause of the supposed shortage of serotonin or noradrenaline would be is not known. The idea of a ‘shortage’ is only a hypothesis, and every brain works differently. Because each type of antidepressant has a slightly different mechanism, it is hard to predict which antidepressant is effective for which person. Sometimes you have to try different medicines to find out which one works well enough for you.
Antidepressants do not work straight away
It can take a number of weeks before you notice an improvement. Do you still notice no difference after 4 to 6 weeks? Then it is good to contact your doctor. A change in your dose or a switch to another medicine may be a solution.
It can also happen that your complaints get somewhat worse when you have just started an antidepressant. After a week or two this should get better. If it does not, or if your complaints keep getting stronger, contact your prescriber in that case too.
Read more about how to use antidepressants and about antidepressants for anxiety.
Compare antidepressants
Antidepressants can have severe side effects. This differs per medicine. You cannot predict which medicine will work best for you; it is a matter of trying. The side effects of the different medicines are easier to predict, so it is best to choose on the basis of side effects.
With our tool Compare antidepressants you can set the side effects of the different antidepressants side by side.
How long do you have to take antidepressants?
It is important to be critical about how long you use antidepressants.
- First, many people use them without them really working, and you do not want that.
- Second, long-term use can lead in some people to a chemical increase in susceptibility to depression.
- Third, the longer you use them, the harder it can be to stop again, because of unpleasant withdrawal symptoms.
It is not fixed in advance how long you have to use antidepressants. This depends on a number of factors, for example whether you have had a depression before, how long you have had complaints and whether stressful circumstances continue.
In general you are advised to keep using the medication for at least six to nine months after you have recovered. This is to prevent complaints from coming back.
In some cases people take antidepressants for years. They are then used to prevent a new depression and mainly have a preventive effect. But it is important to keep asking whether they are still needed.
Evaluating your medication use with your doctor at regular intervals is important, also with long-term use.
Bipolarity and antidepressants
If someone is known to have manic depression, or bipolarity, an antidepressant may not be prescribed just like that. When an antidepressant is given without a mood stabiliser (such as lithium), this can trigger a manic episode.
Do you need help now?
PsychosisNet offers information. We do not offer a chat, a helpline or crisis support. If you or someone else is in immediate danger, call the emergency number in your country. If you are thinking about suicide, or you need to talk to someone now, see Need help now? for helplines by country.
Prof. dr. Jim van Os, Chair Division Neuroscience, Utrecht University Medical Centre. Jim works at the interface of ‘hard’ brain science, health services research, art and subjective experiences of people with ‘lived experience’ in mental healthcare.
Jim has been appearing on the Thomson-Reuter Web of Science list of ‘most influential scientific minds of our time’ since 2014. In 2014 he published his book ‘Beyond DSM-5‘, and in 2016 the book ‘Good Mental Health Care’. In 2026 he published 'Wat psychisch lijden is'.
Want to read more?
Blogs by Jim van Os can be read here
Did you know that PsychosisNet regularly posts new content?
Online tests
Compare antidepressants tool
Compare antipsychotics tool
Podcasts
Books
