Symptoms and causes

Symptoms

Hives

The welts associated with hives can be:

 
  • Red or flesh-colored
  • Intensely itchy
  • Roughly oval or shaped like a worm
  • Less than one inch to several inches across

Most hives go away within 24 hours. Chronic hives can last for months or years.

Angioedema

Angioedema is a reaction similar to hives that affects deeper layers of your skin. It most commonly appears around your eyes, cheeks or lips. Angioedema and hives can occur separately or at the same time.

Signs and symptoms of angioedema include

  • Large, thick, firm welts
  • Swelling and redness
  • Pain or warmth in the affected areas

When to see a doctor

You can usually treat mild cases of hives or angioedema at home. See your doctor if your symptoms continue for more than a few days. Seek emergency care if you feel your throat is swelling or if you're having trouble breathing.

Causes

Hives and angioedema can be caused by:

  • Foods. Many foods can trigger reactions in people with sensitivities. Shellfish, fish, peanuts, tree nuts, eggs and milk are frequent offenders.
  • Medications. Almost any medication may cause hives or angioedema. Common culprits include penicillin, aspirin, ibuprofen (Advil, Motrin IB, others), naproxen (Aleve) and blood pressure medications.
  • Common allergens. Other substances that can cause hives and angioedema include pollen, animal dander, latex and insect stings.
  • Environmental factors. Examples include heat, cold, sunlight, water, pressure on the skin, emotional stress and exercise.
  • Underlying medical conditions. Hives and angioedema also occasionally occur in response to blood transfusions, immune system disorders such as lupus, some types of cancer such as lymphoma, certain thyroid conditions, and infections with bacteria or viruses such as hepatitis, HIV, cytomegalovirus, and Epstein-Barr virus.
  • Genetics. Hereditary angioedema is a rare inherited (genetic) form of the condition. It's related to low levels or abnormal functioning of certain blood proteins that play a role in regulating how your immune system functions.

Risk factors

Hives and angioedema are common. You may be at increased risk of hives and angioedema if you:

  • Have had hives or angioedema before
  • Have had other allergic reactions
  • Have a disorder associated with hives and angioedema, such as lupus, lymphoma or thyroid disease
  • Have a family history of hives, angioedema or hereditary angioedema

Complications

Severe angioedema can be life-threatening if swelling causes your throat or tongue to block your airway.