Symptoms

Anaphylaxis symptoms usually occur within minutes of exposure to an allergen. Sometimes, however, anaphylaxis can occur a half-hour or longer after exposure. In rare cases, anaphylaxis may be delayed for hours. Signs and symptoms include:

• Skin reactions, including hives and itching and flushed or pale skin
• Low blood pressure (hypotension)
• Constriction of the airways and a swollen tongue or throat, which can cause wheezing and trouble breathing
• A weak and rapid pulse
• Nausea, vomiting or diarrhea
• Dizziness or fainting

When to see a doctor

Seek emergency medical help if you, your child or someone else you're with has a severe allergic reaction. Don't wait to see if the symptoms go away.

If you have an attack and you carry an epinephrine autoinjector, administer it right away. Even if symptoms improve after the injection, you still need to go to an emergency room to make sure symptoms don't recur, even without more exposure to the allergen. This second reaction is called biphasic anaphylaxis.

Make an appointment to see your provider if you or your child has had a severe allergy attack or signs and symptoms of anaphylaxis in the past.

The diagnosis and long-term management of anaphylaxis are complicated, so you'll probably need to see a doctor who specializes in allergies and immunology.