MHRA LogoHome

Selective Serotonin Reuptake Inhibitors (SSRI)

5. Key points

Checklist By working through this module, you will have acquired an understanding of the principal risks of SSRIs and how the risks can be managed. The following is a quick reminder of the important points covered:

  • SSRIs are licensed for depressive illness. Some are also licensed for other indications including anxiety disorders, obsessive–compulsive disorder and bulimia nervosa
  • Clinical response to SSRIs usually occurs within two weeks, maximal response usually within four to six weeks
  • Adverse effects of SSRIs such as headache, nausea, and anxiety/agitation are very common at the start of treatment; these effects often resolve spontaneously. Withdrawal reactions also occur frequently
  • Sexual side effects occur frequently but may not be volunteered by the patient
  • Rare but life-threatening adverse effects include serotonin syndrome (medical emergency), haemorrhage, convulsions, hyponatraemia and psychiatric disorders (mania1, suicide risk)
  • Important drug interactions include serotonergic2 agents (especially MAOIs3, linezolid, ‘triptan’ antimigraine drugs, tramadol), antiplatelet4 drugs, anticoagulants, and NSAIDs
  • As with other antidepressants the activating effects of SSRIs may lead to an increase in motivation before any mood-lifting effects occur, so close attention to suicide risk is advised especially in the early weeks of treatment
  • SSRIs are generally safer in overdose than other classes of antidepressant medicine.

  1. A persistent mood elevation out of keeping with the individual’s circumstances, characterised by symptoms such as excitement, irritability, loss of need for sleep, grandiosity and loss of inhibition. The symptoms are extreme and the individual may not be able to control them. Delusions or hallucinations may be present.
  2. A chemical agent (or synapse) that produces its effects via the serotonin transmitter system.
  3. Monoamine oxidase inhibitors act within nerve cells to block the enzyme that promotes breakdown of the monoamine neurotransmitters, noradrenaline and serotonin. Therefore, nerve endings can release more neurotransmitter at the synapse. Examples of MAOI antidepressants include isocarboxazid, phenelzine, and tranylcypromine. The antidepressant, moclobemide, is a reversible inhibitor of monoamine oxidase type A (RIMA).
  4. Antiplatelet medicines are used to prevent heart attacks and strokes. They prevent platelets from clumping together, which, in turn, helps to prevent the formation of clots. Antiplatelet medicines include aspirin, clopidogrel, dipyridamole, and prasugrel.