Selective serotonin reuptake inhibitors (SSRIs) - Side effects 

Side effects of SSRIs 

The side effects of selective serotonin reuptake inhibitors (SSRIs) can be troublesome at first but most improve with time.

In general, SSRIs are better tolerated than most other types of antidepressants. The majority of people will only experience a few mild side effects when taking them.

It is important to persist with treatment, even if you are affected by side effects, as it will take several weeks before you begin to benefit from treatment. With time you should find the benefits of treatment outweigh problems related to side effects.

You will usually see your doctor every few weeks during when you first start taking SSRIs to discuss how well the medication is working, although you can contact your doctor at any point if you experience any particularly troublesome or persistent side effects.

Some of the main side effects of SSRIs are described below, but this is not an exhaustive list and some of these will not all necessarily apply to the specific SSRI you are taking. For information on the side effects for a particular SSRI, check the information leaflet that comes with your medication or search for your medication in the medicines A-Z.

Common side effects

Common side effects of SSRIs can include:

These side effects should improve over time, although some – such as sexual problems – can persist.

Less common side effects

Less common side effects of SSRIs can include:

  • bruising or bleeding easily, including vomiting blood or blood in your stools
  • confusion
  • problems with movement, such as stiffness or shaking
  • seeing or hearing things that are not real (hallucinations)
  • being unable to pass urine

If you vomit blood, have blood in your stools or have problems passing urine, speak to your doctor or go to hospital immediately.

Serotonin syndrome

Serotonin syndrome is an uncommon but potentially serious set of side effects linked to SSRIs.

Serotonin syndrome occurs when the levels of a chemical called serotonin in your brain become too high. It is usually triggered when you take an SSRI in combination with another medication (or substance) that also raises serotonin levels, such as another antidepressant or St John’s Wort.

Symptoms of serotonin syndrome can include:

  • confusion
  • agitation
  • muscle twitching
  • sweating
  • shivering
  • diarrhoea

If you experience the symptoms listed above, you should stop taking the medication and seek immediate advice from your GP or specialist. If this is not possible, call NHS 111.

Symptoms of severe serotonin syndrome include:

  • a very high temperature (fever)
  • seizures (fits)
  • irregular heartbeat (arrhythmia)
  • loss of consciousness

If you or someone you know experience symptoms of severe serotonin syndrome, seek emergency medical help immediately by dialling 999 and asking for an ambulance.

Hyponatraemia

Elderly people who take SSRIs may experience a severe fall in sodium (salt) levels known as hyponatraemia. This may lead to a build-up of fluid inside the cells of the body, which can be potentially dangerous.

This side effect can occur as SSRIs can block the effects of a hormone that helps regulate levels of sodium and fluid in the body. Elderly people are vulnerable because fluid levels become more difficult for the body to regulate.

Mild hyponatraemia can cause symptoms similar to depression or side effects of SSRIs, such as:

  • feeling sick
  • headache
  • muscle pain
  • reduced appetite
  • confusion

More severe hyponatraemia can cause the following symptoms:

  • feeling listless and tired
  • disorientation
  • agitation
  • psychosis (being unable to tell the difference between reality and your imagination)
  • seizures (fits)

The most serious cases of hyponatraemia can cause you to stop breathing or enter a coma.

If you suspect that you or someone in your care has mild hyponatraemia, you should call your GP for advice and stop taking SSRIs for the time being. If you suspect severe hyponatraemia, call 999 and ask for an ambulance.

Hyponatraemia can be treated by feeding a sodium solution into the body through an intravenous drip.

Suicidal thoughts

Some people experience suicidal thoughts and a desire to self-harm when they first take SSRIs. Young people under 25 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 SSRIs.

It may be useful to tell a relative or close friend you have started taking antidepressants and ask them to read the leaflet that comes with your medication. You should then ask them to tell you if they think your symptoms are getting worse, or if they are worried about changes in your behaviour.


Page last reviewed: 10/03/2014

Next review due: 10/03/2016

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Comments

The 1 comments posted are personal views. Any information they give has not been checked and may not be accurate.

haldi said on 03 November 2013

By all internet accounts this drug is scarey.
I am afraid that I agree
I am now attempting to get off it, by gradually reducing the dose.
It was originally prescribed three months ago for neuropathic pain. Starting the medicine made me very unwell, experiencing extreme nausea, complete loss of appetite and bad anxiety.
Most of these side effects went away after 2 weeks, but were replaced by excessive sweating, sores on my head, hair loss, terrible headaches, migraine and over excitement.
In fairness to the drug I did get a good week whilst on the medication, but that may simply be something I would have experienced anyhow

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Reporting side effects

The Yellow Card Scheme allows you to report suspected side effects from any type of medicine that you are taking. It is run by a medicines safety watchdog called the Medicines and Healthcare products Regulatory Agency (MHRA).

See the website of the Yellow Card Scheme for more information. 

The Yellow Card Scheme

The MHRA has produced a video that explains how the Yellow Card Scheme can be used to report the side effects of medication