“Chronic idiopathic hives are itchy red welts that persist for at least six weeks and have no known cause,” says Miriam Anand, MD, an allergist with Allergy Associates and Asthma in Tempe, Arizona. The condition is marked by periods of exacerbation and remission, and for many who have it, the hives may persist for more than five years. If you have chronic hives, it’s important to try to identify your triggers, if possible, and take steps to avoid them so you can lower the risk of an exacerbation. While you may already be aware of common triggers, such as allergies to pollen, pet dander, and shellfish, here are some lesser-known triggers of chronic hives: Here’s an additional reason to brush, floss, and see your dentist regularly: In a study published in April 2013 in the journal Advances in Dermatology and Allergology, researchers found that tooth decay and several other infections can play a significant role in the development of chronic hives. Bacterial infections (such as urinary tract infections and strep throat) and viral infections (such as hepatitis and norovirus, a common cause of stomach “flu”) were also found to be triggers of chronic hives. Also, if you have chronic hives, you may want to ask your doctor about getting tested for the antigen Heliobacter pylori, which is associated with chronic hives. In a study published in February 2015 in the journal Advances in Dermatology and Allergology, a third of chronic hives patients were also infected with H. pylori. What’s more, about 92 percent of those with both hives and H. pylori experienced a reduction in hive-related symptoms after their infection was treated. 2. Working out Could you be allergic to your own sweat? Yes, says Dr. Anand. Although the cause of hives triggered by exercise is sometimes thought to be an increase of body heat, what actually triggers hives when you work out is sweat. Does that mean you should skip exercise if you have chronic hives? Not necessarily. Talk to your doctor if you suspect this may be one of your triggers — he or she may recommend taking a dose of antihistamine just before you exercise to help prevent a flare-up. 3. Stress Research shows that stress can play a major role in many physical and mental illnesses, including chronic idiopathic hives. “Stress can bring on and exacerbate chronic hives,” says Anand. “It’s not uncommon to see chronic idiopathic hives developing following a stressful period of time.” In several studies, people with chronic hives have been found to have higher levels of stress. Researchers have also found a link between post-traumatic stress disorder and hives. To lower stress, try relaxation techniques — for example, mindfulness meditation, which was found to lower the stress hormone cortisol in a study published in 2013 in the journal Health Psychology. 4. Artificial colors and preservatives Hives can be triggered by some food additives, including artificial colors, flavoring agents, and preservatives, according to research published in June 2013 in the Indian Journal of Dermatology. However, food intolerances that trigger hives can’t be tested as easily as typical food allergies, since their underlying mechanism is different. If you suspect that your diet may be a trigger for your hives, your doctor may prescribe an elimination diet, which, over a period of several weeks, will test for a food intolerance. 5. Daylight If sunlight triggers your hives, you’ll probably know within just a few minutes of exposure to one of these three types of light: long-wavelength ultraviolet (UVA), short-wavelength ultraviolet (UVB), and sunlight that doesn’t contain ultraviolet rays, such as sunlight through a window covered with a protective film that blocks UVA and UVB light. Hives triggered by sunlight usually disappear within a day, but in the majority of cases, they recur. Fortunately, sunlight is a rare trigger, and it’s easier to test for than other potential triggers. 6. Cold temperatures Winter is not exactly the most popular season, and with good reason for those who live with chronic hives: The cold can trigger a flare-up in some. Besides the weather, other cold-related triggers include chilly foods and swimming pools. For people who are allergic to the cold, full-body immersion in a swimming pool, in particular, can trigger a severe reaction that involves not just hives but allergic shock (anaphylaxis) and loss of consciousness. Fortunately, it’s easy to find out whether cold is one of your triggers: Your doctor can administer a simple test that involves placing an ice cube on your skin for five minutes to see if a reaction occurs. If it turns out that cold is a trigger for you, your doctor will recommend that you protect your skin from the cold and take your medications as prescribed. 7. An autoimmune disease According to the American Osteopathic College of Dermatology, about half the cases of chronic idiopathic hives are due to immune systems that attack the body’s own tissues (also known as autoimmunity). Thyroid disease is the most commonly reported autoimmune condition in people with chronic hives, followed by rheumatoid arthritis and type 1 diabetes. A study published in September 2013 in the European Journal of Dermatology found that celiac disease is also associated with chronic hives. However, says Anand, “we don’t know if the disease causes urticaria or if the person’s propensity to have an autoimmune reaction causes it. But if we don’t find any triggers when we test for allergens, then we look for an underlying infection or autoimmune disease.” Anand adds that treatment for that condition can help clear the hives. Discovering Your Triggers Other potential triggers of chronic hives include heat and aggravating your skin by scratching it or putting pressure on it (for example, by wearing tight clothes or sitting on a hard surface). Keeping a diary in which you record when and where your symptoms developed or worsened can help you and your doctor find clues and pinpoint your triggers, says Anand. But if even that doesn’t help, don’t lose heart: For most people, even chronic hives whose cause is unknown gradually disappear on their own over time.
