Selective Serotonin Reuptake Inhibitors (SSRIs)


Overview: Selective Serotonin Reuptake Inhibitors (SSRIs) are a widely used and safe class of antidepressant medication. SSRIs are mainly prescribed to treat depression, though can also be used for a range of other mental health conditions such as Anxiety, Obsessive-Compulsive Disorder and Post-traumatic stress disorder. SSRIs work best when used in conjunction with psychotherapy. SSRIs are generally the first line of medication, due to how they have fewer side effects than other types of antidepressants.





How do they work?: Unfortunately, it isn’t entirely known how SSRI antidepressants work. It is believed that SSRIs increase the level of serotonin in the brain – which is linked to mood, emotion and sleep. SSRIs block reuptake (absorption of nerve cells), allowing more serotonin to be available. When combined with psychotherapy, SSRIs can be particularly useful.


How effective are they?: Research on the efficacy of SSRI antidepressants is mixed. For moderate or severe depression, SSRIs have been shown to be particularly useful. However for mild cases, research is mixed. SSRIs aren’t better than other classes, but do offer fewer side effects.


Treatment Course: SSRI Antidepressants generally come in tablet form, though some can be injected or taken as a liquid if required. Once prescribed, a low dose will initially be prescribed. A typical treatment course lasts six months., though it can often rise to around 18 months, or even indefinite use. Unfortunately, it takes at least two weeks for benefits to be felt. At first, your mood may start to increase again. The full benefits of antidepressants normally take up to six weeks to be felt. If after this point you haven’t witnessed an improvement, it is worth talking to your GP or mental health specialist. They may suggest switching antidepressants. Many people succeed on their second antidepressant. It is highly likely you will experience some mild side effects early in the treatment. It is crucial however to not stop taking the tablets, as these side effects will disappear quickly. All SSRI antidepressants can be prescribed by a GP.


Types of SSRIs: There are seven SSRIs prescribed in the United Kingdom. Six are prescribed for mental health conditions, with Dapoxetine (Priligy) generally only prescribed for erectile dysfunction.



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Side Effects

We recommend consulting the individual page for each antidepressant for information on side effects – as they differ from tablet to tablet. Furthermore, the leaflet that comes with each pack of tablets contains enhanced information on side effects. Side effects generally are only present in the first few days of treatment, with the body needing time to get used to treatment. You will often see a GP during the first month of treatment to see how you are reacting.


People taking SSRIs will generally only experience mild side effects that don’t last too long. Common side effects include shakiness, headaches, anxiety, sickness, drowsiness, low sex drive and difficulty in achieving orgasm. The information leaflet with each medicine will include full instructions and information on the side effects. An overdose could induce serotonin syndrome, so should therefore be avoided.




As with any medication, you must be careful when taking SSRI antidepressants. Your GP or mental health professional should make you aware of any types of medicine or foods that you should avoid. Some frequently used medications, even over-the-counter ones shouldn’t be used with antidepressants. It is worth looking at the individual page of each antidepressant to see cautions, but an overview is provided here.


Other Medicines: Ibuprofen and aspirin are often not recommended when using SSRI antidepressants. Each information leaflet will provide the types of medicines not to be used. It is important NOT to combine medicines from different classes of antidepressants, or take two from one class at the same time. You should also avoid the herbal remedy St John’s Wort. The asthma medication Theophylline should be avoided. Clozapine and Pimozide should also be avoided.


Alcohol: Alcohol acts as a depressant, therefore it is recommended that anyone taking an antidepressant stays away from drinking alcohol.


Pregnancy and Breastfeeding: Antidepressants generally aren’t recommended for pregnant women. Taking antidepressants while breastfeeding also isn’t recommended.


Young People: People under the age of 18 are rarely prescribed antidepressants, instead being offered therapy. The exception to this is Fluoxetine (Prozac). If therapy hasn’t worked, antidepressants can be prescribed. People under the age of 25 taking antidepressants have been shown to be vulnerable to suicidal thoughts – a serious side effect.


Illicit Drugs: The use of illegal or recreational drugs isn’t recommended, as they can react unpredictably with antidepressants. Cannabis, cocaine, heroin and ketamine have been known to particularly worsen symptoms.


Bipolar Disorder: You shouldn’t take SSRI antidepressants as they can trigger a manic or psychotic episode.


As always, ensure you read the information leaflet.