Atypical Antidepressants refer to a group of Antidepressants that can be used in the treatment of many mental health conditions.

The various antidepressants in this group do not fit into any of the other classes of antidepressants, and are thus classed as “Atypical”.

Despite their name, they are widely-used, effective, and are often combined with other antidepressants in the case of poor response to either a Selective Serotonin Reuptake Inhibitors (SSRIs) or Serotonin and Norepinephrine Reuptake Inhibitors (SNRIs).

Atypical Antidepressants work best when combined with a form of talking therapy.

A few different medicines make up the Atypical antidepressant class

Information on Atypical Antidepressants

It often takes between four and six weeks for the full effect of any antidepressant 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. Even when the patient feels better, it is important to continue to take an antidepressant, as this will improve the chances of symptoms not coming back.

Many people will take an antidepressant for a few months, but it is often longer. Everyone has a unique situation.

What conditions are Atypical Antidepressants used for?

Atypical antidepressants can feasibly be used in the treatment of a range of conditions. They are often used as an add-on medicine which is used alongside another medication.

Among the conditions that atypical antidepressants can treat include:

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

What are the different types of Atypical Antidepressants?

There are numerous antidepressants that are considered to be “Atypical”. These are medicines that for whatever reason do not fit into any of the main classes of antidepressants.

Five medicines that are licensed for use in the United Kingdom for mental health conditions make up this class. Other off-label atypical antidepressants could also fit into this class.

  • Mirtazapine (Remeron)
  • Trazodone (Molipaxin)
  • Agomelatine (Valdoxan)
  • Mianserin (Tolvon)
  • Reboxetine (Edronax)

How do Atypical Antidepressants work?

One of the main reasons why the medicines in this group do not belong to any other type of antidepressant class is due to their different mechanism of action.

Each antidepressant in this class has a different approach. In general, antidepressants are believed to work by increasing levels of a group of chemicals in the brain called neurotransmitters.

Atypical antidepressants range in their method of action, but the neurotransmitters targeted include serotonin, norepinephrine and dopamine. These are chemicals that appear to be linked to mood. However, it isn’t known how this process entirely works.

Due to their different mechanism of action, these medicines are commonly used as an add-on medicine when patients have not found an SSRI or SNRI beneficial.

Side Effects of Atypical Antidepressants

Like all antidepressants, side effects are common with Atypical antidepressants. But, when compared to older antidepressants, atypical antidepressants have rather mild side effects.

Each medicine within this class has a different side effect profile. With any antidepressant, a Patient Information Leaflet will be included in the box. This leaflet provides an exhaustive list of side effects.

Side effects from Atypical antidepressants can cause some discomfort initially, but shouldn’t last too long. Sometimes, side effects will last just a few days as the body adjusts to the medication. However, some side effects may be persistent.  

Common side effects of Atypical antidepressants include dry mouth, dizziness, constipation and light-headedness. Unlike the majority of other antidepressants, many atypical antidepressants do not cause 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 occurs, it is important to contact a Doctor or emergency department immediately. 

In the event of the side effects impacting a patient negatively, it is always possible to change antidepressant. However, any such change should only ever be done under the supervision of a doctor.

Cautions of Atypical Antidepressants

It is crucial to thoroughly read the Patient Information Leaflet that comes with any medication. The leaflet will include specific cautions that should be taken into consideration when taking the medicine.

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.


Atypical antidepressants are an interesting range of medicines. Due to their rather ambiguois position, they often aren’t chosen as a first-line medicine.

However, they have helped many patients to see an improvement in their mental health. This is particularly the case when they are used as an add-on medicine.

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] Leslie, L. K., Newman, T. B., Chesney, P. J., & Perrin, J. M. (2006). The Food and Drug Administration’s Deliberations on Antidepressant Use in Pediatric Patients. Pediatrics. 116 (1): p195-204. DOI: