Last reviewed: 20 Dec 2020
Last updated: 26 Jun 2020



History and exam

Key diagnostic factors

  • erythematous oedematous lesions
  • pruritus
  • resolution within 24 hours
  • swelling of face, tongue, or lips

Risk factors

  • positive family history
  • female sex
  • exposure to drug trigger
  • exposure to food trigger
  • recent viral infection
  • recent insect bite or sting

Diagnostic investigations

1st investigations to order

  • FBC with differential
  • erythrocyte sedimentation rate (ESR)
  • CRP
  • C4 level
More 1st investigations to order

Investigations to consider

  • thyroid-stimulating hormone (TSH)
  • antinuclear antibodies (ANA)
  • skin prick testing
  • allergen avoidance diet
  • serum tryptase
  • skin biopsy
  • C1 esterase inhibitor level
  • C1 esterase inhibitor function
  • C1q levels
  • specific IgE to suspected allergen
More investigations to consider

Treatment algorithm


Professor of Medicine

Department of Internal Medicine

Division of Immunology/Allergy Section

University of Cincinnati




JB is a consultant, contracted researcher, and speaker for Sanofi-Regeneron, AstraZeneca, Novartis/Regeneron, Shire/Takeda, CSL Behring, Pharming. He is also a consultant and contracted researcher for Allakos, Kalvista, Bioscryst, IONIS. JB is a member of the Joint Task Force practice parameter. JB has spoken on this topic at National, International and Regional/Local Educational meetings. JB is an author of abstracts and manuscripts related to these topics and is an author of a number of references cited in this topic.

Dr Jonathan Bernstein would like to gratefully acknowledge Dr S. Shahzad Mustafa and Dr Stephen Dreskin, previous contributors to this topic.


SM is on the speakers' panel and advisory board for Genentech. SD declares that he has no competing interests.

Peer reviewersVIEW ALL

Consultant Dermatologist

Warwick Hospital

Honorary Associate Professor

University of Warwick

Warwick Hospital




FH has attended educational events organised and funded by Almrall and Schering Plough; has received a speaker's fee from Steibel, Leo, and Schering Plough; and is an author of references cited in this topic.

Consultant in Dermatology

University Hospital of South Manchester




None declared.

Head of Allergy and Training Program Director

Winthrop University Hospital

Associate Professor of Clinical Medicine

SUNY at Stony Brook

Stony Brook



LF declares that she has no competing interests.

Use of this content is subject to our disclaimer