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SSRI antidepressants

Selective serotonin reuptake inhibitors (SSRIs) help treat certain mental illnesses. These include depression, anxiety, panic attacks and social phobia. They can also help with eating disorders and obsessive compulsive disorder (OCD).

There are currently five SSRI antidepressants available in New Zealand. These are citalopram, escitalopram, fluoxetine, paroxetine and sertraline.

Venlafaxine is a serotonin-noradrenaline reuptake inhibitor (SNRI). SNRIs have similar effects to SSRIs.

Talking therapies are often used alongside antidepressant medication.

Health professionals believe that antidepressants work by increasing the activity of neurotransmitters. Neurotransmitters are chemicals in our brains. Certain neurotransmitters, such as serotonin and noradrenaline, affect mood and emotion.

SSRIs help most people who try them.

How soon SSRI antidepressants work

Most antidepressants start helping within 2 weeks of starting to take them. It usually takes between 4 and 6 weeks before you get the full effect. If you do not feel any better after 2 to 4 weeks, tell your health professional. You may need to increase your dose or change to another antidepressant.

SSRI antidepressant safety

It is usually safe to take SSRI antidepressants as prescribed by your doctor. But they do not suit everyone. Let your doctor know if you have the following, as extra care may be needed:

Discuss any other medicines you take with your pharmacist or healthcare provider. This should include any you buy yourself. Especially cold remedies and hay fever medicines. It should also include nutritional or herbal supplements. And complementary medicines such as St John's wort. This is because other medicines may cause problems with your antidepressants.

You should avoid alcohol when taking SSRIs. This can cause drowsiness and make depression worse. SSRIs combined with alcohol can impair driving.

Side effects from SSRI antidepressants


Rarely, antidepressants can make you more anxious and restless in the first 2 weeks of taking them. You can even have feelings of self-harm or suicidal thoughts. If this happens, talk to your healthcare provider. Or contact a mental health crisis support line.

Side effects from SSRIs are usually mild and do not last long. Some people will not have any side effects.

If you have minor side effects, try staying on the medicine for a few weeks. Minor side effects often go away after your body gets used to the new medicine.

If the side effects do not go away or if they are worrying you, tell your healthcare provider or pharmacist. They may have suggestions for how to reduce or manage your side effect.

Common side effects of SSRIs include feeling anxious or restless, nausea and diarrhoea or constipation. They also include sleep problems, sweating and less interest in or trouble having sex.

Stopping antidepressants

There is no set time for how long you should take antidepressants. Most people will need to take them for at least 6 to 12 months. This can help stop your symptoms coming back.

Antidepressants are not addictive. But if you stop taking them suddenly, you may get some symptoms. This is known as antidepressant withdrawal or discontinuation syndrome.

You need to decrease most antidepressants slowly. You may need to drop the dose by small amounts each week, or every two weeks or every month.

You should talk to your healthcare provider before stopping your medication. They will help you make a plan for how you are going to do this.

For more information, see Stopping antidepressants.

Written by HealthInfo clinical advisers. Page created December 2023.


Page reference: 1293508

Review key: HIMMH-215644