Hives or welts, also called urticaria, are red, very itchy, swollen areas of the skin. Hives arise suddenly and they often appear in clusters, with new clusters appearing as other areas clear. Clusters may leave as quickly as one or two hours or can last as long as 24 hours. Almost one-quarter of the population will have an eruption of hives at some point in their lives.
Hives develop for a variety of reasons. Once hives start, one or more factors (such as stress) can keep them active. They generally worsen at night and develop at sites of pressure (waistband, feet, buttock, etc). Initially, a number of medicines may need to be prescribed to help control symptoms. Once the hives begin to resolve, medications may be decreased.
What causes hives?
Hives lasting less than six weeks are called “acute” and can be a side effect of eating certain foods or medications. Foods likely to cause hives in adults include nuts and seafood. Medications often responsible for producing hives include antibiotics, opioids, and NSAIDs such as aspirin. Viral infections are another common trigger of acute hives.
Sometimes hives will occur recurrently for longer than six weeks without an obvious cause. This is called chronic urticaria. While mainly nuisances and not associated with serious internal disease, the exact mechanism for this condition is not known and the hives usually disappear on their own. Some patients may have an autoimmune trigger to chronic hives.
What are some other causes of hives?
A common form of hives is dermatographism, which occurs in 5% of the population. The hives are caused by constant stroking or rubbing of the skin and often after scratching or when tight-fitting clothes rub the skin.
Cholinergic urticaria is the medical term for hives that develop after activities that increase the body’s temperature, including warm water, exercise, fever, or emotional stress. It is estimated that 5% to 7% of patients who have hives experience cholinergic urticaria.
Some individuals with exercise-triggered hives can also develop lung obstruction and/or lose consciousness. Such a severe reaction is called exercise-induced anaphylaxis.
Cold-induced hives occur after exposure to cold wind or water. Hives may appear on limbs and generally on any exposed area. Cold water or liquids can provoke symptoms on the lips or in the mouth.
What is angioedema?
While hives develop on the skin’s surface, angioedema is swelling in the deeper layers of skin, most often the hands, feet, and face. If the angioedema occurs in the throat, normal breathing or swallowing can be blocked and emergency measures must be taken. This is a rare occurrence, most angioedema causes swelling of the lips or eyes with no long-lasting effects. Hives and angioedema may appear together or separately. Angioedema usually lasts one to two days and may reoccur with or without hives over an indefinite period of time.
Hereditary angioedema is a rare inherited disease, which can be fatal and in this respect, differs from other types of chronic angioedema. Swelling can occur in the airways such as the larynx, tongue, and throat as well as on the face and extremities. Swelling in the stomach area can lead to severe pain and surgery for what is thought to be appendicitis. A blood protein deficiency is the cause of this inherited illness.
Is testing helpful for patients with hives?
When the hives completely resolve and antihistamines are discontinued, skin testing for acute cases can be performed if the medical history indicates. Some situations require blood tests to fully evaluate symptoms. Generally speaking, skin testing is not helpful for cases of chronic hives. Often hives resolve and no trigger is identified.
How can hives be treated?
Avoidance of the foods, drugs, or other provoking factors is recommended whenever possible. Antihistamines such as levocetirizine, cetirizine, fexofenadine, loratadine, and ranitidine are used to treat recurrent episodes. Use of these medications is recommended under the guidance of an allergist.
High-dose antihistamines can be especially effective for the treatment of chronic urticaria.
If hives do not respond to high dose antihistamine, allergists may utilize higher-level medications such as Xolair, which is an injection given every 2-4 weeks. Some patients will require short courses of steroids, but if possible, steroids should be avoided for chronic use.
In severe, acute cases where angioedema is involved, epinephrine injections may be necessary to alleviate the swelling. Hereditary angioedema can be very effectively treated with special medications.