麻豆果冻传媒影音

There are many different types of hives -- urticaria -- with many different causes. In most cases, these puffy, red, or skin-colored bumps and wheals appear suddenly due to an allergic reaction to foods such as shellfish, nuts, or eggs; drugs such as antibiotics; allergens such as pollen or animal dander; or following a viral infection such as a cold or the flu.

Extreme cold, excessive perspiration, and other physical factors can also cause hives, and underlying conditions such as thyroid disease, chronic infection, and even stress, can play a role.

Getting to the bottom of what's causing your hives can be a challenge. Fortunately, when they appear soon after an insect bite, eating shrimp, or wearing a tight waistband, the odds are that you and your doctor will be able to identify the cause. And importantly, this will make it possible for you to avoid or eliminate this "trigger" in the future.

Most hives disappear within a day or so, often without treatment, or they may come and go for up to 6 weeks. Doctors refer to these hives as "acute urticaria." Hives that recur several times a week for longer than 6 weeks are called "chronic urticaria." In about half of patients with "chronic spontaneous urticaria" (CSU), a type of chronic urticaria that accounts for 80% of cases, the cause is never identified.

The good news? There are safe, highly effective treatments that can relieve symptoms, even when the cause remains a mystery. "For the vast majority of patients with acute urticaria and also a good chunk of patients with chronic urticaria, the symptoms can be controlled with antihistamines," said Jenny Murase, MD, of the University of California, San Francisco and director of Medical Dermatology Consultative Services and Patch Testing for the Palo Alto Foundation Medical Group.

Experts caution that the importance of treating hives should not be underestimated. Persistent itch, one of the most troubling symptoms, can rob you of sleep, set you up for poor performance at work or school, and increase the risk of anxiety and depression.

For mild hives, your doctor may recommend an over-the-counter, second-generation H1 antihistamine such as fexofenadine (Allegra), loratadine (Claritin), cetirizine (Zyrtec), or desloratadine (Clarinex). These medications do not cause drowsiness and are considered safer than the older, first-generation H1 antihistamines such as diphenhydramine (Benadryl). Importantly, the dose can be increased when itch and other allergic symptoms are more severe.

Your doctor may also decide to add an H2 antihistamine such as famotidine (Pepcid) or cimetidine (Tagamet) to your treatment regimen. This approach, known as "antihistamine layering," increases the effectiveness of a second-generation H1 antihistamine to control symptoms.

Should symptoms persist, treatment with omalizumab (Xolair) is recommended. This biologic agent, which is administered by monthly injection, is the only treatment currently approved by the FDA for urticaria that doesn't respond to a second-generation H1 antihistamine.

Omalizumab is highly effective and safe for the treatment for CSU as well as for "chronic inducible urticaria," which is seen in the remaining 20% of patients with chronic urticaria. Omalizumab also helps prevent swelling in the deeper tissues of the skin. Known as "angioedema," this can be part of a life-threatening whole-body allergic reaction called anaphylaxis.

Omalizumab has been a game-changer for patients who don't get enough symptom relief with antihistamines, Murase said, noting that not only does it do a great job of controlling symptoms, but it doesn't require patients to undergo the extensive bloodwork needed when an immunosuppressive agent is prescribed. At present, conventional immunosuppressants such as cyclosporine are recommended only when urticaria does not respond to any dose of antihistamine or to omalizumab.

"Omalizumab is a good therapy, but some patients may not be comfortable with giving themselves a monthly injection," said Jonathan I. Silverberg, MD, PhD, MPH, director of Clinical Research and Contact Dermatitis at George Washington University School of Medicine and Health Sciences in Washington, D.C. "This could make it more cumbersome and complicated for patients who have to go to an office or institutional setting. We can certainly use more oral options that are safe and effective."

The use of topical corticosteroids such as hydrocortisone cream is not useful for the treatment of hives, according to international clinical guidelines. Similarly, the use of systemic corticosteroids like prednisone outside of specialty care is not recommended due to the risk of long-term side effects.

Additional Resources:

Read previous installments in this series:

For Your Patients: All About Hives

For Your Patients: Understanding the Many Different Types of Hives

For Your Patients: How Will My Doctor Diagnose Hives?

"Medical Journeys" is a set of clinical resources reviewed by physicians, meant for the medical team as well as the patients they serve. Each episode of this journey through a disease state contains both a physician guide and a downloadable/printable patient resource. "Medical Journeys" chart a path each step of the way for physicians and patients and provide continual resources and support, as the caregiver team navigates the course of a disease.