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An estimated 20% of people in the U.S. have hives at least once during their lifetime. The sudden appearance of these extremely itchy, red or skin-colored bumps and welts, with or without swelling known as angioedema, can be triggered by reactions to certain food, pet dander, medications, viral or bacterial infections, or vaccines, for example. The good news, though, is that most episodes of hives or "acute urticaria" disappear within a day without treatment.

Hives that come and go for longer than 6 weeks are known as "chronic urticaria." Symptoms can recur for years, with severe itching, making it difficult to sleep, which can lead to poor performance at work or at school, and increased risk of anxiety and depression.

It's easy for acute urticaria to become chronic, said Alison Ehrlich, MD, of Foxhall Dermatology and Research Center in Washington, D.C. "You can kind of slide into chronic," she explained. "Let's say you have an allergy to shrimp but you don't know it and you like to eat shrimp once a month. You start having urticaria once a month, but it takes 6 months to figure out you're allergic to shrimp. So now your acute urticaria has become chronic."

The diagnosis of urticaria by a physician is an essential part of effective management. Diagnosis is also important for other reasons: to rule out conditions that mimic chronic urticaria, such as rosacea and eczema; and to identify conditions that can accompany chronic urticaria, such as thyroid disease.

In many cases, a thorough medical history along with physical examination of the affected areas is all that's required to diagnose the condition. Here's a rundown of the information to share with your physician at the first appointment.

Know Your History

Your doctor will ask about your personal and family history of medical conditions and diseases, including not just hives but also other allergic disorders. The doctor will also want to know if you've had a recent upper respiratory infection such as a cold or the flu, or if you have a history of chronic infection -- of the gallbladder, for instance, or the prostate in men -- since infection increases the risk of hives.

"If I have a patient with chronic urticaria, asking about a recent infection or symptoms of infection is important," said Jenny Murase, MD, of the University of California, San Francisco. "I ask my patients whether they have tooth pain [oral infection], pain on urination [urinary tract infection], a cheesy vaginal discharge [yeast infection], or symptoms of gastroesophageal reflux disease or GERD, such as burping and a burning sensation in the chest after eating."

Your doctor will also likely ask you about recent travel, including camping; whether you have had any insect bites, including ticks; and symptoms that may indicate the presence of underlying disease, such as fever, weight loss, joint stiffness, arthritis, abdominal pain, bone pain, and heat or cold sensitivity.

Bring Photos

Your physician will want to know when the hives started and where, what they looked like, whether they occurred daily or less often, and for how long. Since you may not be experiencing a flareup of hives at the time of your appointment, take photos beforehand.

Recognize Angioedema

In about 40-50% of cases, hives are accompanied by angioedema in the deeper layers of the skin. This can cause swelling of the fingers, hands, lips, tongue, throat, and/or genitals. Your doctor will want to know if you've had angioedema, and whether it was accompanied by other symptoms.

"I ask my patient if they are experiencing headache, swelling, fatigue, flushing, wheezing, breathlessness, gastrointestinal symptoms, or heart palpitations because they indicate an increased risk of anaphylaxis," said Ehrlich.

Keep a Food Diary

If you get hives every time you eat peanuts, there may be a link. Sharing a food diary with your physician will help identify allergens to avoid. If a specific food appears to be the culprit, your physician may do a skin-prick test or a blood test to confirm the diagnosis. Your doctor will also want to know about other potential allergens you've been exposed to, such as pet dander.

Provide a Drug Inventory

Bring a list of the medications you take on a regular basis, including aspirin, ibuprofen, or naproxen, as well as any hormone therapies such as birth control pills. If you are taking medication for blood pressure or diabetes, include the doses prescribed, and remember to document any new medication, especially antibiotics. Even with all this information, however, it may not be possible to identify the specific trigger.

Physical Causes

Some 20% of chronic urticaria is associated with physical and environmental triggers such as heat, cold, vibration, sunlight, pressure from tight clothing, and even scratching. This is known as "chronic inducible urticaria" (CIndU).

Conclusion

In 80% of all chronic urticaria cases, however, no allergen or trigger can be identified. This is known as "chronic spontaneous urticaria" (CSU). Most cases of CSU can be controlled with a layered drug regimen, starting with a long-acting, non-sedating antihistamine.

Additional Resources

Read previous installments in this series:

For Your Patients: All About Hives

For Your Patients: Understanding the Many Different Types of 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.