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Key points

  • Antidepressants are usually prescribed for moderate or severe depression.
  • There are a number of different classes of antidepressant – most people take selective serotonin reuptake inhibitors (SSRIs).
  • It usually takes around two to four weeks before antidepressants start to have an effect.
  • All antidepressants have some side-effects.

Featured FAQ

Can I drink alcohol if I'm taking antidepressants?

Don't drink alcohol if you're taking antidepressants because alcohol can make your depression worse, slow down your reactions and make you drowsy. Also, some antidepressants can’t be taken with alcohol because together they can cause serious side-effects.

See all our FAQs on antidepressants

Antidepressants are used to treat depression and a number of other conditions. This factsheet provides information on some of the most common types of antidepressants.

Why would I take antidepressants?

Your doctor may prescribe antidepressants if you have depression. This is a condition in which you can have a low mood, a loss of interest in everyday activities, feelings of low self-worth, a lack of energy and poor concentration. If these symptoms last for a number of weeks then you may have depression.

Depression is classified as mild, moderate or severe depending on your symptoms and how much they interfere with your everyday life. You don’t usually need antidepressants for mild depression. Psychological therapies, or talking treatments, such as counselling or cognitive behavioural therapy (CBT), may be better for this type of depression. Antidepressants are usually prescribed for moderate or severe depression. However, you may also be offered psychological therapy alongside taking antidepressants.

Antidepressants can also be used in the treatment of other conditions, such as chronic (long-lasting) pain, anxiety and panic attacks, and obsessive compulsive disorder.

What are the main types of antidepressant?

There are a number of different classes of antidepressant. These include:

  • selective serotonin reuptake inhibitors (SSRIs)
  • tricyclics
  • monoamine-oxidase inhibitors (MAOIs)
  • serotonin and noradrenaline reuptake inhibitors (SNRIs)
  • noradrenaline and specific serotoninergic antidepressants (NaSSAs)

There are also other types of antidepressant medicines including agomelatine, a melatonin receptor agonist and a selective serotonin-receptor antagonist. All of these work well for moderate and severe depression but have different side-effects.

Your doctor will assess your symptoms and the potential side-effects and prescribe the most suitable medicine for you. Most people are prescribed an SSRI to start with since these generally have fewer side-effects and are the safest antidepressants. However, your doctor may prescribe other types of antidepressant if SSRIs haven’t worked or aren’t suitable for you.

How do antidepressants work?

The exact reasons why you may develop depression aren't fully understood at present. However, it's known that people with depression usually have reduced levels of certain brain chemicals called neurotransmitters, particularly two called noradrenaline and serotonin.

Neurotransmitters are released by nerve cells. They carry information across the tiny gap between one nerve cell and the next. Once they have done their job, neurotransmitters are re-absorbed into the nerve cell – this is called reuptake.

Antidepressants increase levels of serotonin and/or noradrenaline. The SNRIs, NaSSAs, tricyclics and MAOIs increase levels of both noradrenaline and serotonin, while SSRIs increase levels of serotonin only. These medicines work by either encouraging your nerve cells to make more of the neurotransmitters or by preventing their reuptake.

Agomelatine works on another chemical in your body called melatonin, as well as serotonin.

How to take antidepressants

Antidepressants are only available with a prescription from your doctor. This may be from your GP or a psychiatrist (a doctor who specialises in identifying and treating mental health conditions). Antidepressants come as tablets or capsules and sometimes in a liquid form. It’s important to take your medicine as prescribed by your doctor.

It usually takes around two weeks before antidepressants start to have an effect and it can take up to six weeks for them to have a full effect. You will need to visit your doctor regularly when you first start to take antidepressants to see how well they are working. If they aren’t working well after four to six weeks, your doctor may consider increasing the dose or may prescribe you a different antidepressant to see if it works better for you.

If you find an antidepressant that works for you, you will probably need to carry on taking it for at least six months, even once your symptoms have gone away. This can help prevent depression coming back. You may need to take antidepressants for two years or more if you get repeated bouts of depression.

Always ask your doctor for advice and read the patient information leaflet that comes with your medicine.

Special care

If you have heart problems, or if you're pregnant or breastfeeding, tell your doctor before you take an antidepressant. Certain antidepressants are safer for people who have heart problems, or for women who are pregnant or breastfeeding.

Side-effects of antidepressants

Side-effects are the unwanted effects of taking a medicine. If you have side-effects, it’s important to talk to your GP or the healthcare professional who prescribed your medicine before you stop taking it.

All antidepressants have some side-effects. Some side-effects, such as feeling sick and anxiety, are more common in the first week or two of treatment and often get better. Taking certain antidepressants can slow down your reaction speeds and affect activities that require concentration, such as driving. Ask your doctor whether it’s safe for you to drive while taking your medicine. All antidepressants can affect your sex life – talk to your GP if you’re worried about this.

Below we describe common side-effects for some of the main classes of antidepressants. This section doesn’t include every possible side-effect of antidepressants. Please read the patient information leaflet that comes with your medicine for more information and if you're worried about possible side-effects, ask your doctor for advice.

Selective serotonin reuptake inhibitors

Although SSRIs have some side-effects, they are generally less troublesome than those of other antidepressants and so are prescribed most often. In particular, they are less likely to make you feel drowsy or give you a dry mouth. Side-effects of SSRIs include:

  • feeling sick or vomiting
  • indigestion
  • diarrhoea or constipation
  • weight loss
  • anxiety
  • headaches
  • skin reactions, such as a rash
  • shaking
  • dizziness
  • dry mouth
  • fits

Rarely, some people experience suicidal thoughts after starting SSRI’s. If this happens to you, you must seek urgent medical attention.

Side-effects of SNRIs and NaSSAs tend to be similar to those of SSRIs.

Tricyclic antidepressants

Common side-effects of tricyclics include:

  • difficulty sleeping
  • drowsiness or tiredness
  • dizziness
  • anxiety
  • confusion
  • irritability
  • dry mouth
  • blurred vision
  • constipation
  • difficulty passing urine
  • weight gain (although some people lose weight)

Some of these side-effects settle down with time, so carry on taking your medicine if you get these symptoms. Don’t stop taking your antidepressants without speaking to your doctor first.

Rarely, tricyclics may also cause arrhythmias (heart palpitations) and fits. Because of this, they are used less often than SSRIs.

Monoamine-oxidase inhibitors

MAOI antidepressants can interact with other medicines and some common foods, and increase the risk of side-effects. Because of this, MAOIs aren't prescribed very often. If you’re taking a MAOI antidepressant, your doctor will give you a list of foods that you shouldn’t eat.

Side-effects of MAOIs can include:

  • dizziness
  • low blood pressure
  • headaches
  • insomnia
  • constipation
  • dry mouth
  • anxiety

Discontinuation symptoms

Antidepressants aren't addictive but you may get withdrawal symptoms (often referred to as discontinuation syndrome) if you stop taking them suddenly. Symptoms of sudden withdrawal include:

  • feeling sick
  • trouble sleeping
  • feeling irritable
  • diarrhoea
  • headaches
  • dizziness
  • chills or tingling or prickly skin
  • anxiety and panic

If you want to stop taking antidepressants, talk to your doctor first. He or she may suggest that you reduce the dose slowly, over a period of weeks, as this can help to prevent withdrawal symptoms.

Interactions of antidepressants with other medicines

Antidepressants can interact with some over-the-counter medicines. For example, if you take SSRIs with painkillers, such as aspirin or ibuprofen, it can increase the risk of bleeding in your stomach. Always ask your GP for advice and read the patient information leaflet that comes with your medicine.

Herbal remedies contain active ingredients and may interact with other medicines or cause side-effects. Don’t start a herbal remedy without speaking to your doctor or pharmacist first. St John's wort, for example, which is sold as a herbal antidepressant, can be harmful if you take it with prescribed antidepressants and it can interact with other medicines, such as the contraceptive pill.

Names of common antidepressants

Examples of the main types of antidepressants are shown in the table below.

Each medicine has a generic name, which is its official medical name. Many medicines also have at least one brand name, which is the trade name. Generic names are written in lower case and brand names start with a capital letter.

If you're not sure which medicine you have been prescribed, ask your pharmacist for advice.

Generic name Brand name
Selective serotonin re-uptake inhibitors
citalopram Cipramil
escitalopram Cipralex
fluoxetine Prozac
fluvoxamine Faverin
paroxetine Seroxat
sertraline Lustral
Serotonin and noradrenaline reuptake inhibitors
duloxetine Cymbalta, Yentreve
reboxetine Edronax
venlafaxine Efexor
Noradrenaline and specific serotoninergic antidepressants
mirtazapine Zispin
Tricyclic antidepressants
amitriptyline Triptafen
clomipramine Anafranil
dosulepin Prothiaden
doxepin Sinepin
nortriptyline Allegron
trimipramine Surmontil
Monoamine-oxidase inhibitors
phenelzine Nardil


Produced by Rachael Mayfield-Blake, Bupa Heath Information Team, June 2013.

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For answers to frequently asked questions on this topic, see FAQs.

For sources and links to further information, see Resources.

  • This information was published by Bupa's Health Information Team and is based on reputable sources of medical evidence. It has been reviewed by appropriate medical or clinical professionals. Photos are only for illustrative purposes and do not reflect every presentation of a condition. The content is intended only for general information and does not replace the need for personal advice from a qualified health professional. For more details on how we produce our content and its sources, visit the about our health information page.

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