Anaphylaxis symptoms can come on quickly, developing within minutes after exposure to an allergic trigger, but they can also ease and then return hours later or develop up to two hours after exposure. The sooner you seek help for the condition, the less severe the symptoms are likely to become.

The most dangerous symptoms of anaphylaxis affect the respiratory system (breathing) and/or cardiovascular system (heart and blood pressure). Symptoms can include some or all of the following:

• Hives, itchiness and redness on the skin, lips, eyelids or other areas of the body

• Wheezing and/or difficulty breathing

• Swelling of the tongue, throat and nose

• Nausea, stomach cramping and vomiting or diarrhea

• Dizziness and fainting or loss of consciousness, which can lead to shock and heart failure