Tyramine reaction

Background

  • Occurs when patient taking a monoamine oxidase inhibitor (MAO-I) ingests tyramine
    • Tyramine is a dietary amine similar to amphetamine normally metabolized by MAO
    • Tyramine is a monoamine and acts indirectly to release catecholamines.
    • Tyramine is typically metabolized by monoamine oxidase in the gut, a process that MAOIs interfere with.
    • Tyramine is found in preserved meat, fish, cheese, alcohol, and protein-rich foods which are particularly likely to contain bacteria that convert amino acids into monoamines like tyramine.

Clinical Features

  • Rapid onset (within 15-90 minutes of ingestion) of:
    • Severe occipital or temporal headache
    • Sympathomimetic effects: hypertension, diaphoresis, mydriasis, palpitations, chest pain
  • Syndrome usually resolves on own over 6 hours

Differential Diagnosis

Hypertension

Evaluation

  • ECG: monitor for cardiac ischemia
  • CT head: if patient has focal neurologic findings or persistent, severe headache

Management

  • Hypertensive emergency: phentolamine is agent of choice
    • 2.5-5mg IV q5-15min until blood pressure controlled
    • Duration of action <1 hour
  • Beta-blockers contraindicated

Disposition

  • Discharge home if asymptomatic after 4 hours of observation

References

Authors:

Ross Donaldson