SSRIs (selective serotonin reuptake inhibitors) 


Depression and low mood

In this video, an expert describes the various levels of depression, the early warning signs and the treatments available.

Media last reviewed: 09/07/2012

Next review due: 09/07/2014

Types of selective serotonin reuptake inhibitors

There are currently six SSRIs prescribed in the UK. These are:

Serotonin-norepinephrine reuptake inhibitors

Serotonin-norepinephrine reuptake inhibitors (SNRIs) are a newer type of antidepressant.

SNRIs are 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 that some people respond better to SSRIs while others respond better to SNRIs.

There are currently two SNRIs prescribed in the UK:

Issues such as side effects, cautions and interactions are broadly similar for both SSRIs and SNRIs.

Read your leaflet that comes with your SNRI medication in case there are any important issues not discussed in this topic.

Selective serotonin reuptake inhibitors (SSRIs) are a type of medicine used to treat depression.

SSRIs can also be used to treat other conditions, such as:

Read more about the uses of selective serotonin reuptake inhibitors.

How they work

SSRIs boost levels of a substance called serotonin in the brain. When serotonin is released it helps lift mood.

It is thought people with depression release only small amounts of serotonin. The SSRIs prevent the nerve cells in the brain absorbing serotonin.

Depression is not simply caused by serotonin levels. But a rise in serotonin levels can improve mood and make people more responsive to other types of treatment, such as the talking therapy cognitive behavioural therapy.

Read more about how selective serotonin reuptake inhibitors work.

Side effects

Common side effects of SSRIs include:

  • feeling sick
  • low sex drive
  • difficulty achieving orgasm during sex or masturbation
  • in men, difficulty obtaining or maintaining an erection (erectile dysfunction)
  • blurred vision

Most people find that side effects improve with time as their body gets used to the effects of the medication.

Some people experience suicidal thoughts and a desire to self-harm when they first start taking SSRIs. Those under 25 years of age 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 you are taking antidepressants.

Read more about the side effects of selective serotonin reuptake inhibitors.


Your GP will usually prescribe the lowest possible dose to reduce your risk of experiencing side effects. The dose can be gradually increased if it's not enough.

It can take two to four weeks for an SSRI to start improving your mood.

You should continue taking your SSRI even if it does not seem to work at first. Sometimes, the symptoms of a condition get worse before the SSRI has started working.

Depending on your previous medical history it may be recommended that you continue to take an SSRI for several months to prevent the condition returning.

Never suddenly stop taking an SSRI as this can lead to unpleasant withdrawal effects such as feeling anxious and dizziness. When it's time for your treatment to end, your dosage will be gradually reduced.

Read more about the dosage of selective serotonin reuptake inhibitors.

Things to consider

SSRIs are not usually recommended in children and should only be given to pregnant women if it is thought benefits of treatment outweigh potential risks.

SSRIs may also not be suitable for people with certain health conditions such as glaucoma (increased pressure in the eye) and kidney problems.

Read more about the cautions associated with selective serotonin reuptake inhibitors.

Some SSRIs can react unpredictably with other medicines, including over-the-counter painkillers and herbal remedies such as St John’s wort.

Always read the information leaflet that comes with your medication to be aware of any potential interactions.

It's usually recommended that you avoid drinking alcohol while taking an SSRI. Alcohol can make SSRIs less effective and make side effects more severe.

Read more about possible interactions with selective serotonin reuptake inhibitors.

Page last reviewed: 24/04/2012

Next review due: 24/04/2014


How helpful is this page?

Average rating

Based on 102 ratings

All ratings

Add your rating


The 8 comments posted are personal views. Any information they give has not been checked and may not be accurate.

Hayley1994 said on 26 December 2013

Last thursday, I was prescribed 50mg sertraline by the dr i went to see about intrusive thoughts. I took one and it made me so tired and i slept until 2am and woke up feeling terrible, feeling sick dizzy, dry mouth etc, i didnt take anymore. Since then i have been feeling very ill, i started to get chest pains over the weekend and my heart rate was so abnormally bad i had an ambulance from nhs direct to come, they looked at my blood pressure but it was normal, they then found i had low blood sugar which i think was an affect from the sertraline tablet. I stopped eating much after finding out i had low blood sugar and dont know what it is at right now. I have started to get bad pins and needles in my feet , muscle pain in my legs, bruises all over my legs that have started to appear, tingles in my fingers and hands and feet that have got to a point where if i touch anything they will tingle more at times. I have shivering inside my body for no reason, been shaking alot, constantly tired, breathing difficulties. i am getting dizzy spells alot and my thinking has become a big problem, i am starting to have memory problems, not been able to concentrate , feeling like im unreal and everything around me is a weird crazy dream, basically brain fog like symptoms, im unable to sleep cuz of weird daydreams and noises, my mind has become sensitive to sound, i get hot sweats up my neck and scalp, my hands and feet are cold all the time. my brain is in a mess :( i don't know if the sertraline caused this or the low blood sugar or both! also ive become very irritable, quick tempered and cry alot now :( i feel trapped in my mind and feel that ill never get to the bottom of it and i will have to live with it for the rest of my life and its getting worse :( i want my life back that i had before taking the sertraline tablet :'( if anyone has any thought to what it is im going through please comment, im so scared :./

Report this content as offensive or unsuitable

rollingwaves said on 21 December 2013

I've taken SSRIs for many years but have recently come to question their usefulness and stopped taking them. I'm particularly uneasy with the kind of longer term use I have been encouraged to adopt (by psychiatrists and GPs). Look up tardive dysphoria to help make your own more informed decisions. My own view is that they are likely to be over prescribed.

Report this content as offensive or unsuitable

wellnesspharmacist said on 17 October 2013

Alongside the traditional treatment of medical conditions there is much we can do to help ourselves. I found this article really interesting and thought I might share here

Report this content as offensive or unsuitable

johnthe counsellor said on 29 August 2013

A quick question. is it likely that a person receiving counselling, who is recovering and feeling better about themselves, would have increased serotonin levels ?

If yes, and they are on serotonin based medications, should they in consultation with the doctor reduce those medications to avoid serotonin syndrome ?

Report this content as offensive or unsuitable

medusacadenza said on 03 August 2013

Doctors and the public are being misled about SSRI's and other widely prescribed psychiatric drugs. This is the problem with evidence based instead of data based medicine.

There are conditions that can be caused by "antidepressant" drugs such as PSSD (Post SSRI Sexual Dysfunction) - This is almost a kind of syndrome in which the person has no libido or emotions and life feels irrelevant to them.

A doctor is supposed to "Do no harm".

Report this content as offensive or unsuitable

fjr said on 22 December 2012

You state that for most people the sexual side effects improve with time, but no guidance is offered for those people whose side effects persist even after discontinuation.

Report this content as offensive or unsuitable

User732834 said on 14 December 2012

Selective serotonin reuptake inhibitors have a lot of question marks......we know so little about them, but we sale and prescribe them like bananas. I recommend before taking ssris to inform very well on serotonin, and see just after you understand what are the solutions for you!

A good article on serotonin:

Report this content as offensive or unsuitable

tpws said on 19 October 2011

Hi, I am taking Citalopram but one of the side effects is that it exsaperates my restless legs, not as bad as Fluoxetine.

Is there one that will not have this side effect ????

Report this content as offensive or unsuitable

'I run to boost my mood'

Liz Gardiner talks about her depression and how medication, CBT and exercise have all helped