About 20% of Americans will experience hives (urticaria) at some point, but for some people, the bumps and itchiness can last for more than six weeks and continue for years. If you have chronic hives, it’s important to work with an allergist to identify your triggers so you can avoid them. Being aware of your body’s reaction to certain weather conditions can provide important clues to clearing up your hives.
Hives and Heat
Some people develop hives when they get hot or sweaty. Too much sun, exercise, hot baths or showers, hot blow dryers or heaters, and even feeling angry can bring on hives. This type of hives is called heat urticaria (HU), and it’s rare. If you do have HU, your hives will likely occur within minutes of exposure to heat or sweat and last for an hour or two. You may also experience additional symptoms, including headache, weakness, nausea or wheezing.
Start tracking when you’re exposed to heat and when hives develop to see if there’s a connection. Your doctor may also perform a test where heat is applied to your skin to see if it triggers hives. If it does, hives usually appear within a few minutes.
Hives and Cold
Hives can also be triggered by being outside in cold weather, breathing cold air, or swimming in cold water. This type of hives is called cold urticaria (CU), and there are two varieties of it: acquired and hereditary. If your hives occur within minutes of contact with the cold, it’s likely acquired cold urticaria. If it takes hives a day or two to appear, it’s likely hereditary cold urticaria. Both types can last for up to two days. You may have additional symptoms, including headache, fever, fatigue, or anxiety. Like heat urticaria, cold urticaria is rare.
Your doctor may give you an ice cube test to help determine if you have it. The test involves putting an ice cube on your skin for four to five minutes, then removing it to see if a hive forms within the next 10 minutes. If a hive doesn’t appear, and cold urticaria is still suspected, your doctor may recommend another test where you’re exposed to cold air for 20 to 30 minutes.
Hives in All Weather
You may discover that neither heat nor cold seem to trigger your hives. Other triggers to explore with your doctor include allergies to:
- Bug bites and insect stings
- Certain foods like nuts, eggs, shellfish, or chocolate
- Specific medications like aspirin, ibuprofen, penicillin, and sulfa
- Irritants in the environment like pollen and pet dander
For most people with chronic hives, the trigger can’t be pinpointed. Their hives are considered idiopathic, meaning they don’t have an identifiable cause. However, the cause doesn’t need to be determined to get effective treatment for clearing up hives. Whether the cause of hives is known or unknown, doctors traditionally prescribe antihistamines or other medications to relieve itching and treat the underlying problem.
