Hives are welts on the skin that are very itchy. These welts can appear on any part of the skin. Hives vary in size from as small as a pen tip to as large as a dinner plate. They may connect to form even larger welts.
Individual hives go away in 24 hours, often in only a few hours. However, new hives may appear as old ones fade, so hives may last for a few days or longer. A stint of hives usually lasts less than six weeks. These hives are called acute hives. If hives last more than six weeks, they are called chronic hives.
The medical term for hives is urticaria. Urticaria in some individuals is also associated with swelling. When large welts occur deeper under the skin, the medical term is angioedema. This can occur with hives, and often causes the eyelids and lips to swell. If this occurs, you need emergency care right away.
What causes acute hives?
An allergic reaction to many different things can trigger hives. In general, hives related to an allergic trigger go away quickly once the trigger is removed. The most common allergen triggers for acute hives include:
- Foods: Milk, eggs, peanuts, tree nuts, and shellfish
- Insect bites and stings
- Animal dander
- Touching something to which you are allergic, such as latex
- Allergy shots
Other causes of hives are:
Infections, including colds and infections caused by some bacteria or fungi
- Exposure to sun (solar urticaria), heat, cold, or water
- Pressure on the skin, such as from sitting too long
- Contact with chemicals
- Scratching the skin, also called dermatographism
How is Chronic Urticaria Treated and Managed?
The best treatment for urticaria is to identify and avoid the trigger. However, in chronic urticaria, there is rarely an identified cause for the hives. In the majority of cases, allergy is not playing a role. When the cause is unknown, medications can be used to control symptoms and prevent breakouts.
- Antihistamines. The first-line treatment recommended for urticaria is non-sedating H1 antihistamines, such as: loratadine (Claritin), fexofenadine (Allegra), and cetirizine (Zyrtec). These medications block H1 receptors, and are effective in reducing symptoms of hives with very few adverse effects reported. If these medications don’t help, H2 antihistamines such as cimetidine or ranitidine (which block H2 receptors) may be added. Although H2 antihistamines are not effective for urticaria when used along, the combination of these two types of blockers sometimes provides more effective relief. For more severe urticaria, the more potent antihistamines, such as diphenhydramine (Benadryl) and doxepin, may be used; however, these drugs tend to cause drowsiness and other side effects.
- Corticosteroids. For some people with chronic urticaria, antihistamines do not provide relief; in these cases, other forms of treatments, such as corticosteroids, may be prescribed. A short course of an oral corticosteroid or a single dose of an injectable steroid can be prescribed for an acute episode of urticaria that is nonresponsive to antihistamines. Because of serious side effects with prolonged use, long-term use of these medicates is avoided when possible. Doctors prescribe the lowest possible effective dose for the shortest period of time.
- Other therapies. There are multiple other steroid-sparing medications available that have shown to be effective in the treatment of chronic hives. For some people with chronic idiopathic urticaria, omalizumab (Xolair) may be prescribed. This treatment is the first biologic medicine approved for CIU, and can be effective for certain people with CIU who remain symptomatic despite treatment with H1 antihistamine therapy.
Treatment for chronic urticaria must be individualized and monitored under close medical supervision. There are ongoing research studies for hives. To see if you qualify, find out more here.