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Selective Serotonin Reuptake Inhibitors (SSRI)

4.3. Psychiatric adverse effects

Councillor with a patient Very common and common adverse effects

SSRIs can produce an uncomfortable mental sensation of tension, restlessness or anxiety (akathisia—feeling of restlessness and inability to sit or stand still). This paradoxical state of anxiety can occur when initiating treatment. Severe agitation, psychotic symptoms and suicidal ideation are rare but these serious symptoms must be recognised and addressed.

Factors which increase risk

Patients already predisposed to anxiety or panic disorder may be at higher risk of SSRI-related agitation and anxiety symptoms.

Risk-reduction measures

Before commencing SSRI therapy, a thorough patient history should elicit previous anxiety and panic symptoms, and previous (or family) history of SSRI-induced agitation or anxiety. Patients should be advised that the medicine could make them feel more anxious initially and that this should settle within a few days.


Anxiety symptoms often settle within a few days of treatment. Regular review and reassurance of the patient may be all that is required. If anxiety symptoms do not abate, the dose of SSRI may have to be reduced. For severe and distressing symptoms use of a benzodiazepine1 early in the treatment may be considered but, to reduce the risk of benzodiazepine dependence2, the duration of such treatment should not exceed two weeks. If symptoms persist, an alternative treatment should be considered.

  1. Class of medicines which have a sedating effect, most often used for anxiety and insomnia, but also used for muscle relaxation, managing convulsions, and as premedication for surgery and certain procedures. The class includes: chlordiazepoxide, diazepam, flurazepam, lorazepam, midazolam, nitrazepam, oxazepam, and tempazepam.
  2. Compulsive or chronic need for a chemical substance (eg alcohol, benzodiazepine, or opioid).