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Insect bites and stings

Last reviewed: 30 Oct 2023
Last updated: 27 Apr 2021



History and exam

Key diagnostic factors

  • witnessed bite/sting
  • local edema
  • local pain
  • local warmth
  • local markings
  • pruritus
  • wheal and flare
  • skin pallor
  • clamminess
  • signs of airway compromise
  • oropharyngeal edema
  • dyspnea
  • rales/crackles/wheeze
  • tachycardia
  • irregular pulse
  • skin flushing
  • altered alertness
More key diagnostic factors

Other diagnostic factors

  • pustules
  • bulls-eye-shaped rash
  • rash on palms and soles
  • linear raised rash
  • hypertension
  • fever
  • muscle cramp
  • diaphoresis
  • tremor
  • paresthesia and/or fasciculations
  • generalized pain
  • nausea/vomiting
  • headache
  • abdominal pain
  • history of immunocompromised state
  • history of cardiovascular disease
  • abscess
  • necrosis
  • cough
  • hypotension
  • arthralgia
  • adenopathy
Other diagnostic factors

Risk factors

  • occupational or recreational exposure to insects
  • geographic exposure to insects
  • previous history of anaphylactic (or anaphylactoid) response
More risk factors

Diagnostic investigations

1st investigations to order

  • clinical diagnosis
More 1st investigations to order

Investigations to consider

  • CBC
  • serum tryptase
  • sensitivity testing
More investigations to consider

Treatment algorithm


anaphylaxis/anaphylactoid reaction


local reaction


secondary infection: immunocompetent; low MRSA risk



Tom Morrissey, MD, PhD
Tom Morrissey

Associate Professor

Department of Emergency Medicine

University of Florida




TM declares that he has no competing interests.


Tom Morrissey would like to gratefully acknowledge the assistance of Richard Vetter (MS) from the Department of Urban Entomology at the University of California.


Not disclosed.

Peer reviewers

Theodore M. Freeman, MD

Allergist and Immunologist

Jacobs Ramirez and Freeman Allergy & Immunology

San Antonio



TMF is an author of a number of references cited in this topic.

Andrew Parfitt, MBBS, FFAEM

Clinical Director

Acute Medicine

Associate Medical Director

Consultant Emergency Medicine

Guy's and St Thomas' NHS Foundation Trust

Clinical Lead and Consultant

Accident Emergency Medicine

St Thomas' Hospital




AP declares that he has no competing interests.

Richard DeShazo, MD

Chairman and Professor

Department of Medicine

Professor of Pediatrics

Billy S. Guyton Distinguished Professor

University of Mississippi Medical Center




RD is an author of a reference cited in this topic.

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