In-depth

Symptoms

Headache

Most headaches aren't caused by a serious illness, but some could be a sign of a life-threatening condition.

Hives and angioedema

Hives and angioedema — Comprehensive overview covers symptoms, causes, treatment of these common allergic disorders.

Tachycardia

Tachycardia, a rapid heart rate, is caused by an abnormality in your heart's electrical impulses. Tachycardia can cause serious complications, including sudden cardiac arrest.

Tests and diagnosis

Allergy skin tests

Itching, sneezing and swelling: Find out what's causing your allergy symptoms.

Feb. 07, 2014

You Are ... The Campaign for Mayo Clinic

Mayo Clinic is a not-for-profit organization. Make a difference today.