Updated November 11, 2014.
Written or reviewed by a board-certified physician. See About.com's Medical Review Board.
What Are Hives?
Hives, also known as urticaria, is a common skin rash that can affect 1 in 5 people. Hives are typically raised, red and itchy, and can be of various shapes and sizes. The rash will tend to come and go within a few hours, moving from one place on the body to another. Hives don’t normally leave any bruising, scars or skin dryness or peeling. The itching is usually mild, although can be severe, but people with hives don’t normally scratch the skin to the point of bleeding.
Any of these characteristics may mean that the rash doesn’t represent hives.
What Are the Causes of Hives?
Hives are caused by the release of histamine into the skin by mast cells present in the skin and mucous membranes. This may occur through an allergic process or one in which mast cells release chemicals without IgE being involved. The most common cause of hives, particularly in children, is a viral infection. Hives can also be caused by other infections, such as strep throat, athlete’s foot and even urinary tract infections. Chronic infections, such as viral hepatitis, sinus infections and urinary tract infections, can cause chronic hives. Some studies have shown that infection with Helicobacter pylori, bacteria commonly connected with stomach ulcers, is also associated with chronic hives.
Allergic reactions, such as to foods and medicines, can also cause hives. Hives that occur as a result of a food allergy almost always appear within a few minutes to a few hours after eating the food.
Reactions to medicines may occur after the first dose, or sometimes not until the medication has been taken for a week or two, such as the case with antibiotics. The use of certain medications, particularly non-steroidal anti-inflammatory drugs (NSAIDs), can also be associated with hives.
When other allergies (other than foods or medicines), cause hives, pet allergy is usually to blame. Pollen, mold or dust mite allergies only rarely cause hives.
Stress is another common cause of hives. A person may not feel particularly stressed, but the body can be stressed, especially the person has a hectic lifestyle. Even if the stress is “good”, such as with going on vacation, the body might respond as having hives as a result.
Metabolic diseases, such as low or high thyroid function, liver disease and kidney disease, may also be at the root of chronic hives. In addition, it appears that a large percentage of people without an obvious trigger for their chronic hives actually have an autoimmune disease -- a condition in which the immune system attacks healthy tissue, including skin.
What is the Best Way to Treat Hives?
The best treatment for hives is with an antihistamine. Antihistamines are usually given in pill or liquid form, and may need to be given in large or frequent doses to control the symptoms. Short courses of corticosteroids may be needed, and rarely, if the symptoms are severe, epinephrine shots can be used for immediate, but temporary, relief.
Older antihistamines, such as Benadryl (diphenhydramine) or ChlorTrimeton (chlorpheniramine), are considered to be too sedating for the routine treatment of urticaria. In addition, older antihistamines need to be taken multiple times a day, as their antihistamine effects are very short acting. Newer antihistamines, such as Claritin (loratadine), Allegra (fexofenadine) and Zyrtec (cetirizine), are better choices for the treatment of hives since these antihistamines are less sedating and generally work for 24 hours. Most newer antihistamines, with the exception of Clarinex (desloratadine) and Xyzal (levocetirizine), are available over-the-counter without a prescription.
If the cause of the urticaria is known or suspected, such as a food or medicine, avoidance of the trigger may resolve the symptoms. In most cases, the symptoms of hives only last a few days, and often the cause is never known. If the symptoms of hives last for many weeks or a couple of months, then an allergist should be consulted for an appropriate testing and treatment.
Source:
Practice Parameters for Disease Management: Acute and Chronic Urticaria and Angioedema. Ann Allergy. 2000; 85: S525-44.
DISCLAIMER: The information contained in this site is for educational purposes only, and should not be used as a substitute for personal care by a licensed physician. Please see your physician for diagnosis and treatment of any concerning symptoms or medical condition.