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Anaphylaxis: Understanding Allergic Emergencies



Overview

Anaphylaxis (pronounced ana-fill-axis) is a potentially life-threatening allergic reaction that occurs when your immune system over-reacts to an allergen. An allergic reaction happens when your immune system wrongly identifies a substance (e.g. a food) as a threat and releases chemicals, such as histamine, that cause the symptoms of an allergy (e.g. sneezing or watery eyes).


These allergy symptoms usually aren't life-threatening, but a severe reaction can lead to anaphylaxis. This is when a surge of these chemicals can cause your body to go into shock: blood pressure drops and your airways can narrow, creating breathing difficulties among other serious symptoms.


Anaphylactic shock is relatively common, with one in 20 Americans and 50% of adults with food allergies having experienced anaphylaxis . This reaction can occur very quickly (within minutes) and requires immediate emergency treatment. Without rapid treatment, anaphylaxis can be fatal, making it vital to understand the common causes and symptoms of anaphylaxis.



What triggers anaphylaxis?

Common allergens and triggers of anaphylaxis include:

  • Food such as peanuts or tree nuts, hen's eggs, shellfish, cow's milk, and sesame seeds

  • Insect stings such as wasp and bee stings

  • Medicines such as antibiotics and non-steroidal anti-inflammatory drugs (NSAIDs)

  • Anaesthesia

  • Latex (a type of rubber commonly found in rubber gloves and condoms)

Anaphylaxis can less commonly be exercise-induced in some individuals, meaning that aerobic activity like running or even walking can cause an attack. This can be triggered if you exercise on its own, or it might be that exercising after exposure to a common allergen triggers the attack.


Sometimes the trigger of an attack is unknown (idiopathic anaphylaxis). Your healthcare provider might run some tests to help identify the allergen, but is may remain unidentified.



What are the signs and symptoms of anaphylaxis?

Symptoms of anaphylaxis typically present within minutes of coming into contact with the allergen and rapidly worsen, making it important to act quickly. Common symptoms include:

  • Swelling or tightness of your throat and tongue

  • Breathing difficulties, such as coughing and wheezing, or taking rapid shallow breaths

  • Blue-grey, pale or clammy skin

  • Feeling faint or dizzy

  • Feeling tired, confused or anxious

This can easily be remembered as the 'ABC' symptoms for Airway, Breathing, and Consciousness/Circulation.


Other symptoms may include an itchy raised rash (hives) anywhere on the body, a tingling or itchy feeling in the mouth, and stomach pain or vomiting. These symptoms might occur alongside the ABC symptoms, or may be present on their own. If you don't have the ABC symptoms the reaction might not be as serious as anaphylaxis, but it is still important to seek medical attention and watch for development of the ABCs.


Although most reactions occur rapidly, it is important to note that anaphylaxis can sometimes be delayed until two to three hours after exposure to the allergen.



What to do if you have an anaphylactic shock?

If you think think you or someone else is having an anaphylactic reaction it is important to act quickly:

  • Use an adrenaline auto-injector (e.g. an EpiPen) if you have one - the instructions can be found on the side. If the symptoms haven't improved within 5 minutes, use a second one if available.

  • Dial 911 immediately for an ambulance and explain to the emergency services that you think you are having an anaphylactic reaction.

  • Lie down and raise your legs. If you are struggling to breathe, you can raise your shoulders or sit up slowly, but it is important not to stand up or walk around even if you feel better as this can cause your blood pressure to drop.

  • Remove the trigger if possible. For example, if a bee sting triggered the reaction, remove the sting. However, do delay other treatment if removing the trigger is not possible. It is not recommended to attempt to make a person vomit if the anaphylaxis was food-induced.

  • If the person if unresponsive and not breathing normally, cardiopulmonary resuscitation (CPR) should be started immediately and ensure that help us on the way.

When you are taken to hospital, immediate treatment will be given. Treatment may include administration of adrenaline to open airways and raise blood pressure, oxygen therapy to help breathing, and intravenous fluids to increase blood pressure and restore fluids.


After an anaphylactic reaction, a person will typically stay in hospital for 2-12 hours, although a longer stay may be required. Before leaving, you should be referred to a specialist allergy service to investigate the suspected anaphylaxis further and provide a diagnosis if appropriate.



How is anaphylaxis diagnosed?

To help diagnose anaphylaxis or a severe allergy, your healthcare provider might take your medical history and ask about any known previous allergic reactions.


To confirm a diagnosis, some further tests might be used:

  • Allergy tests: Skin or blood tests can be used to help determine your trigger by testing for a reaction to different allergens.

  • Tryptase test: A blood test can be used up to test for the presence of tryptase - one of the chemicals released into your blood during an anaphylactic reaction - up to three hours after a reaction.

If you are diagnosed with a serious allergy or are at a risk of anaphylaxis, you and your healthcare provider should develop an allergy action plan. This can help you and those around you recognise if you are having a reaction and know what to do in an emergency.


You should also be prescribed an adrenaline auto-injector (AAI) which can be used to deliver adrenaline in case of a severe reaction. You should always carry two in-date AAIs with you in case one fails or you need a second dose - this can save your life.



Summary

Anaphylaxis is a severe and life-threatening allergic reaction that is caused by exposure to an allergen, such as food, insect stings, or medication. Symptoms include swelling of the airway, breathing difficulties, and unconsciousness or confusion, and require immediate medical attention. Recognizing the triggers and symptoms of anaphylaxis is crucial for early treatment and intervention which can save lives. If you or someone you know is at risk of anaphylaxis, it's essential to consult with a healthcare provider and develop an action plan for dealing with potential allergenic exposures. Anaphylaxis is a serious condition, but with knowledge and preparedness, we can mitigate its impact and protect those at risk.


Sources

Assessed and Endorsed by the MedReport Medical Review Board




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