Chronic hives (urticaria) are itchy patches on your skin that last for six weeks or more. Oftentimes these long-lasting hives don’t have a clear cause, which can make the diagnostic process complicated.
Unfortunately, there’s no singular test doctors can use to confirm whether someone has chronic hives. Instead, diagnosis happens through a process of elimination, looking at what may or may not be causing your hives.
If someone has acute hives, meaning they last for less than six weeks, the cause is usually easier for doctors to identify. Acute hives are often triggered by illness or some kind of allergic reaction to food or medication.
But chronic hives last for more than six weeks and can persist for years. The symptoms—raised welts that move around the body over time—may resemble those caused by food allergies, infections, or other skin conditions, but the underlying issue is oftentimes hard to pin down.
Finding the Root Cause Can Be Difficult
There are two causes of chronic hives (urticaria):
- Inducible: Chronic inducible urticaria is set off by something specific. Triggers can include sunlight, water, pressure or vibration on the skin, exercise, and temperature changes.
- Spontaneous: Chronic spontaneous urticaria (CSU) has no identifiable external cause. Evidence suggests that these cases are often caused by autoimmune reactions, where the body mistakenly produces infection-fighting antibodies against its own cells. While the root cause is internal, stress, nonsteroidal anti-inflammatory drugs (NSAIDs) like aspirin, and hormonal changes can cause a flare-up of symptoms.
If someone appears to have chronic hives, their doctor may ask them to keep a diary for several weeks to see if their symptoms have an external trigger—if someone notices a pattern, they likely have inducible chronic hives.
But up to 90% of people with chronic hives have the spontaneous variety, meaning they won’t be able to identify what’s setting off their symptoms. This makes finding answers extremely challenging.
A care team of primary care doctors, allergists, immunologists, or dermatologists often uses the following step-based process to diagnose someone with chronic hives:
- Find out if hives are chronic or acute: Doctors will review a patient’s medical history and look at their skin. If someone has had daily or almost daily hives for six weeks or more, then they have chronic urticaria. Doctors may also try to determine if food allergies, drug allergies, or infections are at play, which would make someone’s case acute rather than chronic.
- If hives are chronic, determine if they’re spontaneous or inducible: If someone’s hives are chronic, their doctor will need to determine if there’s a specific external trigger. This could include asking questions about when patients are noticing their hives (after a hot shower or after being in the sun, for example), or asking patients to keep a symptom diary.
- Rule out underlying causes: If a person’s symptoms don’t seem to be caused by an external trigger, doctors may perform other tests to rule out other conditions, including a complete blood count to check for infection or anemia, or inflammation tests. They may also test thyroid function, since thyroid disorders are sometimes associated with chronic hives. If no underlying cause is found, the patient may have chronic spontaneous urticaria.
Though patients can undergo testing to learn more about what may be triggering their chronic spontaneous urticaria (CSU), it’s not often recommended. That’s because this extensive laboratory testing is expensive and doesn’t appear to lead to better outcomes.
Though getting a chronic hives diagnosis can be challenging and time-intensive, there are treatment options available once you are diagnosed.
For people with chronic inducible hives, specialists will provide more information on how to avoid and mitigate those triggers. Anti-histamines and other medications are also available to minimize symptoms.
With chronic hives that have no clear cause, medications are the primary line of defense. People with chronic spontaneous hives are usually given antihistamines to start. But if the antihistamines don’t improve symptoms, treatment can be ramped up to include omalizumab or dupilumab. Both of these drugs help regulate the body’s immune system and block inflammation.
There’s no cure for chronic hives, but the vast majority of cases resolve on their own within five years.
