SSRIs – Selective serotonin reuptake inhibitors

Selective serotonin reuptake inhibitors (SSRIs) are a type of antidepressant. They include:

SSRIs are one of the first choices when someone is first prescribed an antidepressant. This is because they are as effective as other types of antidepressant, but tend to have fewer side effects than some older types, such as tricyclic antidepressants (TCAs) and monoamine oxidase inhibitors (MAOIs).

How do SSRIs work?

Serotonin is a neurotransmitter — one of the chemicals responsible for relaying signals between the cells in your brain. SSRIs block the uptake of serotonin back into the brain cells and so increase the amount of serotonin available in the brain for transmitting signals. This increase in serotonin is thought to improve the symptoms of depression.

How effective are SSRIs?

About 50% of people treated with SSRIs find their depression symptoms are halved, usually within 8 weeks.

People who should take extra care with SSRIs

Make sure you tell your doctor if you have, or have had in the past, any of the following conditions (you might need to take extra precautions, or another medicine might be more suitable):

  • epilepsy or reduced seizure threshold
  • bipolar disorder
  • stomach bleeding
  • liver problems

Get advice about the risks of taking antidepressants, directly from your doctor or from a specialist information line, if you are pregnant, breastfeeding or thinking about becoming pregnant. See Antidepressants, pregnancy and breastfeeding.

Your doctor may also advise caution or another medicine if you are 80 years of age or older, or are taking medicines that increase the risk of stomach bleeding (e.g. aspirin or other nonsteroidal anti-inflammatory drugs [NSAIDs] such as ibuprofen).

SSRIs and children

Antidepressants have only a small role in treating children with depression, and should only be used in children under the supervision of a child psychiatrist. See also Antidepressants and suicide risk.

SSRIs and adolescents

Talking therapy, with either cognitive behavioural therapy (CBT) or interpersonal therapy (IPT), is the first choice if you are an adolescent with depression. However, if this hasn’t worked for you, or isn’t possible — or if your depression is very bad — an antidepressant may help. In this case, fluoxetine is usually the antidepressant of choice.

Antidepressants should be prescribed for adolescents only by doctors with training in this area, who are very familiar with the side effects and are able to monitor you closely. Monitoring for suicidal thinking is important after starting treatment, particularly in the first 4 weeks. See also Antidepressants and suicide risk.

If you are being treated by someone who does not have experience in treating adolescents with antidepressants, they should be advised by a psychiatrist, or refer you to a psychiatrist or mental health service.

Side effects of SSRIs

Side effects of SSRI antidepressants as a group are listed below. For the side effects of individual medicines, see the consumer medicine information (CMI).

Not everyone experiences these side effects — the way an antidepressant affects you is quite individual, so you might need to try more than one to find the one that suits you best. Some of the side effects will last only a week or two after you first start taking the medicine (e.g. insomnia, nausea, dizziness), while others (e.g. sexual side effects) tend to persist.

Remember that the risk of side effects with any medicine needs to be weighed against its benefit in treating your condition. Your doctor can help you weigh up the risks and benefits of taking a particular medicine. See also Is this medicine right for me?

How to manage side effects

  • Start on a low dose and increase gradually
  • Avoid taking the medicine at night initially if it causes agitation or insomnia
  • Tell your doctor if you are not feeling better or are worried about side effects

Side effects of SSRIs — Table

Common (1% of people or more)Infrequent (between 0.1% and 1% of people)Rare (fewer than 0.1% of people)



Insomnia (sleep problems)


Tremor (shaking)

Dry mouth







Weight gain or loss

Sexual dysfunction

Runny nose

Myalgia (muscle pain)


Unusual movements, including trembling of the
hands and fingers, twisting movements of the body, shuffling walk, limb stiffness



Feeling your heart racing or thumping (palpitations)

Increased heart rate

Low blood pressure

Bleeding problems (e.g. bruising, nose bleeds, gastrointestinal or vaginal bleeding)

Syndrome of inappropriate antidiuretic hormone secretion (SIADH). This causes low blood sodium, which can have serious consequences (seizures, coma or death).

Abnormal changes in liver function tests

Galactorrhoea (milk production from the breast)

Imbalance in numbers of different types of blood cells

Seizures (fits)


Paraesthesia (reduced sense of touch)

Taste disturbance

See also Antidepressants and suicide risk

Interactions with SSRIs

Some medicines should not be taken together because this may increase the risk of side effects, which can be serious, or may affect how well a medicine works. SSRIs increase the risk of serotonin toxicity if mixed with many other medicines. See a list of medicines that cause serotonin toxicity.

You should not take an SSRI at the same time as moclobemide or within 2 days of stopping it.

See the individual medicine page for more information about interactions.

Antidepressants and illegal drugs don’t mix!

Taking illegal drugs such as ecstasy, cocaine, amphetamines (speed), LSD (acid) with an antidepressant increases the risk of serotonin toxicity — which can be fatal.

SSRIs and alcohol

Alcohol may make you drowsier than usual if you are taking fluvoxamine or paroxetine. Other SSRIs do not have a significant interaction with alcohol, but it is generally not a good idea to drink alcohol if you are depressed or taking antidepressants.

Talk to your doctor about safe limits of drinking for your situation. If you have a drug or alcohol problem you may benefit from counselling, as this can help you recover from depression.

SSRIs and driving or operating machinery

Do not drive or operate machinery until you know how the medicine affects you.

For more information

  • Rossi S, ed. eAMH [online]. Adelaide: Australian Medicines Handbook, 2012. (accessed 9 February 2012).
  • McDermott B, Baigent M, Chanen A, et al; beyondblue Expert Working Committee. Clinical practice guidelines: depression in adolescents and young adults. Melbourne: beyondblue, 2010. (accessed 21 February 2012.
  • National Collaborating Centre for Mental Health (UK). Depression: the treatment and management of depression in adults (updated edition). Leicester (UK): British Psychological Society, 2010.