ANAPHYLAXIS - SYMPTOMS 

Symptoms  of anaphylaxis generally begin within minutes to an hour of exposure to  a trigger. Less commonly, symptoms do not develop for several hours. 

The most common symptoms of anaphylaxis are hives (urticaria) and swelling of the skin (angioedema), which occur in 80  to 90 percent of reactions. Respiratory symptoms occur in about 50 percent of reactions,  and are especially common in people who also have asthma or another chronic respiratory disease. Extremely low blood pressure, causing lightheadedness, dizziness, blurred vision, or loss  of consciousness (passing out) occurs in about 30 percent  of reactions.

Anaphylaxis  can cause symptoms throughout the body: 

• Skin: Itching, flushing, hives (urticaria), or  swelling (angioedema) 
• Eyes: Itching, tearing, redness, or swelling  of the skin around the eyes 
• Nose and mouth: Sneezing, runny nose, nasal congestion,  swelling of the tongue, or a metallic taste 
• Lungs and throat: Difficulty getting air  in or out, repeated coughing, chest tightness, wheezing or other sounds of labored breathing, increased mucus production, throat swelling or itching, hoarseness, change in voice, or a sensation of choking 
• Heart and circulation: Dizziness, weakness, fainting, rapid, slow, or irregular heart rate, or low blood pressure 
• Digestive system: Nausea, vomiting, abdominal cramps,  or diarrhea 
• Nervous system: Anxiety, confusion, or a sense of impending doom 

A severe form of anaphylaxis causes sudden collapse without other obvious symptoms, such as hives or flushing. This form of anaphylaxis occurs most commonly after a person is given a medication into a vein or is stung by an insect. 

Up to 20 percent of people with anaphylaxis have biphasic (two-phase) or protracted (prolonged) anaphylaxis. A person with biphasic anaphylaxis has a reaction that resolves and then recurs hours later without further exposure to the trigger. The late phase reaction usually occurs within eight hours, but may occur up to 72 hours after the initial symptoms. A person with protracted anaphylaxis has signs and symptoms that persist for hours or even days despite treatment, although this is rare.