Are hives (urticaria) contagious?
Hives are a particular rash that's characterized by itchy, raised, whitish or pinkish welts on the skin. They may occur on one area of the body, such as the stomach or arms, or occur all over the body. Hives rash is triggered by the release of histamine in the skin and is caused by an allergic response. A wide variety of foods, medicines, conditions, and chemicals can cause hives, including foods (such as strawberries and seafood), drugs (such as penicillin and sulfa), and infections (viral, bacterial, and parasites). Frequently, the agent that triggers a hives rash is not detected. Hives are also known as urticaria.
Hives themselves are not contagious unless they contain agents such as viruses that can be transmitted from an infected individual to another. The vast majority of hives are not contagious. Hives occur more frequently in children and in females. In general, hives decrease and disappear within about 24-48 hours if the affected individual is no longer exposed to the allergic agent. If hives last longer than days or weeks, they may be termed chronic urticaria.
How long will it be before someone knows if he or she is going to get hives?
Because hives are response to a large number of different triggering agents, most people don't know if they're going to get hives until they encounter the agent. Sometimes hives occur rapidly within a few minutes to hours after contacting the triggering agent. Other times hives may take longer to develop. About 70% of patients who develop hives initially do not know when they encountered the triggering agent. Often the triggering agent is not identified. Some patients know immediately if they're going to get hives if they inadvertently contact the triggering agent that has caused them to develop hives in the past. Pregnant women are at increased risk of developing hives.
The goal of treating most cases of ordinary urticaria is to relieve symptoms while the condition goes away by itself. The most commonly used oral treatments are antihistamines, which help oppose the effects of the histamine leaked by mast cells. The main side effect of antihistamines is drowsiness.
When will someone no longer get hives?
Hives are not contagious but result from an agent that is not normally in the body that triggers an allergic response. Individuals who become desensitized to substances that used to trigger hives will no longer get them. This may occur as the patient gets older or by desensitization procedures by a specialty physician (immunologist or dermatologist). Alternatively, individuals who know their triggers will no longer get hives if they avoid them (for example, avoiding foods or medicines that are known to cause hives in a particular individual).
How do hives spread?
Hives are not contagious and are not spread from person to person. For an individual affected by hives, the rash can occur in localized areas or over many areas such as the chest, back, and extremities. For some individuals, the stronger the allergic response, the more quickly and widespread over the body hives may be. Antihistamines such as diphenhydramine (Benadryl) or hydroxyzine (Atarax) may prevent or reduce spread of hives an individual. Epinephrine may be used in treating severe hives.
What specialists treat hives?
Most patients who develop hives will need no medical treatment. Although pediatricians and primary care physicians can treat hives, sometimes some specialists are needed. Specialists who often treat hives are emergency-medicine specialists, dermatologists, and allergy and immunology specialists.
Are there home remedies for hives?
If your hives are mild and you need no emergency care, there are things that can help reduce symptoms of hives. To possibly prevent or at least reduce the symptoms associated with hives, you can do the following:
- Cool the area that has hives with a cool shower, wet towels, or a fan.
- Wear loose, light clothing to decrease any irritation of the skin.
- Do not scratch or irritate the area.
- Avoid any known triggers of hives.
- For some patients, topical lotions may soothe the skin.
When should someone seek medical care for hives?
If hives become widespread and the person develops any wheezing, throat tightening, difficulty swallowing, and/or shortness of breath, the individual or the individual's parents should immediately seek emergency care. Such individuals may require injected epinephrine (EpiPen) to prevent airway compromise. Patients who have chronic urticaria should contact their doctors for an evaluation.
Medically Reviewed on 7/18/2018
Wong, Henry K. "Urticaria." Medscape.com. June 13, 2018. <http://emedicine.medscape.com/article/762917-overview>.