Hives are red, itchy welts on the skin that come and go over the course of minutes or hours. All types of hives can cause itching. They usually form on the skin but sometimes also in the soft tissues of the mouth, eyes and throat.
In an allergic reaction, a person's immune system has been "primed", or "sensitized" to any one of a number of foods, medications, or other substances from the environment. In response to the substance, the immune cells release a chemical known as histamine. Histamine, in turn, acts on the capillaries in the skin, causing them to dilate and leak fluids. These fluids collect under the skin in welts which we recognize as hives.
Hives are characterized by itchy red welts and swelling of facial features. On occasion, hives can cause a life-threatening reaction that involves the whole body rather than just the skin. This is called anaphylaxis.
There are several known factors that cause histamines to be released, and hives to form. These include: allergy to medications or substances in the environmentacute or chronic infectionsfoodsunderlying systemic disease such as asthma, a condition that causes inflammation and obstruction of the airways in the lungsblood products given intravenously, or into the veinscratchingheat or coldexposure to sunlight
Anaphylaxis is a medical emergency that can cause difficulty breathing and lead to death. It is important to call for emergency medical assistance immediately if anaphylaxis is suspected.
Antihistamine medications, such as diphenhydramine (i.e., Benadryl), cetirizine (i.e., Zyrtec) or loratadine (i.e., Alavert, Claritin), can be used to prevent hives. An individual should also avoid the substance that provoked the reaction if it is known. Epinephrine is used to treat severe reactions such as anaphylaxis.
A healthcare professional can diagnose hives after examining the affected person and listening to an account of the event.
Hives cause: discomfortskin irritation and breakdownskin infection
Hives are not contagious.
Hives can be treated in the following ways: identifying and removing the substance that provoked the outbreakusing oral antihistamines such as diphenhydramine, cetirizine or loratadineusing oral corticosteroids such as prednisonegiving epinephrine for anaphylaxis
Both oral antihistamines and oral corticosteroids can have side effects, such as drowsiness, dry mouth, constipation and the inability to urinate. Antihistamines, especially the older ones such as diphenhydramine, can cause more severe reactions in the elderly.
Hives generally clear up without any long term problems. However, it is important to identify the cause and treat any underlying conditions.
If hives occur frequently, a healthcare professional should be consulted.