The action of SSRIs goes beyond blocking 5HT reuptake. Recall that there are several subtypes of 5HT receptors with different functions. Although each agent has it’s own side effect profile there are some common side effects which can be expected based on the physiologic roles of serotonin throughout the body. The three areas listed below form the most common side effects.

SSRIs Adverse effects
CNS Gastrointestinal Sexual
Headache Diarrhea Anorgasmia
Mild stimulation(occasionally
aggitation)*
Dattime
Drowsiness and insomnia* Nausea Reduced libido*
Fatigue*
Anxiety*
Tremor Vomitting Abnornmal ejaculation or orgasm
Myolonus
Anorexia

* identifies the side effects which may interfere with monitoring a depressive syndrome.

In excessive doses SSRI’s or when a second serotonergic agent is added a central serotonin syndrome may develop. In some cases such as when an MAOI is given along with the SSRI the effect may be fatal. Below is a list of the signs/symptoms of the central serotonin syndrome.

Central Serotonin Syndrome

    Central Serotonin Syndrome

  • Hyperthermia;
  • Diaphoresis;
  • Gastrointestinal distress;
  • Mental Status changes;
  • Myoclonus