First aid

16 January 2015

Symptoms of anaphylaxis

Anaphylaxis is a reaction that can affect the entire body and therefore has a number of symptoms. It is important to watch for these symptoms in a person with severe allergies and seek treatment as quickly as possible if any occur.


Anaphylaxis is a systemic reaction, which means that many parts of the body are affected.

The time lapse between ingestion/or contact with the allergen and anaphylactic symptoms varies among individuals. Symptoms can appear immediately or can be delayed from 30 minutes to one hour after exposure. Symptoms may also disappear and then recur hours later. Once symptoms arise, they progress quickly.

Symptoms of anaphylaxis can vary from mild to severe and are potentially deadly. The most dangerous symptoms are low blood pressure, breathing difficulties, shock and loss of consciousness, all of which can be fatal.

Cardiovascular: Reported symptoms include, hypotension, chest pain or tightness, cardiac arrest, faint pulse and shock.

Dermatologic: Reported symptoms include, urticaria, swelling, itchy skin, sensation of warmth, reddening of the skin, flushing, angioedema and rash.

Gastrointestinal: Nausea, pain/cramps, vomiting, diarrhea, itchy mouth/throat.

Pulmonary: Histamine can induce vasodilatation of arterioles and constriction of bronchioles in the lungs, also known as bronchospasm. Other symptoms may include respiratory distress, throat tightness, hoarse voice, cough, nasal congestion, trouble swallowing, fainting, light-headedness, unconsciousness, angioedema, wheezing, respiratory arrest and death.

Other: Other possible symptoms include anxiety, hay fever-like symptoms, red/itchy/watery eyes, headache and cramping of the uterus.

This information has been edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (

  • American Academy of Allergy Asthma & Immunology. Anaphylaxis.
  • MedlinePlus. Anaphylaxis.
  • Natural Standard: The Authority on Integrative Medicine. Copyright © 2008.
  • Neugut AL, Ghatak AT, Miller RL. Anaphylaxis in the United States: An investigation into its epidemiology. Archives of Internal Medicine 61 (1): 15-21. 2001.
  • Sussman GL, Beezhold DH. Allergy to latex rubber. Annals of Internal Medicine 122 (1): 43-6. 1995.
  • The Food Allergy & Anaphylaxis Network.
  • Valentine, M.D. Anaphylaxis and Stinging Insect Hypersensitivity. Journal of the American Medical Association. (1992) 268:2830-2833.


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