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Hives

These are raised, itchy, red bumps on your skin. They can be called “welts.” They can be an allergic reaction to an allergen. They can also show up without a cause and maybe autoimmune-like.

Sep 14, 2020

Causes

Your body releases histamine and other chemicals into the blood when you have an allergic reaction. These chemicals can cause symptoms such as itching, swelling, and other symptoms, like hives.

Angioedema is swelling of the deeper tissue that sometimes happens with hives. This type of swelling can be life threatening if it involves your mouth or throat.

Substances that can act as allergens and can trigger hives are:

  • Animal dander, pollen, mold, dust mite
  • Insect bites or stings
  • Medicines
  • Foods, such as milk, wheat, eggs, nuts, soy, seafood.

You can get them from:

  • Stress
  • Extremes of temperature
  • Pressure
  • Sweating or exercise
  • Illness, such as lupus, other autoimmune diseases, and leukemia
  • Infections, like viruses
  • Exposure to water, sun, vibration

The cause of hives in often not known. This may mean the cause could be autoimmune.

Symptoms can be:

  • Itching
  • Swelling of the top layer of the skin into red- and/or white-colored welts with clearly defined edges.
    • These are called wheals.
  • Hives may get bigger, spread, and join together to form larger areas.
    • Wheals can change shape, disappear, and reappear within minutes or hours. It is not normal for a wheal to last more than 24 hours.
  • Dermatographism is a type of hives. This is also known as skin writing.
    • It is caused by pressure on the skin. Hives then appear on the parts of your body that were stroked.

Exams and tests

  • A skin exam can diagnose hives.
  • A skin biopsy might be done if it could be something other than hives.
  • Skin test or blood tests might be done to test for an allergy.
    • Specific allergy testing is not useful in most cases of chronic hives.

Treatment

  • Do not take hot baths or showers.
  • Do not wear tight-fitting clothing. This can irritate your skin.
  • Antihistamine such as diphenhydramine (Benadryl) or cetirizine (Zyrtec).
  • Other oral prescription medicines, like steroids, immunosuppressants or immunomodulators. You may need these if the hives are chronic (long-lasting).
  • Anti-IgE therapy, such as omalizumab, is a medicine to target a specific part of your allergy immune system.

To learn more

Last reviewed September 2020