What is Anaphylaxis? The nitty-gritty - Lifelab Testing

What is Anaphylaxis? The nitty-gritty

Last Updated: 10th November 2022 · Written by Kate Young

What is it?

Anaphylaxis (also known as ‘anaphylactic shock’ or ‘anaphylaxia’) is a severe allergic reaction that affects the patient’s airways, heart, circulation, gut, and skin. The reaction usually occurs within minutes of exposure to the triggering allergen but can begin up to 2 or even 3 hours after initial contact. This reaction is potentially life-threatening and should be treated immediately by a medical professional.

Signs and Symptoms of Anaphylaxis

As anaphylaxis affects various systems within the body, there are many signs and symptoms of the reaction.

  • Trouble swallowing
  • Wheezing and a tight test
  • Nausea, abdominal pain, and vomiting
  • Diarrhoea
  • Feeling weak and floppy
  • Swelling of the lips, throat or anywhere on the body
  • Collapsing and/or passing out         
  • Flushed skin (this may be widespread)
  • Sudden drop in blood pressure
  • Itchy rash (or hives)

Causes of Anaphylaxis

Anaphylaxis is almost exclusively caused by an allergy, with the vast majority of cases being triggered by one of the 14 major allergens;

  • celery
  • cereals containing gluten – including wheat, rye, barley and oats
  • crustaceans – such as prawns, crabs and lobsters
  • eggs
  • fish
  • lupin
  • milk
  • molluscs – such as mussels and oysters
  • mustard
  • tree nuts – including almonds, hazelnuts, walnuts, brazil nuts, cashews, pecans, pistachios and macadamia nuts
  • peanuts
  • sesame seeds
  • soybeans
  • sulphur dioxide and sulphites (if they are at a concentration of more than ten parts per million)

Having an allergy to any of these major allergens increases the risk of anaphylaxis. The incidence of anaphylaxis appears to be increasing in the UK. Between 1992 and 2012, the number of yearly hospital admissions tracked by the NHS increased by over 600%, from approximately 1,150 admissions to over 8,200 [1]. The trend seems to be continuing, with admission for under 18’s Between 2014 and 2019 has risen by a staggering 70% [2].

Treatment and Outlook

If you are experiencing a bout of anaphylaxis, it is important to act fast. The first course of action is to administer adrenaline. Pre-loaded auto-injectors containing adrenaline are prescribed to individuals at high risk of anaphylaxis. These auto-injectors should be available at all times – no exceptions.

Adrenaline is crucial in these first few minutes as it acts to rapidly open up the patient’s airways, get their blood pressure back up and stop any swelling. If you suspect that you’re experiencing anaphylaxis but aren’t certain, it is recommended that adrenaline is administered anyway – as it’s better to be safe than sorry.

Following administering adrenaline, an ambulance should be called immediately, even if the person’s condition improves upon injecting adrenaline. If their condition gets worse after making that initial 999 call, call them again to ensure an ambulance is dispatched, as you will be put on a higher priority. 5-10 minutes after the first adrenaline injection, a second shot should be administered if the symptoms of anaphylaxis remain. 

Remember, anaphylaxis always requires an immediate emergency response. In the US, an estimated in the US, an estimated, 1% of hospitalisations due to anaphylaxis have a fatal outcome [3], so medical attention is vital.

Risk Factors

There are several risk factors associated with anaphylaxis that can be partly controlled or seen as times, to take extra precautionary measures. These include;

  • Poorly controlled asthma
  • Current or recent infection
  • Exercise prior to or shortly after contact with the allergen
  • Suffering from hay fever or other aeroallergen symptoms
  • Emotional stress
  • Drinking alcohol

Research has also highlighted a few other risk factors to be aware of. For example, this study found that as a patient’s age increases, their risk of developing severe cardiovascular symptoms increases substantially [4].  

Suffering from a pre-existing respiratory illness can also be a factor, as studies have shown that poor management of allergic bronchial asthma drastically increases the risk of severe anaphylaxis [5]

Lastly, it appears that male patients are more likely to develop anaphylaxis from insect venom compared to females [6]. This has been observed in both male adults and children.


The best way to prevent anaphylaxis is to be aware of your allergies and be mindful to avoid them wherever possible. Many people are unaware of any allergies they may have, and most health professionals don’t carry out routine testing without prior evidence of an existing allergy or a family history.

Some people may feel that this is something they want to take into their own hands and opt for allergy testing to ensure they don’t remain ignorant of any potential allergies they may have.  

Final Thoughts

While the number of yearly deaths from anaphylaxis is relatively small, it still concerns us to know we may be at risk of anaphylaxis. And it’s far from an enjoyable experience either way. This life-threatening condition can be avoided with diligence and the knowledge of what your body may react adversely to.


[1] Turner, P.J., Gowland, M.H., Sharma, V., Ierodiakonou, D., Harper, N., Garcez, T., Pumphrey, R. and Boyle, R.J. (2015). Increase in anaphylaxis-related hospitalizations but no increase in fatalities: An analysis of United Kingdom national anaphylaxis data, 1992-2012. Journal of Allergy and Clinical Immunology, 135(4), pp.956-963.e1. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4382330/ [Accessed 2 Mar. 2020].

[2] NHS Digital. (2018). Hospital admissions for allergies and anaphylactic shock – NHS Digital. [online] Available at: https://digital.nhs.uk/data-and-information/find-data-and-publications/supplementary-information/2018-supplementary-information-files/hospital-admissions-for-allergies-and-anaphylactic-shock [Accessed 2 Mar. 2020].

[3] Ma, L., Danoff, T.M. and Borish, L. (2014). Case fatality and population mortality associated with anaphylaxis in the United States. Journal of Allergy and Clinical Immunology, [online] 133(4), pp.1075–1083. Available at: https://www.sciencedirect.com/science/article/abs/pii/S0091674913016424 [Accessed 2 Mar. 2020].

[4] Worm, M., Babina, M. and Hompes, S. (2013). Causes and risk factors for anaphylaxis. Journal der Deutschen Dermatologischen Gesellschaft = Journal of the German Society of Dermatology : JDDG, [online] 11(1), pp.44–50. Available at: https://www.ncbi.nlm.nih.gov/pubmed/23181736 [Accessed 2 Mar. 2020].

[5] Iribarren, C., Tolstykh, I.V., Miller, M.K. and Eisner, M.D. (2010). Asthma and the prospective risk of anaphylactic shock and other allergy diagnoses in a large integrated health care delivery system. Annals of allergy, asthma & immunology : official publication of the American College of Allergy, Asthma, & Immunology, [online] 104(5), pp.371–7. Available at: https://www.ncbi.nlm.nih.gov/pubmed/20486326?dopt=Abstract [Accessed 2 Mar. 2020].

[6] Ruëff, F., et al. (2009). Predictors of severe systemic anaphylactic reactions in patients with Hymenoptera venom allergy: importance of baseline serum tryptase-a study of the European Academy of Allergology and Clinical Immunology Interest Group on Insect Venom Hypersensitivity. The Journal of allergy and clinical immunology, [online] 124(5), pp.1047–54. Available at: https://www.ncbi.nlm.nih.gov/pubmed/19895993?dopt=Abstract [Accessed 2 Mar. 2020].

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