The Anaphylaxis Campaign is the only UK wide charity solely focused on supporting people at risk of severe allergic reactions. Anaphylaxis (pronounced ana-fill-ax-is) is a severe and life-threatening allergic reaction that can be fatal. Severe symptoms such as a swollen tongue, difficulty breathing or becoming unconscious usually develop suddenly, often within minutes after being exposed to an allergy trigger such as a particular food, latex, insect stings or certain drugs.