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Hypersensitivity Reactions (Adult)

Hypersensitivity Reactions (Adult)

Notes

  • Approximately 20% of allergic reactions follow a biphasic course.
  • The mean time to the onset of second-phase of reactivity is believed to be 10 hours. This can vary in the literature from 1-8 hours to as long as 24-38 hours after the initial reaction.
  • Of those who have a second-phase reaction one-third will be more severe, one-third will be similar and one-third will be milder.
  • Corticosteroids may be of benefit in preventing second-phase reaction.
  • Some literature recommends that patients be given a minimum of 3-4 days of regularly dosed steroid and antihistamine post anaphylaxis

Select Severity

  • Urticaria
  • Hives
  • Pruritis

1 or more of the following:

  • Angioedema
  • Bronchospasm/wheezing/respiratory distress
  • Hemodynamic instability
  • With or without:
    • Urticaria
    • Hives
    • Pruritis

More Information

  • Updated June 2017
  • Minor revisions Dec 2018 and November 2020