By Dr Ananya Mandal, MD
Selective serotonin reuptake inhibitors (SSRIs) are a class of antidepressants that are used in the treatment of clinical depression. These agents are also useful in several other mental health conditions such as anxiety disorder, obsessive compulsive disorder, panic disorder and some phobias such as social phobia and agoraphobia (fear of open spaces).
Examples of SSRIs
Some examples of commonly used SSRIs include:
- Fluoxetine (prozac)
Mechanism of action
SSRIs increase the serotonin level in the brain by preventing it's reuptake by the presynaptic neurons, meaning the hormone instead remains available to bind to postsynaptic neurons and exert its mood enhancing effects. Many experts believe that low serotonin levels are a cause depression.
Increased serotonin levels due to SSRI therapy has proved beneficial in the treatment of individuals with depression. SSRIs are currently the mainstay of treatment for depression and are preferred over other classes of medications such as tricyclic antidepressants and monoamine-oxidase inhibitors because they are more effective and cause fewer side effects.
Side effects of SSRIs
Some of the side effects of SSRIs include:
- Increase in suicidal thoughts and behaviors.
- Anxiety, restlessness, agitation, aggressiveness and hostility
- Sudden cessation of SSRIs can cause withdrawal syndrome
- Nausea, vomiting, weight gain or loss, dry mouth, diarrhea and constipation
- Loss of sleep or insomnia
- Excessive sweating
- Blurred vision
- Loss of libido and erectile dysfunction
With time, many of the less serious side effects of SSRI therapy may improve. Those under the age of 25 years are more at risk of suicidal thoughts and self-harm behaviors with the use of SSRIs than other age group and this is an important side effect to look out for in young people with depression.
Usually, the lowest dose of the drug is prescribed at first. The dose may be gradually increased over time as side effects begin to improve. SSRIs start to take effect at around two to four weeks, when a patient starts to feel an improvement in their mood.
SSRIs must not be prescribed in the presence of certain other conditions such as pregnancy (unless the benefits outweigh the risks), kidney dysfunction or glaucoma.
Reviewed by Sally Robertson, BSc
Last Updated: Oct 8, 2014