Anaphylaxis is a life-threatening type of allergic reaction.
Symptoms
Symptoms develop rapidly, often within seconds or minutes. They may include the following:
Abdominal pain or cramping
Abnormal (high-pitched) breathing sounds
Anxiety
Confusion
Cough
Diarrhea
Difficulty breathing
Fainting, light-headedness, dizziness
Hives, itchiness
Nasal congestion
Nausea, vomiting
Sensation of feeling the heart beat (palpitations)
Skin redness
Slurred speech
Wheezing
Treatment
Anaphylaxis is an emergency condition requiring immediate professional medical attention. Call 911 immediately.
Check the ABCs (airway, breathing, and circulation from Basic Life Support) in all suspected anaphylactic reactions.
CPR should be started, if needed. People with known severe allergic reactions may carry an Epi-Pen or other allergy kit, and should be helped if necessary.
Paramedics or physicians may place a tube through the nose or mouth into the airways (endotracheal intubation) or perform emergency surgery to place a tube directly into the trachea (tracheostomy or cricothyrotomy).
Epinephrine should be given by injection in the thigh muscle right away. This opens the airways and raises the blood pressure by tightening blood vessels.
Treatment for shock includes fluids through a vein (intravenous) and medications that support the actions of the heart and circulatory system.
The person may receive antihistamines, such as diphenhydramine, and corticosteroids, such as prednisone, to further reduce symptoms (after lifesaving measures and epinephrine are administered).
Causes
Anaphylaxis is an severe, whole-body allergic reaction. After being exposed to a substance like bee sting venom, the person's immune system becomes sensitized to that allergen. On a later exposure, an allergic reaction may occur.
This reaction is sudden, severe, and involves the whole body.
Tissues in different parts of the body release histamine and other substances. This causes the airways to tighten and leads to other symptoms
https://health.google.com/health/ref/Anaphylaxis