Signs and symptoms of chronic hives include:

• Batches of red or skin-colored welts (wheals), which can appear anywhere on the body
• Welts that vary in size, change shape, and appear and fade repeatedly as the reaction runs its course
• Itching, which may be severe
• Painful swelling (angioedema) of the lips, eyelids and inside the throat
• A tendency for signs and symptoms to flare with triggers such as heat, exercise and stress
• A tendency for signs and symptoms to persist for more than six weeks and to recur frequently and unpredictably, sometimes for months or years

Short-term (acute) hives appear suddenly and clear up within a few weeks.

The welts that come with hives arise when certain cells release histamine and other chemicals into your bloodstream.

Doctors often can't identify the reason for chronic hives or why acute hives sometimes turn into a long-term problem. The skin reaction may be triggered by:

• Pain medications
• Insects or parasites
• Infection
• Scratching
• Heat or cold
• Stress
• Sunlight
• Exercise
• Alcohol or food
• Pressure on the skin, as from a tight waistband

In some cases, chronic hives may be related to an underlying illness, such as a thyroid disease or, rarely, cancer.

Chronic hives don't put you at any sudden risk of a serious allergic reaction (anaphylaxis). But if you do experience hives as part of a serious allergic reaction, seek emergency care. Signs and symptoms of anaphylaxis include dizziness, trouble breathing, and swelling of your lips, eyelids and tongue.