Introduction

Antidepressants
Antidepressants

Antidepressents are a type of medication used to treat Clinical depression.

They can also be used to treat a number of other conditions including:

Antidepressants are also sometimes used to treat people with long-term (chronic) pain.

Read more about what antidepressants are used for.

How antidepressants work

It's not known exactly how antidepressants work.

It is thought they work by increasing the levels of chemicals in the brain called neurotransmitters. Certain neurotransmitters, such as serotonin and noradrenaline, are linked to mood and emotion.

Neurotransmitters may also affect pain signals sent by nerves, which may explain why some antidepressants can help relieve long-term pain.

While antidepressants can treat the symptoms of depression, they do not always address its causes. This is why they are usually used in combination with therapy to treat more severe depression or other mental health conditions.

How effective are antidepressants?

Research suggests that antidepressants can be helpful for people with moderate or severe depression.

Studies have shown that they're better than placebo ("dummy medicine") for people with these conditions.

They're not usually recommended for mild depression, unless other treatments like therapy haven't helped.

The Royal College of Psychiatrists estimates that 50-65% of people treated with an antidepressant for depression will see an improvement, compared to 25-30% of those taking a placebo.

Doses and duration of treatment

Antidepressants are usually taken in tablet form. When they are prescribed, you will start on the lowest possible dose thought necessary to improve your symptoms.

Antidepressants usually need to be taken for 1 or 2 weeks (without missing a dose) before the benefit to be felt. It's important not to stop taking them if you get some mild side effects early on, as these effects usually wear off quickly.

If you take an antidepressant for four weeks without feeling any benefit, speak to your GP or mental health specialist. They may recommend increasing your dose or trying an alternative medicine.

A course of treatment usually lasts at least six months. Some people with recurrent depression may be advised to take them indefinitely.

Read more about antidepressant doses.

Side effects

Different antidepressants can have a range of different side effects. Always check the information leaflet that comes with your medicine to see what the possible side effects are.

The most common side effects of antidepressants are usually mild. Side effects should improve within a few days or weeks of treatment, as the body gets used to the medication.

Read more about the possible side effects of antidepressants and cautions and interactions of antidepressants.

There are several different types of antidepressants.

Selective serotonin reuptake inhibitors (SSRIs)

SSRIs are the most widely prescribed type of antidepressants. They're usually preferred over other antidepressants, as they cause fewer side effects. An overdose is also less likely to be serious.

Fluoxetine is probably the best known SSRI (sold under the brand name Prozac). Other SSRIs include citalopram (Cipramil), paroxetine (Seroxat) and sertraline (Lustral).

Serotonin-norepinephrine reuptake inhibitors (SNRIs)

SNRIs are similar to SSRIs. They were designed to be a more effective antidepressant than SSRIs. However, the evidence that SNRIs are more effective in treating depression is uncertain. It seems some people respond better to SSRIs, while others respond better to SNRIs.

Examples of SNRIs include duloxetine (Cymbalta and Yentreve) and venlafaxine (Efexor).

Noradrenaline and specific serotonergic antidepressants (NASSAs)

NASSAs may be effective for some people who are unable to take SSRIs. The side effects of NASSAs are similar to those of SSRIs, but they're thought to cause fewer sexual problems. However, they may also cause more drowsiness at first.

The main NASSA prescribed in the UK is mirtazapine (Zispin).

Tricyclic antidepressants (TCAs) 

TCAs are an older type of antidepressants. They are no longer usually recommended as a first-line treatment for depression because they can be more dangerous if an overdose is taken. They also cause more unpleasant side effects than SSRIs and SNRIs.

Exceptions are sometimes made in people with severe depression that fails to respond to other treatments. TCAs may also be recommended for other mental health conditions such as obsessive compulsive disorder and bipolar disorder.

Examples of TCAs include amitriptyline (Tryptizol), clomipramine (Anafranil), imipramine (Tofranil), lofepramine (Gamanil), nortriptyline (Allegron)

Some types of TCAs, such as amitriptyline, can also be used to treat chronic nerve pain.

Monoamine oxidase inhibitors (MAOIs)

MAOIs are an older type of antidepressant that are rarely used nowadays.

They can cause potentially serious side effects so should only be prescribed by a specialist doctor.

Examples of MAOIs include tranylcypromine, phenelzine and isocarboxazid.

Other treatments for depression include talking therapies such as cognitive behavioural therapy (CBT).

Increasingly, people with moderate to severe depression are treated using a combination of antidepressants and CBT. Antidepressants work quickly in reducing symptoms, whereas CBT takes time to deal with causes of depression and ways of overcoming it.

Regular exercise has also been shown to be useful for those with mild depression.

Read more about alternatives to antidepressants.

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Uses

The main use for antidepressants is treating clinical depression in adults. They're also used for other mental health conditions and treatment of long-term pain.

In most cases, adults with moderate to severe depression are given antidepressants as a first form of treatment. They're often prescribed along with a talking therapy such as cognitive behavioural therapy (CBT). CBT is a type of therapy that uses a problem-solving approach to help improve thought, mood and behaviour.

Antidepressants aren't always recommended for treating mild depression because research has found limited effectiveness.

However, antidepressants are sometimes prescribed for a few months for mild depression to see if you experience any improvement in your symptoms. If you don’t see any benefits in this time, the medicine will be slowly withdrawn.

Initially, a type of antidepressant called a selective serotonin reuptake inhibitor (SSRI) is usually prescribed. If your symptoms haven't improved after about four weeks, an alternative antidepressant may be recommended or your dose may be increased.

Many antidepressants can be prescribed by your GP, but some types can only be used under the supervision of a mental health professional. If the depression doesn't respond to antidepressant alone, other treatments, such as CBT, may also be used to help achieve better results. They may also give higher doses of the medication.

Children and young people

Children and young people with moderate to severe depression should first be offered a course of psychotherapy that lasts for at least three months.

In some cases, an SSRI called fluoxetine may be offered in combination with psychotherapy to treat moderate to severe depression in young people aged 12-18.

Other mental health conditions

Antidepressants can also be used to help treat other mental health conditions, including:

As with depression, SSRIs are usually the first choice of treatment for these conditions. If SSRIs prove ineffective, another type of antidepressant can be used.

Long-term pain

Even though a type of antidepressant called tricyclic antidepressants (TCAs) weren't originally designed to be painkillers, there's evidence to suggest they're effective in treating chronic (long-term) nerve pain in some people.

Chronic nerve pain, also known as neuropathic pain, is caused by nerve damage or other problems with the nerves, and is often unresponsive to regular painkillers, such as paracetamol.

Amitriptyline is a TCA that's usually used to treat neuropathic pain. Conditions that may benefit from treatment with amitriptyline include:

Antidepressants have also been used to treat cases of chronic pain that don't involve nerves (non-neuropathic pain). However, they're thought to be less effective for this purpose. As well as TCAs, SSRIs and serotonin-noradrenaline reuptake inhibitors (SNRIs) can also be used to treat chronic non-neuropathic pain.

Conditions that cause non-neuropathic pain which may benefit from treatment with antidepressants include fibromyalgia, chronic back pain and chronic neck pain.

Bedwetting in children

TCAs are sometimes used to treat bedwetting in children, as they can help relax the muscles of the bladder. This increases bladder capacity and reduces the urge to urinate.

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Cautions

There are several important things to consider when taking antidepressants. You should discuss these with your GP or mental health professional.

Interactions with other medications

Antidepressants can react unpredictably with other medications, including over-the-counter medications such as ibuprofen. Always read the patient information leaflet that comes with your medicine to see if there are any medicines you should avoid.

If in doubt, your pharmacist or GP should be able to advise you.

Pregnancy

As a precaution, antidepressants aren't usually recommended for most pregnant women, especially during the early stages of a pregnancy.

This is because they might be dangerous for your baby.

But exceptions can be made if the risks posed by depression (or other mental health conditions) outweigh any potential risks of treatment.

If you're pregnant and depressed, you should discuss the pros and cons of antidepressants with the doctor in charge of your care.

Breastfeeding

As a precaution, the use of antidepressants if you're breastfeeding isn't usually recommended.

However, there are circumstances when both the benefits of treatment for depression (or other mental health conditions) and the benefits of breastfeeding your baby outweigh the potential risks.

Speak to your doctor for advice.

Children and young people

The use of antidepressants isn't usually recommended in children and young people under the age of 18. This is because there's evidence that, in rare cases, they can trigger thoughts about suicide and acts of self-harm in this age group.

Concerns have also been raised that their use could affect the development of the brain in children and young people.

An exception can usually only be made if the following points are met:

  • the person being treated has failed to respond to talking therapies such as cognitive behavioural therapy, and
  • the person being treated will continue to receive talking therapies in combination with antidepressants, and
  • the treatment is supervised by a psychiatrist (a doctor who specialises in treating mental health conditions)

Alcohol

You should be wary of drinking alcohol if you're taking antidepressants, as alcohol is itself a depressant and drinking alcohol can make your symptoms worse.

If you drink alcohol while taking types of antidepressants called tricyclic antidepressants (TCAs) or monoamine oxidase inhibitors (MAOIs), you may become drowsy and dizzy.

You're less likely to experience unpleasant or unpredictable effects if you drink alcohol while taking an SSRI or a serotonin-noradrenaline reuptake inhibitor (SNRI) antidepressant, but avoiding alcohol is often still recommended in these cases.

Illegal drugs

The use of illegal drugs isn't recommended if you're taking antidepressants, particularly if you've been prescribed a TCA. This is because they can cause unpredictable and unpleasant effects.

In particular, you should avoid taking:

  • cannabis – smoking cannabis while taking a TCA can make you feel very ill
  • amphetamines (speed)
  • cocaine
  • heroin
  • ketamine

As with alcohol, illegal drugs can make symptoms of depression or other mental health conditions worse.

Other antidepressants

You should never take two different types of antidepressants, such as an SSRI and a TCA, unless advised by a doctor. This is because taking certain combinations of antidepressants can make you feel very ill and can be life-threatening.

If a decision is taken to switch you from one type to another, the dosage of the first antidepressant will usually be gradually reduced before the second is administered.

St John’s Wort

St John’s Wort is a popular herbal remedy promoted for the treatment of depression.

While there's evidence of its effectiveness, many experts advise against its use, because the amount of active ingredient varies among individual brands and batches, making the effects unpredictable.

Taking St John's Wort with other medications, such as anticonvulsants, anticoagulants, antidepressants and the contraceptive pill, can also cause serious health problems.

You shouldn't take St John's Wort if you're pregnant or breastfeeding, as it's unclear whether it's safe.

Driving and operating machinery

Some antidepressants can cause dizziness, drowsiness and blurred vision, particularly when you first start taking them.

If you do experience these problems, you should avoid driving or using tools and machinery.

Cautions for specific antidepressants:

SSRIs

SSRIs may not be suitable if you have:

  • bipolar disorder and you're in a manic phase (a period where you're extremely excitable), although they can be useful for depressive phases
  • a bleeding disorder, or if you're taking medicines that make it more likely you may bleed (such as warfarin)
  • type 1 diabetes and type 2 diabetes
  • epilepsy – SSRIs should only be taken if your epilepsy is well controlled, and the medicine should be stopped if your epilepsy gets worse
  • kidney disease

SNRIs

SNRIs may not be suitable if you have a history of heart disease or you have poorly controlled high blood pressure.

TCAs

TCAs may not be suitable if you have:

  • a history of heart disease
  • recently had a heart attack
  • liver disease
  • an inherited blood disorder called porphyria
  • bipolar disorder
  • schizophrenia
  • a growth on your adrenal glands that is causing high blood pressure (pheochromocytoma)
  • an enlarged prostate gland
  • narrow angle glaucoma – increased pressure in the eye
  • epilepsy
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Dosage

When prescribing antidepressants, your GP usually selects the lowest possible dose thought necessary to improve your symptoms.

This approach is intended to reduce the risk of side effects. If this dose doesn't work, it can be gradually increased.

Antidepressants are usually taken in tablet form. Depending on the type of antidepressant prescribed and the severity of your depression, you'll usually have to take one to three tablets a day.

It usually takes around seven days before you begin to notice the effects of antidepressants. Contact your doctor if you haven't noticed any improvement after four weeks, as they may recommend increasing your dose or trying an alternative antidepressant.

It's usually recommended that a course of antidepressants lasts at least six months, to prevent your condition recurring when you stop. Some people with recurrent illness are advised to carry on taking medicine indefinitely.

The recommended course of treatment largely depends on weighing up the benefits of the medication against the side effects. If your illness is severe and the medication is effective, treatment will often be continued. If your illness is mild and the medication doesn’t help and causes side effects, continued treatment won't be recommended.

Missed or extra doses

It's important not to miss any of your doses, as this could make your treatment less effective.

If you do miss one of your doses, take it as soon as you remember, unless it's almost time to take your next dose. In this case, you should just skip the missed dose. Don't take a double dose to "make up" for the one you missed.

If you take more tablets than prescribed, contact your GP as soon as possible for advice. If this isn't possible, contact your local out of hours service, or call NHS Direct Wales 0n 0845 46 47, or 111 if available in your area. Taking a double dose is unlikely to be harmful, but you should only do so if advised by a medical professional.

Stopping antidepressants

You shouldn't suddenly stop taking antidepressants, even if you feel better. Stopping suddenly can lead to withdrawal symptoms, such as:

  • stomach upsets
  • flu-like symptoms
  • anxiety
  • dizziness
  • sensations in the body that feel like electric shocks
  • seizures (fits)

Coming off antidepressants too soon can cause your condition to return. Stopping before you have been taking them for four weeks may mean the medicine hasn't had a chance to take effect.

If your GP or mental health specialist decides to stop your course of antidepressants, they'll reduce the dose gradually over a few weeks.

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Side effects

The side effects of antidepressants can cause problems at first, but then generally improve with time.

It's important to continue treatment, even if you're affected by side effects, as it will take several weeks before you begin to benefit from treatment. With time, you should find that the benefits of treatment outweigh any problems from side effects.

During the first few months of treatment, you'll usually see your doctor or a specialist nurse at least once every two to four weeks to see how well the medicine is working.

For more information about your specific medicine, see the patient information leaflet that comes with it.

SSRIs and SNRIs

Common side effects of selective serotonin reuptake inhibitors (SSRIs) and serotonin-noradrenaline reuptake inhibitors (SNRIs) can include:

These side effects should improve within a few weeks, although some can occasionally persist.

Tricyclic antidepressants (TCAs)

Common side effects of TCAs can include:

The side effects should ease after a couple of weeks as your body begins to get used to the medication.

Potential health risks

Serotonin syndrome

Serotonin syndrome is an uncommon, but potentially serious, set of side effects linked to SSRIs and SNRIs.

Serotonin syndrome occurs when the levels of a chemical called serotonin in your brain become too high. It's usually triggered when you take an SSRI or SNRI in combination with another medication (or substance) that also raises serotonin levels, such as another antidepressant or St John’s Wort.

Symptoms of serotonin syndrome can include:

  • confusion
  • agitation
  • muscle twitching
  • sweating
  • shivering
  • diarrhoea

If you experience these symptoms, you should stop taking the medication and seek immediate advice from your GP or specialist. If this isn't possible, call NHS Direct Wales on 0845 46 47 or 111 if available in your area.

Symptoms of severe serotonin syndrome include:

  • seizures (fits)
  • irregular heartbeat (arrhythmia)
  • unconsciousness

If you experience symptoms of severe serotonin syndrome, seek emergency medical help immediately by dialling 999 to ask for an ambulance.

Hyponatraemia

Elderly people who take antidepressants, particularly those who take SSRIs, may experience a severe fall in sodium (salt) levels, known as hyponatraemia. This may lead to a build-up of fluid inside the cells of the body, which can be potentially dangerous.

This can happen because SSRIs can block the effects of a hormone that regulates levels of sodium and fluid in the body. Elderly people are vulnerable because fluid levels become more difficult for the body to regulate as people age.

Mild hyponatraemia can cause symptoms similar to depression or side effects of antidepressants, such as:

  • feeling sick
  • headache
  • muscle pain
  • reduced appetite
  • confusion

More severe hyponatraemia can cause:

  • feeling listless and tired
  • disorientation
  • agitation
  • psychosis
  • seizures (fits)

The most serious cases of hyponatraemia can cause you to stop breathing or enter a coma.

If you suspect mild hyponatraemia, you should call your GP for advice and stop taking SSRIs for the time being.

If you suspect severe hyponatraemia, call 999 and ask for an ambulance.

Hyponatraemia can be treated by feeding a sodium solution into the body through an intravenous drip.

Diabetes

Long-term use of SSRIs and TCAs has been linked to an increased risk of developing type 2 diabetes, although it's not clear if the use of these antidepressants causes diabetes to develop directly.

It may be that the weight gain some people using antidepressants experience increases the risk of them developing type 2 diabetes.

For more information, see "Claim that antidepressants cause diabetes unproven".

Suicidal thoughts

In rare cases, some people experience suicidal thoughts and a desire to self-harm when they first take antidepressants. Young people under 25 seem particularly at risk.

Contact your GP, or go to hospital immediately, if you have thoughts of killing or harming yourself at any time while taking antidepressants.

It may be useful to tell a relative or close friend if you've started taking antidepressants and ask them to read the leaflet that comes with your medication. You should then ask them to tell you if they think your symptoms are getting worse, or if they're worried about changes in your behaviour.

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Alternatives

Several treatments can be used instead of antidepressants for treating depression and other mental health conditions.

Talking therapies

Cognitive behavioural therapy

Cognitive behavioural therapy (CBT) is a type of talking therapy that is increasingly being used in the treatment of depression. Most experts recommend that people with moderate to severe depression are treated with a combination of CBT and antidepressants.

However, if you are unable or unwilling to take antidepressants, you have the option of receiving CBT on its own.

CBT helps you understand your thoughts and behaviour, and how they affect you. It helps you recognise that events in your past may have shaped you, but it concentrates mostly on how you can change the way you think, feel and behave in the present. It also teaches you how to overcome negative thoughts.

CBT is usually available on the NHS, although waiting lists can be long. You normally have a short course of sessions, usually six to eight sessions, over 10-12 weeks on a one-to-one basis with a therapist trained in CBT. In some cases, you may be offered group CBT.

Online CBT

Computerised CBT is a form of CBT that works through a computer screen, rather than face-to-face with a therapist.

These therapies can be prescribed by your GP or a mental health specialist and are carried out with their advice and support.

Ask your GP for more information or read more about self-help therapies.

Interpersonal therapy (IPT)

Interpersonal therapy (IPT) focuses on your relationships with other people and on problems you may be having in your relationships, such as difficulties with communication or coping with bereavement.

A course of IPT is usually structured in the same way as a course of CBT.

There's some evidence that IPT can be as effective as antidepressants or CBT, but more research is needed.

Counselling

Counselling is a form of therapy that helps you think about the problems you're experiencing in your life to find new ways of dealing with them. Counsellors support you in finding solutions to problems, but don't tell you what to do.

Counselling on the NHS usually consists of 6 to 12 sessions lasting an hour each. You talk in confidence to a counsellor, who supports you and offers practical advice.

Counselling is ideal for people who are healthy but need help coping with a current crisis, such as anger, relationship issues, bereavement, redundancy, infertility or the onset of a serious illness.

Exercise

Research suggests that regular exercise may be a more effective treatment for mild depression than antidepressants.

Exercise helps boost levels of serotonin and dopamine in the brain, which can lift your mood.

Exercising on a regular basis can boost self-esteem and confidence which can also help relieve symptoms of depression.

Your GP may be able to refer you via the National Exercise Referral Scheme, a partnership with the Local Authorities and the NHS in Wales.

Self-help groups

Talking through your feelings can be helpful. You can either talk to a friend or relative, or you can ask your GP to suggest a local self-help group. The Health Wellbeing and Support local services search is also a useful place to look for self-help groups that are local to you.

Lithium

If you've tried several different antidepressants and seen no improvement, your doctor may offer you a medicine called lithium, in addition to your current treatment.

If the level of lithium in your blood becomes too high, it can become toxic. So, you'll need blood tests every few months to check your lithium levels while you're taking it.

You'll also need to avoid eating a low-salt diet because this can also cause the lithium to become toxic. Ask your GP for advice about your diet.

Side effects of lithium include:

  • dry mouth
  • a metallic taste in your mouth
  • some mild shaking of your hands
  • diarrhoea

These side effects usually pass with time once your body gets used to the medication.

Electric shock treatment

Sometimes a treatment called electroconvulsive therapy (ECT) may be recommended if you have severe depression and other treatments haven't worked, as it can be highly effective.

During ECT, you'll first be given an anaesthetic and medicine to relax your muscles. Then you'll receive an electric current to your brain through electrodes placed on your head.

You may be given a series of ECT sessions. It's usually given twice a week for 3 to 6 weeks.

It's not exactly clear how ECT works, but recent studies suggest it may help reduce connections in an area of the brain linked to depression.

For most people, ECT is good for relieving severe depression, but the beneficial effect tends to wear off after several months. Some people get unpleasant side effects, including short-term headaches, memory problems, nausea and muscle aches. However, these risks need to be balanced against the risks of other treatments and the effects of not treating depression.

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The information on this page has been adapted by NHS Wales from original content supplied by NHS Choices.
Last Updated: 18/01/2019 14:47:22