Serotonin Syndrome

Serotonin syndrome is a serious and life-threatening reaction caused by excess serotonin in the CNS.

The classic triad

  1. Mental status changes (anxiety, restlessness, delirium, easy to startle)
  2. Autonomic hyperactivity (hyperthermia, hypertension, tachycardia, diaphoresis, vomiting, diarrhea)
  3. Neuromuscular abnormalities (hyperreflexia, myoclonus, tremor, muscle rigidity, and bilateral Babinski sign) – more pronounced in lower extremities
Serotonin Syndrome Neuroleptic Malignant Syndrome
Onset <24 H Days to weeks (not
Neuromuscular Hyperreactivity (tremor, clonus) Severe muscle rigidity, hyporeactivity (bradyreflexia)
Cause SSRIs, TCAs, MAOIs, other serotonergic drugs Dopamine antagonists (antipsychotics)
Lab findings None Elevated CK
Treatment STOP AGENT! Benzodiazepines +/- Propranolol STOP AGENT! + Bromocriptine +/- Dantrolene
Resolution Within 24h Days to week



Bipolar I, II, and Cyclothymia

First thing’s first, it is important to understand the difference between a mood episode and a mood disorder.

Mood Episodes

The best way is to think of the episodes as the building blocks of the disorders.

Major Depressive Episode: 2 week period of depressed mood OR anhedonia plus 4 other symptoms of MSIGECAPS (useful mnemonic)

  • Mood (low)
  • Sleep (decreased)
  • Interest (decreased)
  • Guilt
  • Energy (low)
  • Concentration (poor)
  • Appetite (decreased)
  • Psychomotor retardation or agitation
  • Suicidal ideation

Manic Episode: 1 week period of elevated or irritable mood with 4 or more of (mnemonic  GST PAID)

  • Grandiose thoughts
  • Sleep, decreased need for
  • Talkative
  • Pleasurable activities with Painful consequences (gambling, spending lots of money, having lots of sex)
  • Activity increased
  • Ideas (flight of)
  • Distractability

Hypomanic Episode: Same as manic except dialled down a notch. Only needs to be 4 days with 3 or more symptoms. People can still function and generally like being hypomanic, but their friends and family will notice a difference in them.

Mixed Episode: BOTH manic episode and major depressive episode at the same time (as in during the same day they’ll experience both depression and mania) in 1 week.

Mood Disorders

Bipolar I

  • 1 manic episode OR 1 mixed episode
  • Treatment: mood stabilizer (lithium or anti-convulsant), consider adding atypical antipsychotic (quetiapine, clozapine, olanzapine)
  • Carbamazepine, valproic acid, and lamotrigine do not have good antidepressant effects, they’re only antimanic
  • Tegretol (carbamazepine) not used much because rush of Steven-Johnson’s syndrome, CP450 interactions and neutropenia

Bipolar II

  • MDE + hypomanic episode
  • NO manic or mixed episodes
  • Treatment: lithium, consider adding atypical antipsychotic


  • >2 years, never without symptoms for >2 months.
  • Hypomanic + Depressive Symptoms (not meeting the criteria for MDE)
  • Treatment: lithium, anticonvulsants (divalproex, lamotrigine)