This information is for anyone who wants to know more about antidepressants. It describes how they work, why they are prescribed, their effects and side-effects, and alternative treatments.


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Antidepressants are medications that can help relieve the symptoms of depression and are used in the treatment of some other conditions. They were first developed in the 1950s and have been used regularly since then. There are almost thirty different kinds of antidepressants and five main categories:

  • SSRIs (Selective Serotonin Reuptake Inhibitors)
  • SNRIs (Serotonin and Noradrenaline Reuptake Inhibitors)
  • NASSAs (Noradrenaline and Specific Serotoninergic Antidepressants)
  • Tricyclics
  • MAOIs (Monoamine Oxidase Inhibitors).

This resource focuses on how antidepressants are used for treating the symptoms of depression.

How do they work?

We don't know for certain, but antidepressants do affect the activity of certain chemicals in our brains called neurotransmitters. These pass signals from one brain cell to another. The neurotransmitters most affected by antidepressants are serotonin and noradrenaline.

Antidepressants should not usually be prescribed for mild depression but are recommended, usually in combination with psychotherapies, for adults with moderate to severe depressive illness.

They should not normally be used for children and adolescents, unless their depression has not responded to other treatments or is particularly severe.

Antidepressants may also be prescribed for some other conditions:

Your doctor should explain why they are suggesting an antidepressant for you, and should go through the potential benefits and risks of taking an antidepressant.

Overall, research shows antidepressants help to reduce the symptoms of moderate and severe depression in adults. But different people have very different experiences with these medications.

While some people will get better without them, generally people see an improvement in their symptoms and quality of life after using antidepressants, particularly when their depression is more severe. Some patients report mixed experiences of feeling the benefit of functioning better but also of having side effects. Others find that these medications just don’t work, or have very unpleasant side effects.

If your doctor does prescribe an antidepressant, they will still need to see you regularly to monitor how you are, whether you are getting side effects, and whether you need to carry on taking the antidepressant.

Antidepressants don't necessarily treat the underlying cause of the depression, or take it away completely – but they can help to control the symptoms. That is why they are often used together with psychotherapies.

The older types of antidepressant (tricyclics) are just as effective as the newer ones (SSRIs) but, on the whole, SSRIs have fewer side-effects and are not so dangerous if someone takes an overdose of them.

Yes – your doctor should discuss these with you before you agree to starting using them. You should tell your doctor about any medical conditions you have or have had in the past – this can affect type of antidepressant they recommend for you.

Here are some common side effects you might experience with the different types of antidepressant.


It is normal to experience some unpleasant side effects when you start taking SSRIs and SNRIs. The leaflets that come with the medication will have full details of these, but they may include:

  • feeling agitated, shaky or anxious (this is often why people stop taking their antidepressant, especially if they have not been warned about it – but it usually passes off a few days after starting the antidepressant)
  • feeling and being sick
  • indigestion and stomach aches
  • diarrhoea or constipation
  • loss of appetite
  • dizziness
  • not sleeping well (insomnia), or feeling very sleepy
  • headaches
  • low sex drive
  • difficulties achieving orgasm during sex or masturbation
  • in men, difficulties obtaining or maintaining an erection (erectile dysfunction).

While the list of side effects looks worrying, they will be mild for most people and will usually wear off over a couple of weeks as your body gets used to the medication.

You should talk to your doctor if you are worried about any of the side effects, if they persist longer than a few weeks or if they are or become unbearable.


The side-effects for NASSAs are very similar to SSRIs. They can make you feel drowsy, and cause weight gain, but they cause fewer sexual problems. 


These can often cause:

  • dry mouth
  • slight blurring of vision
  • constipation
  • problems passing urine
  • drowsiness
  • dizziness
  • weight gain
  • excessive sweating (especially at night)
  • heart rhythm problems, such as noticeable palpitations or a fast heartbeat (tachycardia).

Like with SSRIs/SNRIs, these side effects will usually be mild and wear off over a couple of weeks. You should talk to your doctor if you have any concerns or if the symptoms are unbearable.


This type of antidepressant is rarely prescribed these days, and only usually by a specialist doctor, as they have potentially more serious side effects.


For a full patient information, including side effects, please visit the Electronic Medicines Compendium (EMC) and type in the name of the medicine in the search box at the top of the page.

Some antidepressants make you sleepy and slow down your reactions, so cannot be taken if you are driving or operating machinery. You should check with your doctor and look at the leaflet that comes with the medication to be sure.

Stopping an antidepressant can give you unpleasant withdrawal symptoms – which stop if you start taking it again. It can certainly feel as though you are addicted to the antidepressant – but it’s not quite the same as being addicted.

You don’t get the craving for constantly having to increase the dose that you do with substances like alcohol, nicotine or benzodiazepines. But it can still be hard to stop taking an antidepressant.

Here you can find a list of the common antidepressants, their trade names in the UK, and their type.

MedicationTrade nameGroup
Amitriptyline Tryptizol Tricyclic
Clomipramine Anafranil Tricyclic
Citalopram Cipramil SSRI
Dosulepin Prothiaden Tricyclic
Doxepin Sinequan Tricyclic
Duloxetine Cymbalta, Yentreve SNRI
Fluoxetine Prozac SSRI
Imipramine Tofranil Tricyclic
Lofepramine Gamanil Tricyclic
Mirtazapine Zispin NaSSA
Moclobemide Manerix MAOI
Nortriptyline Allegron Tricyclic
Paroxetine Seroxat SSRI
Phenelzine Nardil MAOI
Reboxetine Edronax SNRI
Sertraline Lustral SSRI
Tranylcypromine Parnate MAOI
Trazodone Molipaxin Tricyclic-related
Venlafaxine Efexor SNRI

We have developed a separate information resource on stopping antidepressants, that looks at this area in detail and provides advice on how to gradually stop their use.

There is some evidence of increased suicidal thoughts (although not actual suicidal acts) and other side-effects in young people taking antidepressants. Their use among children and adolescents (under the age of 18) is only recommended when they have moderate to severe depression that has not got better with other treatment, such as psychotherapies. There may, however, be instances when they are used straight away for more severe depression under the supervision of specialist psychiatrist.

There is no clear evidence of an increased risk of self-harm and suicidal thoughts in adults of 18 years or over. But, people mature at different times, so any young adult taking an antidepressant should be particularly closely monitored.

It is always best to take as little medication as possible while you are pregnant – and antidepressants are not usually recommended for most pregnant women. However, if you are already taking antidepressants, or feeling unwell to the extent that you may need to do so, you should discuss how this might affect your baby with your doctor.

Antidepressants are also not usually recommended if you're breastfeeding. However, there may be times where the benefits of breastfeeding for your baby, and the benefit of antidepressant treatment for you, need to be weighed up against the risks of taking an antidepressant. Again, it’s really important to discuss this with your doctor.

For further information, see our leaflet on mental health in pregnancy.

  • Keep in touch with your doctor when you start treatment. They will monitor you for side effects and how you feel. They may advise you to change the dose. It doesn’t help to increase the dose above the recommended levels. If you are being given the drug for anxiety, your doctor may suggest that you start on a very low dose for the first few weeks.
  • Try not to be put off if you get some side effects. Many of them wear off in a week or so. Don't stop your antidepressant unless the side effects are unbearable. If they are, get an urgent appointment to see your doctor. If you feel worse it is important to tell your doctor so that they can decide if that antidepressant is right for you. Your doctor will also want to know if you have noticed increased feelings of restlessness or agitation.
  • Take them as prescribed by your doctor – if you don't, they won't work.
  • Wait for them to work. Most people find that they take 1-2 weeks to start working and maybe up to 6 weeks to give their full effect.
  • Persevere – stopping too early is the most common reason for people not getting better and for the depression to return.
  • Try not to drink alcohol. Alcohol on its own can make any depression worse, but it can also make you slow and drowsy if you are taking antidepressants.
  • Keep them out of the reach of children.
  • If you are struggling, and have thought about taking an overdose, tell your doctor as soon as possible – and give your antidepressants to someone else to keep for you.
  • Tell your doctor about any major changes in how you feel when the dose of antidepressant is changed.

How long you take an antidepressant for depends on why you were prescribed them and whether you have had to take them before. The NICE guidelines advise that it is best to continue to take antidepressants for at least six months after you start to feel better. If you stop the medication before then, the symptoms of depression are more likely to come back. It is worthwhile thinking about what might have made you vulnerable, or might have helped to trigger your depression. There may be ways of making this less likely to happen again.

If you have had two or more periods of depression then you should carry on taking the antidepressant for at least two years.

Some people have severe depression over and over again. Even when they have got better, they may need to take antidepressants for several years to stop their depression coming back. This is particularly important in older people, who are more likely to have several periods of depression.

For some people, other drugs such as lithium may be recommended in addition to antidepressants. Psychotherapies can also be helpful, in addition to an antidepressant.

It's difficult to say – so much depends on why they have been prescribed, on how bad your depression is and on how long you've had it for. Sometimes depression gets better without any treatment or with other treatments, such as psychotherapies.

Your doctor should talk this through with you before they are prescribed so that you fully understand the benefits and risks of taking and not taking antidepressants.

When you have mild depression, you will normally be recommended a psychotherapy. If your symptoms are or become more severe, it is normal to use antidepressants and psychotherapies together.


There are a number of helpful talking treatments for depression, often recommended as a first option, or used in combination with antidepressants. Counselling can be useful in mild depression. Problem solving techniques can help where the depression has been caused by difficulties in life. Cognitive Behavioural Therapy helps you to look at the way you think about yourself, the world and other people. For information about these and other forms of psychotherapy, see our leaflets on psychotherapies and cognitive behavioural therapy (CBT).

Herbal remedies

There is also a herbal remedy for depression called Hypericum – made from a herb, St Johns Wort – that may benefit people with mild or moderate depression and is available without prescription. Because it is a herbal treatment, it is less well researched and there may be variations in the preparations on sale. Another problem is that it can interfere with other medicines like the contraceptive pill. If you are taking other medication, you should discuss it with your doctor.

General wellbeing

It is important to think about your general wellbeing – and to find ways of making yourself feel better, so you are less likely to become depressed again. These can include finding someone you can talk to, keeping physically active, drinking less alcohol, eating well, using self-help techniques to help you relax and finding ways to solve the problems that have brought the depression on. For some tips on self-help, see our leaflet on depression.


You may find that you get depressed every winter but cheer up when the days become longer. This is called seasonal affective disorder (SAD). If so, you may find a light box helpful – this is a source of bright light which you have on for a certain time each day and which can make up for the lack of light in the winter – however, it isn’t clear how well this works so you should talk to your doctor if you are concerned about feeling this way.

If you have any further questions about antidepressants which haven't been covered in this leaflet, take a look at the other sources of information here and speak with your doctor. It's also good to talk things over with your family or friends.

  • Electronic Medicines Compendium – Summaries of Drugs and Patient Information Leaflets (PILs). Information on thousands of licensed medicines available in the UK. Continuously updated.
  • NHS advice on antidepressants – The NHS guide to the use of antidepressants, covering cautions, dosage, side effects and alternatives.
  • Mind – Antidepressants – Information from the mental health charity, Mind, explaining what antidepressants are, how they work, possible side effects and information about withdrawal.
  • Rethink Mental Illness – Antidepressants – Information from the mental health charity, Rethink Mental Illness, about antidepressants.

Produced by the RCPsych Public Engagement Editorial Board.

Series Editor: Dr Phil Timms

Series Manager: Thomas Kennedy

Published: Sep 2020

Review due: Sep 2023

© Royal College of Psychiatrists