by Jennifer Hellwig, MS, RD
En Espaol (Spanish Version) Hives are small, red swellings on the skin, occurring singularly or in clusters. They tend to fade away after a few hours, but new ones can appear. Most cases of hives resolve within a few days, but some can take a few weeks or even longer.
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Hives are caused by a reaction in which certain cells of the body release a substance called histamine, a substance released by many cells during an allergic reaction. Many people, however, develop hives without any possible exposure to allergy-producing substances. In fact, the cause of a hive reaction is often unknown, but it may include:
- Foods, most commonly:
- Eggs
- Shellfish
- Nuts
- Chocolate
- Fish
- Tomatoes
- Fresh berries
- Milk
- Medications
- Reaction to allergy shots (desensitization shots)
- Infections
- Insect bites or stings
- Latex
- Pressure
- Cold or heat
- Sunlight
- Thyroid disease
- Pollen
- Stress
- Vasculitis
A risk factor is something that increases your chance of getting a disease or condition.Exposure to anything that produces an allergic reaction (ie, an allergen ) can increase your risk of hives. Also, situations that have produced hives in the past often produce them again.
Symptoms Symptoms of hives can vary from mild to severe: ItchinessRednessSwellingExcessive swelling of the eyelids, lips, or genitalsBurningStingingDifficulty breathing or swallowing (Seek immediate medical care if you have these symptoms.) Diagnosis The doctor will ask about your symptoms and medical history, and perform a physical exam. You may be referred to a doctor who specializes in skin disorders (dermatologist) and/or allergies (allergist). To help determine if your hives are related to certain allergies, a skin prick test may be done. To perform this test, your doctor places a tiny bit of an allergen in your skin with a needle and watches to see if the skin in that area becomes raised or irritated. The doctor may also perform a skin biopsy and order blood tests or x-rays to look for possible causes. TreatmentThe best way to treat hives is to identify and avoid the cause. Since this is often not possible, there are a number of medications for treating hives: Over-the-counter antihistamines such as: DiphenhydramineHydroxyzineCyproheptadine Prescription antihistamines such as: Fexofenadine (Allegra)Loratadine (Claritin)Acrivastine (Semprex)Cetirizine (Zyrtec)DoxepinHydroxyzine (Atarax)Levocetirizine (Xyzal) H2 blocking medications such as: CimetidineRanitidineFamotidineAnti-inflammatory medicationsSteroid skin creamsOral steroid medications (prednisone) for hives resistant to other treatmentsUltraviolet light therapyPrescription epinephrine (adrenalin) injections for cases when swelling affects the airways PreventionThe best way to prevent hives is to avoid substances or situations that have caused you to get hives in the past.
Resources: American Academy of Allergy, Asthma, and Immunologyhttp://www.aaaai.org American Academy of Dermatologyhttp://www.aad.org CANADIAN RESOURCES: Canadian Dermatology Associationhttp://www.dermatology.ca/english/ Dermatologists.cahttp://www.dermatologists.ca/index.html References: American Academy of Allergy, Asthma, and Immunology website. Available at: http://www.aaaai.org . American Academy of Dermatology website. Available at: http://www.aad.org . Dibbern DA Jr. Urticaria: selected highlights and recent advances. Med Clin North Am. 2006;90:187-209. Review. Gambichler T, Breuckmann F, Boms S, Altmeyer P, Kreuter A. Narrowband UVB phototherapy in skin conditions beyond psoriasis. J Am Acad Dermatol. 2005;52:660-670. Review. Guldbakke KK, Khachemoune A. Etiology, classification, and treatment of urticaria. Cutis. 2007;79:41-49. Review. National Institute of Arthritis and Musculoskeletal and Skin Diseases website. Available at: http://www.niams.nih.gov/ . Last reviewed December 2007 by Ross Zeltser, MDPlease be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
