Selective Serotonin Reuptake Inhibitors (SSRIs) are a class of Antidepressants that are used to treat many different mental health conditions, such as Depression and Anxiety.

SSRI antidepressants are by far the most widely-used class of antidepressants – and form the first line of treatment for many conditions.

SRIs are most effective when used in conjunction with some form of talking therapy.

SSRI antidepressants are the most used class of antidepressants

Information on SSRI Antidepressants

It normally takes between four and six weeks for an antidepressant’s full effectiveness to be felt. However, minor improvements may be visible after around a week.

It is important to take an antidepressant how and when a Doctor has advised. This involves taking the correct dose at the right time, and taking the medication on a consistent basis. Never take more than one dose at a time to make up for a forgotten dose.

A low dose will initially be prescribed. Once remission has been achieved, it is important to continue to take an antidepressant, as this will improve the chances of symptoms not coming back.

Many people take antidepressants for a few months, or even years. Sometimes, antidepressant use can last for lifetime. There is no one-size fits all approach.

What conditions are SSRI Antidepressants used for?

SSRI antidepressants are typically used for a variety of conditions, including:

  • Depression
  • Anxiety
  • Post-Traumatic Stress Disorder
  • Obsessive-Compulsive Disorder
  • Eating Disorders
  • Personality Disorders
  • Dissociative Disorder
  • Somatic Disorders

What are the different types of SSRI Antidepressants?

There are seven different SSRI antidepressants that are licensed for use in the United Kingdom for mental health conditions.

Other SSRIs exist, but these are either not licensed in the United Kingdom, or are used for other purposes.

  • Fluoxetine (Prozac)
  • Citalopram (Cipramil)
  • Sertraline (Zoloft)
  • Paroxetine (Paxil)
  • Escitalopram (Cipralex)
  • Fluvoxamine (Faverin)
  • Vortioxetine (Brintellix)

How do SSRI Antidepressants work?

It isn’t entirely known how SSRI antidepressants work. It is believed that antidepressants in general work by increasing levels of a group of chemicals in the brain called neurotransmitters.

SSRIs work on the neurotransmitter serotonin – a chemical that appears to be linked to mood. How the exact process works isn’t known.

Side Effects of SSRI Antidepressants

Side effects are common with SSRI antidepressants. But, compared to other classes of antidepressants, SSRI antidepressants generally have milder side effects.

It is important to note that the side effects for each medicine within this class differs slightly. With any antidepressant, a Patient Information Leaflet will be included in the box. This leaflet provides an exhaustive list of side effects.

As mentioned, side effects from SSRI antidepressants are normally rather mild, and should only last for a few days as the body gets used to the medication. Some side effects, such as dry mouth or increased appetite, may be persistent.

Common side effects of SSRI antidepressants include headaches, sickness, drowsiness, increased/decreased appetite, dry mouth, weight gain, low sex drive and sexual dysfunction.

Serious side effects include suicidal thoughts, seizures, chest pain, psychosis or any abnormal behaviour. An overdose should be avoided, as it can cause the potentially fatal Serotonin Syndrome.

If any serious side effect appears, it is important to contact a Doctor or emergency department immediately. 

If side effects from antidepressants persist for a few weeks, or provide discomfort, it may be worth switching medication to an alternative antidepressant – although this should be done in conjunction with a Doctor.

Cautions of SSRI Antidepressants

It is important to thoroughly read the Patient Information Leaflet that comes with your medication. The leaflet will include specific cautions that should be taken into consideration when taking an antidepressant.

General considerations when taking antidepressants include:

  • Making the prescribing health professional aware of the use of any other medicine or substance – such as Herbal Remedies like St. John’s Wort.
  • Avoiding alcohol in the first few days of treatment, to allow the body to get used to the medication. After adjustment is complete, it is advised to not consume alcohol – given its properties as a depressant. If consumed, drinking alcohol in moderation is important.
  • Any antidepressant can react unpredictably with illegal drugs; therefore it is advisable to not use recreational drugs when undergoing antidepressant therapy.
  • Studies show that people under the age of 25 taking antidepressants are at heightened risk of suicidal ideation [1]. Therefore, it is important to exert caution during treatment.
  • Antidepressants shouldn’t routinely be taken during pregnancy or breastfeeding. It is important to discuss this with a Doctor.


SSRI antidepressants have helped a range of people to see an improvement in their mental health. They are capable of helping to treat a huge range of conditions.

However, there are many other classes of antidepressants, so if a person struggles to find an SSRI that works for them, there are other options available.

See Also



This website should be used purely for informational purposes, and does not intend to, nor should it ever, be used as a replacement for professional medical advice.

We strive to keep all of our pages updated, and ensure that our website is full of factual and in-depth information. However, we encourage you to browse this website with care.

As a reminder, this website and all content within it cannot and should not replace the advice of a trained medical professional. You can read our full disclaimer at this link.


If you are struggling with your mental health, help is available. With the right support and treatment, you can make a recovery. For information on helplines, or if you are in a state of crisis, please visit our crisis page by clicking on the relevant link for your geographical location (United Kingdom), (United States), (International). You can also see how to get mental health treatment and the process involved by clicking this link.


[1] Lagerberg, Y., Fazel, S., Sjolander, A., Hellner, C., Lichtenstein, P., & Chang, Z. (2021). Selective serotonin reuptake inhibitors and suicidal behaviour: a population-based cohort study. Neuropsychopharmacology. 47: p817-823. DOI: