Antidepressants

Authored by Dr Gurvinder Rull, 09 Aug 2017

Patient is a certified member of
The Information Standard

Reviewed by:
Dr John Cox, 09 Aug 2017

A normal course of antidepressants lasts at least six months after symptoms have eased. Side-effects may occur but are often minor.

Tricyclic antidepressants are used to treat depression and some other conditions. They often take 2-4 weeks to work fully. A normal course of antidepressants lasts at least six months after symptoms have eased. Side-effects may occur but are often minor and may ease off. At the end of a course of treatment, you should gradually reduce the dose before stopping completely.

Tricyclic antidepressants are not just for depression

Tricyclic antidepressants are used to treat depression. They are also used to treat some other conditions such as migraine, panic disorder, obsessive-compulsive disorder, recurrent headaches, and some forms of pain. The word tricyclic refers to the chemical structure of the medicine.

How do tricyclic antidepressants work?

Tricyclic antidepressants alter the balance of some chemicals in the brain, called neurotransmitters. An imbalance of the neurotransmitters is thought to play a part in causing depression and other conditions. Tricyclic antidepressants generally block the effects of two neurotransmitters called serotonin and noradrenaline (norepinephrine). The role these chemicals have in causing, or treating, depression is unclear.

About 5-7 in 10 people with moderate or severe depression have an improvement in symptoms within a few weeks of starting treatment with an antidepressant. However, up to 3 in 10 people improve with dummy tablets (placebos), as some people would have improved in this time naturally. So, if you have depression, you are roughly twice as likely to improve with an antidepressant compared with taking no treatment. However, they do not work in everybody. As a rule, the more severe the depression, the greater the chance that an antidepressant will work well.

Note: antidepressants do not necessarily make sad people happy. The word 'depressed' is often used when people really mean sad, fed up, or unhappy. True depression is different to unhappiness and has persistent symptoms (which often include persistent sadness). 

The success rate of tricyclic antidepressants can vary when used to treat the other conditions (migraine, panic disorder, obsessive-compulsive disorder, recurrent headaches and some forms of pain).

How quickly do tricyclic antidepressants work?

Some people notice an improvement within a few days of starting treatment. However, an antidepressant often takes 2-4 weeks to build up its effect and work fully. Some people stop treatment after a week or so thinking it is not helping. It is best to wait for 3-4 weeks before deciding if an antidepressant is helping or not. If poor sleep is a symptom of the depression, it is often helped first, within a week or so.

With some types of tricyclic antidepressant, the initial dose that is started is often small and is increased gradually to a full dose. (One problem that sometimes occurs is that some people remain on the initial dose which is often too low to work fully.)

If you find that the treatment is helpful after 3-4 weeks, it is usual to continue. A normal course of antidepressants lasts at least six months after symptoms have eased. If you stop the medicine too soon, your symptoms may rapidly return. Some people with recurrent depression are advised to take longer courses of treatment (up to two years or longer).

When you are taking tricyclic antidepressants

It is important to take the medication each day at the dose prescribed. Do not stop taking it abruptly. This is because you may develop some withdrawal symptoms. The dose is usually gradually reduced before stopping completely at the end of a course of treatment. But don't do this yourself - your doctor will advise on dosage reduction when the time comes. It is best not to stop treatment or change the dose without consulting a doctor.

Are there different types of tricyclic antidepressants?

There are several different types. The ones used in the UK include imipramine, amitriptyline, doxepin, mianserintrazodone, and lofepramine. Each of these comes in different brand names.

There is no best type that suits everyone. A doctor makes a judgement as to which one would best suit, taking into account things such as:

  • Your age.
  • Other medicines that you may take.
  • Other medical problems.
  • Possible side-effects.
  • Previous use of antidepressants.

If the one chosen does not suit, it is sometimes necessary to change the dose, or change the preparation. Also, if tricyclic antidepressants do not help then another type of antidepressant may be advised.

Most people have either minor, or no, side-effects. Possible side-effects vary between different preparations. The leaflet that comes in the medicine packet gives a full list of possible side-effects. You should read this before you start taking the medicine. It is beyond the scope of this leaflet to list all side-effects; however, the following highlights some of the more common or serious ones. As a rule, tell your doctor if a side-effect persists or is troublesome. Your doctor can advise on the best course of action - for example, to stop the medication, a switch to a different medicine, etc.

The most common side-effects

These include a dry mouth, constipation, sweating, slight hesitancy in passing urine and slight blurring of vision. It is worth keeping on with treatment if these side-effects are mild at first. Minor side-effects may wear off after a week or so. Frequent drinks of water will help a dry mouth. Also, some people find that sucking pineapple chunks helps with the flow of saliva and helps to ease the feeling of dry mouth.

A possible sedating effect

Tricyclic antidepressants can cause drowsiness (a sedating effect) in some people. You must be aware of this possibility, especially if you are a driver, as it may impair your ability to drive safely. Any sedating effect is likely to be greatest in the first month of starting treatment, or on increasing the dose. The Driver and Vehicle Licensing Agency (DVLA) advises that you should not drive during this time if you feel that you are drowsy or sedated at all. Also, do not operate machinery if you feel drowsy.

Small increased risk of fractures

Research studies suggest that there is a small increased risk of fractures in people taking tricyclic antidepressants. However, the reason for this increased risk is not clear.

Antidepressants and suicidal behaviour

In recent years there have been some case reports which claim a link between taking antidepressants and feeling suicidal, particularly in teenagers and young adults. This may be more of a risk in the first few weeks of starting medication or after a dose increase. It is debatable whether this possible risk is due to the medicine or to the depression. If it is due to the medication then the risk remains very small. And, overall, the most effective way to prevent suicidal thoughts and acts is to treat depression. However, because of this possible link, see your doctor promptly if you become increasingly restless, anxious or agitated, or if you have any suicidal thoughts. In particular, if these develop in the early stages of treatment or following an increase in dose.

Sexual problems

Problems with sexual function are a common symptom of depression. However, in addition to this, all antidepressants may cause some problems with sexual function. For example, decreased sex drive (libido), difficulty getting an erection, delayed orgasm, and impaired ejaculation have been reported as side-effects in some people taking tricyclic antidepressants.

Tricyclic antidepressants are not tranquillisers and are not thought to be addictive. Most people can stop tricyclic antidepressants without any problem. At the end of a course of treatment it is usual to reduce the dose gradually over about four weeks before finally stopping. This is because some people develop withdrawal symptoms if an antidepressant is stopped abruptly. If you have withdrawal symptoms it does not mean that you are addicted to the medicine, as other features of addiction, such as cravings for the medicine, do not occur.

Withdrawal symptoms that may occur include:

  • Dizziness
  • Anxiety and agitation
  • Sleep disturbance
  • Flu-like symptoms
  • Diarrhoea
  • Tummy (abdominal) cramps
  • Pins and needles
  • Mood swings
  • Feeling sick (nauseated)
  • Low mood

These symptoms are unlikely to occur if you reduce the dose gradually. If withdrawal symptoms do occur, they will usually last less than two weeks. An option if they do occur is to restart the medicine and reduce the dose even more slowly.

Selective serotonin reuptake inhibitor (SSRI) antidepressants are used to treat depression and some other conditions. They can take 6-8 weeks to build up their effect to work fully. A normal course of antidepressants lasts at least six months after symptoms have eased. Side-effects may occur but are often minor. At the end of a course of treatment, you should gradually reduce the dose, as directed by your doctor, before stopping completely.

Are SSRI antidepressants used just for depression?

SSRIs are a group of antidepressant medicines that are used to treat depression. They are also used to treat some other conditions such as bulimia nervosa, panic disorder and obsessive-compulsive disorder.

How do SSRI antidepressants work?

Antidepressants alter the balance of some of the chemicals in the brain (neurotransmitters). SSRI antidepressants mainly affect a neurotransmitter called serotonin.

About 5-7 in 10 people with moderate or severe depression have an improvement in symptoms within a few weeks of starting treatment with an antidepressant. However, up to 3 in 10 people improve with dummy tablets (placebos), as some people would have improved in this time naturally. So, if you have depression, you are roughly twice as likely to improve with an antidepressant compared with taking no treatment. But, they do not work in everybody. As a rule, the more severe the depression, the greater the chance that an antidepressant will work well.

Note: antidepressants do not necessarily make sad people happy. The word 'depressed' is often used when people really mean sad, fed-up, or unhappy. True depression is different to unhappiness and has persistent symptoms (which often include persistent sadness).

The success rate of SSRI antidepressants can vary when used to treat the other conditions listed above (bulimia, panic disorder and obsessive-compulsive disorder).

How quickly do SSRI antidepressants work?

Some people notice an improvement within a few days of starting treatment. However, an antidepressant often takes 6-8 weeks to build up its effect and work fully. Some people stop treatment after a week or so, thinking it is not helping. It is best to wait for 3-4 weeks before deciding if treatment with an SSRI is helping or not.

If you find that the treatment is helpful after 3-4 weeks, it is usual to continue. A normal course of antidepressants lasts at least six months after symptoms have eased. If you stop the medicine too soon, your symptoms may rapidly return. Some people with recurrent depression are advised to take longer courses of treatment (up to two years or longer).

When you are taking SSRI antidepressants it is important to take the medication each day at the dose prescribed. Do not stop taking an SSRI medicine abruptly. This is because you may develop some withdrawal symptoms. The dose is usually gradually reduced before being stopped completely at the end of a course of treatment. But don't do this yourself - your doctor will advise on dosage reduction when the time comes. It is best not to stop treatment or change the dose without consulting a doctor.

Are there different types of SSRI antidepressants?

There are several different types. They include citalopram, escitalopram, fluoxetine, paroxetineand sertraline. Each of these comes in different brand names. There is no best type that suits everyone. If the one chosen does not suit, it is sometimes necessary to change the dose, or change the preparation. Your doctor will advise. Also, if SSRI antidepressants do not help then another type of antidepressant may be advised.

Most people have either minor, or no, side-effects. Possible side-effects vary between different preparations. The leaflet that comes in the medicine packet gives a full list of possible side-effects. You should read this before you start taking the medicine. It is beyond the scope of this leaflet to list all side-effects; however, the following highlights some of the more common or serious ones.

As a rule, tell your doctor if a side-effect persists or is troublesome. Your doctor can advise on the best course of action - for example, to stop the medication, or a switch to a different medicine, etc.

The most common side-effects

These include diarrhoea, feeling sick (nauseated), being sick (vomiting) and headaches. It is worth keeping on with treatment if these side-effects are mild at first as they may wear off after a week or so.

A possible sedating effect

SSRIs can cause drowsiness (a sedating effect) in some people. This side-effect is not common and is not as much of a problem as with some other types of antidepressants. However, you must be aware of the possibility, especially if you are a driver, as it may impair your ability to drive safely. Any sedative effect is likely to be greatest in the first month of starting treatment, or on increasing the dose. The Driver and Vehicle Licensing Agency (DVLA) advises that you should not drive during this time if you feel that you are drowsy or sedated at all.

Bleeding into the gut

Some research has suggested that SSRIs may be associated with a small increased risk of bleeding into the gut; however, the evidence is inconclusive. This is especially in older people and in people taking other medicines that have the potential to damage the lining of the gut or interfere with clotting. Therefore, ideally, SSRIs should be avoided if you take aspirin, warfarin, novel anticoagulants (apixaban, edoxaban, dabigatran and rivaroxaban) or non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen. If no suitable alternative to an SSRI can be found and you have an increased risk of bleeding, your doctor may advise that you take an additional medicine. This will help to protect the lining of the gut.

Small increased risk of fractures

Research studies suggest that there is a small increased risk of fractures in people taking an SSRI. However, the reason for this increased risk is not clear.

Nervous system side-effects

Dizziness, agitation, anxiety, difficulty sleeping and tremor have all been reported as possible side-effects.

Sexual problems

Problems with sexual function are a common symptom of depression. However, in addition to this, all antidepressants may cause some problems with sexual function. For example, problems getting an erection, vaginal dryness and decreased sex drive have been reported as side-effects in some people.

Antidepressants and suicidal behaviour

In recent years there have been some case reports which claim a link between taking antidepressants and feeling suicidal, particularly in teenagers and young adults. This may be more of a risk in the first few weeks of starting medication or after a dose increase. It is debatable whether this possible risk is due to the medicine or to the depression. If it is due to the medication then the risk remains very small. And, overall, the most effective way to prevent suicidal thoughts and acts is to treat depression. However, because of this possible link, see your doctor promptly if you become increasingly restless, anxious or agitated, or if you have any suicidal thoughts. In particular, you should speak with your doctor if these develop in the early stages of treatment or following an increase in dose.

SSRIs are not tranquillisers, and are not thought to be addictive. Most people can stop an SSRI without any problem. At the end of a course of treatment you should reduce the dose gradually over about four weeks before finally stopping. This is because some people develop withdrawal symptoms if the medication is stopped abruptly. If you have withdrawal symptoms it does not mean that you are addicted to the medicine, as other features of addiction such as cravings for the medicine do not occur.

Withdrawal symptoms that may occur include:

  • Dizziness
  • Anxiety and agitation
  • Sleep disturbance
  • Flu-like symptoms
  • Diarrhoea
  • Tummy (abdominal) cramps
  • Pins and needles
  • Mood swings
  • Feeling sick (nauseated)
  • Low mood

These symptoms are unlikely to occur if you reduce the dose gradually. If withdrawal symptoms do occur, they will usually last less than two weeks. An option if they do occur is to restart the drug and reduce the dose even more slowly.

Monoamine-oxidase inhibitor (MAOI) antidepressants are a group of medicines that are used to treat depression. They can take up to three weeks to build up their effect to work fully. A normal course of antidepressants lasts at least six months after symptoms ease. You cannot drink alcohol or eat food that contains tyramine (for example, cheese, liver, yoghurt or Marmite®) while you are taking an MAOI. You cannot take some cough and cold medicines while you are taking an MAOI.

How do MAOI antidepressants work?

Antidepressants alter the balance of some of the chemicals in the brain (neurotransmitters). MAOI antidepressants prevent the breakdown of neurotransmitters such as noradrenaline (norepinephrine) and serotonin. An altered balance of serotonin and other neurotransmitters such as noradrenaline is thought to play a part in causing depression.

When are MAOI antidepressants usually prescribed?

MAOI antidepressants are usually prescribed when several of the newer types of antidepressants have been tried but have not worked so well, or caused troublesome side-effects. Some examples of newer types of antidepressant are fluoxetine, citalopram and sertraline. An MAOI may also be used if you have atypical depression. Atypical depression is a type of depression in which there are specific features not present in other types of depression. Examples of these include an improvement in mood if something good happens in your life, excessive sleepiness and a heavy feeling in the arms or legs.

MAOI antidepressants are normally prescribed or recommended by doctors who specialise in treating depression. For example, a consultant in mental health, or a GP who has a lot of experience of treating people with depression.

Most people who take antidepressants find that the newer types are easier to take because:

  • They have fewer side-effects and drug interactions.
  • You don't have to avoid certain foods or drinks that contain tyramine or cough and cold medicines.

How well do MAOI antidepressants work?

About 5-7 in 10 people with moderate or severe depression have an improvement in symptoms within a few weeks of starting treatment with an antidepressant. However, up to 3 in 10 people improve with dummy tablets (placebo), as some people would have improved in this time naturally. So, if you have depression, you are roughly twice as likely to improve with an antidepressant compared with taking no treatment. But, they do not work in everybody. As a rule, the more severe the depression, the greater the chance that an antidepressant will work well.

Note: antidepressants do not necessarily make sad people happy. The word depressed is often used when people really mean sad, fed-up, or unhappy. True depression is different to unhappiness and has persistent symptoms (which often include persistent sadness). 

How quickly do MAOI antidepressants work?

Some people notice an improvement within a few days of starting treatment. However, it may take up to three weeks or more to build up its effect and work fully. Some people stop treatment after a week or so thinking it is not helping. It is best to wait for 3-4 weeks before deciding if an antidepressant is helping or not. If poor sleep is a symptom of the depression, it is often helped first, within a week or so.

Some important considerations are:

  • Do not eat foods or drinks that contain tyramine.
  • Do not take certain other medicines.
  • Carry a special card at all times.
  • Rules when switching to other antidepressants.

Avoid tyramine

Do not eat food or drinks that contain tyramine (including alcoholic drinks) because this can cause a very large, sudden increase in blood pressure (hypertensive crisis). This is very important if you are taking one of the older MAOI antidepressants such as phenelzine, isocarboxazid and tranylcypromine. Hypertensive crisis is less likely to happen with moclobemide, but you still cannot eat or drink large amounts of food and drinks that contain tyramine. The first sign of a hypertensive crisis may be a throbbing headache.

Tyramine is found in cheese, liver, yoghurt, Marmite®, Oxo®, Bovril®, brewer's yeast, flavoured textured vegetable protein, broad bean pods (the beans inside can be eaten), protein which has been allowed to age, or ferment (for example, hung game, pickled herrings or dry sausage such as salami or pepperoni), fermented soya bean extract and large amounts of chocolate.

Tyramine is also found in alcoholic drinks, including beer, lager or wine (especially red wine). It is best to avoid all alcoholic drinks. It is also found in non-alcoholic beer.

Only eat fresh foods and avoid food that is stale or 'going off', especially meat (including poultry meat and offal meat) and fish while taking an MAOI and for two weeks after you stop. This is because these foods may contain tyramine.

Other medicines that you may take

MAOIs sometimes react with other medicines that you may take. So, make sure your doctor knows of any other medicines that you are taking, including ones that you have bought rather than been prescribed. Always check with your pharmacist before buying any medicines from the chemist or supermarket to see if they are safe to take with an MAOI antidepressant. Some medicines that you can buy for coughs and colds can also cause a very large sudden increase in blood pressure (hypertensive crisis), or make you very excitable or depressed.

In particular, avoid medicines for coughs and colds that contain dextromethorphan, ephedrine or pseudoephedrine while you are taking an MAOI antidepressant and for two weeks after you stop it:

  • Dextromethorphan when taken with an MAOI antidepressant may make you very excitable or depressed.
  • Ephedrine, pseudoephedrine and phenylpropanolamine when taken at the same time as an MAOI antidepressant may cause very large increases in blood pressure.

Carry a card

If you are taking an MAOI antidepressant you will be given a small card that you must carry with you at all times. This card lists the different foods, drinks and over-the-counter medicines you can't take. Always make sure you show this card to anyone giving you medical treatment (for example, a doctor, a dentist, a pharmacist or a nurse).

If you change your antidepressant

If your doctor wants to change your medication from an MAOI to another antidepressant, you must leave two weeks between stopping your MAOI antidepressant before starting your new antidepressant.

Phenelzine, isocarboxazid and tranylcypromine

The most common side-effect with these older MAOIs is feeling dizzy when you stand up (postural hypotension). It is more likely to happen if you are older. Less commonly, some people have drowsiness, difficulty sleeping, headache, weakness and tiredness, a dry mouth, or constipation. Very rarely these medicines can affect your liver - for example, jaundice has been reported and a few deaths from liver reactions (but these are very rare). Peripheral neuropathy (weakness, cramps, and spasms, a loss of balance or tingling, numbness, and pain) has also been reported very rarely.

Moclobemide

Common adverse effects include, sleep disturbance, and feeling sick (nausea). Less commonly, agitation and confusion have been seen in people taking moclobemide.

Note: the above is not the full list of side-effects or interactions for these medicines. Please see the leaflet that comes with your particular brand for a full list of possible side-effects and cautions.

Can I buy MAOI antidepressants?

You cannot buy MAOI antidepressants. They are only available from your chemist, with a doctor's prescription.

What is the usual length of treatment?

If you find that the treatment is helpful after 3-4 weeks, it is usual to continue. A normal course of antidepressants lasts at least six months after symptoms have eased. If you stop the medicine too soon, your symptoms may rapidly return.

Some people with recurrent depression are advised to take longer courses of treatment.

Who cannot take MAOI antidepressants?

It is normally recommended that you avoid taking MAOI antidepressants if you:

  • Have bipolar disorder and are in a manic phase.
  • Experience excitation or agitation as a major part of your depression (your doctor may prescribe a sedative medication such as a benzodiazepine for 2-3 weeks).
  • Have had a stroke or any other condition that affects the blood supply to the brain.
  • Are taking other antidepressants.
  • Have a growth on your adrenal gland (phaeochromocytoma) which can cause high blood pressure.
  • Have heart disease.
  • Are pregnant.
  • Are breast-feeding.

MAOI antidepressants are not tranquillisers and are not thought to be addictive. (This is disputed by some people and so this is a controversial issue. If addiction does occur, it is only in a minority of cases.)

Most people can stop an MAOI without any problem. At the end of a course of treatment you should reduce the dose gradually over about four weeks before finally stopping. This is because some people develop withdrawal symptoms if the medication is stopped abruptly. If you have withdrawal symptoms, it does not mean that you are addicted to the medicine, as other features of addiction such as cravings for the medicine do not occur.

Withdrawal symptoms that may occur include:

  • Drowsiness.
  • Anxiety and agitation.
  • Sleep disturbance.
  • Vivid dreams.
  • Slowed speech.
  • A lack of muscle co-ordination.

Rarely, some people may have hallucinations and delusions.

These symptoms are unlikely to occur if you reduce the dose gradually. If withdrawal symptoms do occur, they will usually last less than two weeks. An option if they do occur is to restart the medicine and reduce the dose even more slowly.

How to use the Yellow Card Scheme

If you think you have had a side-effect to one of your medicines you can report this on the Yellow Card Scheme. You can do this online at www.mhra.gov.uk/yellowcard.

The Yellow Card Scheme is used to make pharmacists, doctors and nurses aware of any new side-effects that medicines or any other healthcare products may have caused. If you wish to report a side-effect, you will need to provide basic information about:

  • The side-effect.
  • The name of the medicine which you think caused it.
  • The person who had the side-effect.
  • Your contact details as the reporter of the side-effect.

It is helpful if you have your medication - and/or the leaflet that came with it - with you while you fill out the report.

Further reading and references

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