Antidepressants are a type of medication used to treat depression.
They are also effective in treating a number of other conditions such as:
Read more about what antidepressants are used for.
How antidepressants work
It is thought antidepressants work by changing the levels of a group of chemicals in the brain called neurotransmitters. Certain neurotransmitters such as serotonin and norepinephrine can improve mood and emotion though how and why is not fully understood..
While antidepressants treat the symptoms of depression, they do not necessarily address its causes.
This is why they are usually used in combination with therapy to treat moderate to severe depression or other mental health conditions.
Increasing the levels of neurotransmitters is a gradual process. Most people will need to take antidepressants for two to four weeks before noticing any improvement in their symptoms.
Increasing levels of neurotransmitters can also disrupt pain signals sent by nerves, which may explain why some antidepressants can also help relieve symptoms of long-term (chronic) pain.
Are they effective?
Recent research shows antidepressants may not be as effective as previously thought; especially in cases of mild depression.
The Royal College of Psychiatry estimates that between 50-65% of people treated with an antidepressant for depression will benefit.
Patients would need to take an antidepressant for at least three weeks (without missing a dose) before feeling the benefit. Those who took an antidepressant for six weeks without feeling any benefit should consider other treatment.
Dosage
Antidepressants are usually taken in tablet form. A usual course of treatment is six months. A two year course may be recommended in people with a previous history of depression.
Side effects
Common side effects include:
Side effects should improve with time once the body gets used to the medication.
Read more about the side effects of antidepressants.
Different types of antidepressants
Some of the most widely used antidepressants are discussed below.
Selective serotonin reuptake inhibitors (SSRIs)
These are the most widely prescribed type of antidepressants.
SSRIs are usually preferred over other antidepressants as they cause less side effects. An overdose is also less likely to be fatal.
Fluoxetine is probably the best known SSRI (sold under the brand name Prozac).
Other SSRIs include:
Serotonin-norepinephrine reuptake inhibitors (SNRIs)
These work in a similar way to SSRIs.
SNRIs include:
They were designed to create a more clinically 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.
Tricyclic antidepressants
Tricyclic antidepressants (TCAs) are an older type of antidepressants now not usually recommended as a first-line treatment for depression
This is because TCAs can be dangerous if a person overdoses on them. They also cause more unpleasant side effects than SSRIs and SNRIs.
Exceptions are sometimes made in people with severe depression which fails to respond to other treatments. TCAs may also be recommended for other mental health conditions such as obsessive compulsive disorder and bi-polar disorder.
Examples of TCA include:
Some types of TCAs, such as amitriptyline, can also be used to treat chronic nerve pain.
Monoamine oxidase inhibitors
Monoamine oxidase inhibitors (MAOIs) are another older type of antidepressant with a wide range of side effects. They tend only to be used if other types of antidepressants are not effective.
Examples of MAOIs include:
A significant drawback with MAOIs is the need to avoid foods and drinks, such as red wine and pickled fish, which contain a protein called tyramine. This is because consuming tyramine while taking MAOIs can cause a dangerous rise in blood pressure.
Alternatives to antidepressants
Alternative treatments for depression include talking therapies such cognitive behavioural therapy (CBT).
Increasingly, people with moderate to severe depression are treated using a combination of antidepressants and CBT.
Regular exercise has also been shown to be useful in those with mild depression.
Read more about alternatives to antidepressants.
