Soon after attending an outdoor crab feast, a few raised, itchy welts appear on your neck. Were you bitten by a mosquito or did the shellfish cause you to break out in hives?
Distinguishing symptoms of hives, or urticaria, from a regular bug bite can be tricky, but it helps to keep a few things in mind:
- Hives symptoms can appear on any area of the body and often change shape, move around, disappear, and reappear over short periods of time
- The bumps—red or skin-colored “wheels” with clear edges—tend to come on suddenly and go away just as fast
- When pressing the center of a red hive, it turns white, in a process called “blanching”
There are two types of hives—short-lived (acute) hives and long-term (chronic) hives—but neither is typically life threatening. Hives are often caused by allergens such as pet dander, insect bites, medication, pollen, and latex and foods such as crab and other shellfish, nuts, eggs, and milk. They can also be triggered by emotional stress, extreme cold or sun exposure, excessive sweat, or infections.
When acute hives do appear, they can last just one day or as long as six weeks. Chronic hive sufferers experience longer lasting symptoms—sometimes for more than six weeks—that are more painful than itchy. The sore hives may last for as long as 24 hours and, when they go away, leave the skin bruised. In such cases, the cause may be inflammation of the blood vessels, or vasculitis.
An allergist can help diagnose and treat hives. An allergist may take the patient’s history to determine what allergen is causing the outbreak or administer a skin test to help avoid further attacks. The allergist may then recommend therapies ranging from cool compresses to relieve itching and pain to prescription antihistamines or other medications, such as an epinephrine injector or steroids. Seek immediate emergency care when swelling in the throat restricts breathing.
If your hives last over a month or are chronic, see an allergist for an evaluation.
Is it hives or angioedema?
Angioedema symptoms, which also may stem from allergic reactions, are similar to hives except the swelling is below the surface of the skin (sometimes in addition to above-the-surface welts). The following symptoms may indicate angioedema:
- Swollen eyes and mouth
- Swelling on the hands, feet and throat
- Swelling that forms a line or is spread out
- Difficulty breathing, stomach cramping, or chemosis (the swelling of the lining of the eyes)
Both hives and angioedema may occur after infections or with other illnesses. An allergist can help diagnose and treat angioedema as well.