Hives appear as bumps on the skin, the size of which can vary in size from pinhead sized to large areas several inches across. The individual lesions usually start as well demarcated, well circumscribed bumps but can grow and coalesce into larger areas involving most or all of an extremity or torso. The lesions usually have a reddish color, and blanch (become white) on direct pressure. Hives may last for a few minutes, up to hours, and occasionally up to 24 hours. The individual lesions usually come and go in less than 24 hours to be replaced by other newer lesions which in turn last less than 24 hours. Urticaria can occur for only a brief time of a few days, but they can also occur daily for many months or even years. Once the individual lesions disappear, there are no residual marks or scars.  If dark, discolored marks remain on skin after the hives have resolved this may suggest  another underlying medical illness.

Hives can be due to many things.   Unfortunately, many times, no cause is found.  Common causes include:

• An allergy to something, such as a food, spice or food addidive, medication (including over the counter medications), herbal or vitamin supplement, insect sting or even environmental allergens (ie pets, dust, pollen)
• Viral infections are common causes of hives.  Viral infections could just be from a cold, or something more serious such as hepatitis.
  
• Other types of infections, such as bacterial infections (a sinus infection, a tooth abscess, a ear infection) as well as a fungal or parasitic infection.
  
• Pregnancy (usually in first trimester)
• Diabetes
• Liver or kidney disease
• An Autoimmune disorder such as a thyroid disorders or lupus
  
• Stomach ulcers or gastritis associated with infection by H. Pylori (a common cause for stomach ulcers)
• Cancer (rarely)
• Contact sensitivty to soaps, detergents, cosmetics, creams, lotions, chemicals, or jewelry.
• Physical triggers such as physical exercise, heat, pressure, cold, water, sweating, vibration, sun light.
• Stress and anxiety are common causes of hives



Angioedema occurs when swelling develops in the deeper tissues of the skin or mucosal surfaces of the body.  This compares with hives (urticaria) where the swelling develops in the superficial areas of the skin.   Angioedema often involves the face, tongue, lips, throat, feet, the lining of the intestines, and genitalia.  The swelling may be painful or burning in character rather than itchy.  Occasionally the tongue or throat swelling may be so bad enough that it cause difficulties in talking or breathing – which can obviously be life threatening.    Most of the time, angioedema occurs at the same time as the hives develop.   The causes of angioedema are similar to the causes of hives.  Rarely angioedema can result from a hereditary disorder called hereditary angioedema.