Urticaria, more commonly called hives, can be acute or chronic, depending on how long symptoms last. Chronic urticaria can be treated with medication, and some people experience remission after 1 year.
“Urticaria” is the medical term for hives, which about 1 in 5 people experience at some point in their lives. These raised, itchy bumps can come and go periodically — typically in response to some kind of trigger — or may be longer lasting.
Chronic (long lasting) hives are often different from acute (short-term) hives in terms of their causes and treatment. Understanding these differences can have important implications for finding relief.
Here, we answer some of your frequently asked questions about the differences between chronic urticaria and acute hives and how to tell the difference.
What is the difference between chronic urticaria and urticaria?
Urticaria can be classified as either acute or chronic based on how long the symptoms last. Acute urticaria generally lasts less than 6 weeks .
Chronic urticaria lasts longer. Medically, it is defined by hives or welts (which are sometimes called wheals) that last at least 6 weeks. The hives may occur daily or almost every day, or they may come and go periodically during this time.
What is the main cause of chronic urticaria?
Urticaria is caused by an overactivation of your immune system and the release of itch-signaling molecules in your skin. These itch mediators, which include molecules such as histamine, can increase the activity of immune cells and activate sensory nerves within your skin. This leads to the inflammation and itch that commonly occur with hives.
A variety of factors can trigger this activity. For instance, some cases of chronic urticaria may be triggered by pressure, friction, or scratching, while others may be triggered by cold or heat. Exercise-induced urticaria is also common .
Other types of health conditions, including some autoimmune conditions, thyroid disorders, skin infections, and some forms of cancer, can also cause chronic hives.
However, in most cases, the cause of chronic urticaria is not known. Healthcare professionals refer to this as chronic idiopathic urticaria or chronic spontaneous urticaria (CSU).
What is the difference between chronic spontaneous urticaria and skin allergic reactions?
Both CSU and allergic skin reactions result from inflammation in your skin that causes swelling and itchiness.
In the case of an allergic reaction, specific triggers lead to the development of hives. Common allergenic triggers for hives include:
- certain foods, such as peanuts, eggs, or shellfish
- some medications (especially penicillin)
- latex
- pet dander
- pollen or plants
If chronic urticaria is the result of an allergic reaction, avoiding the trigger can help prevent hives from developing.
With CSU, there is no known trigger. This can make the condition more difficult to manage and can lead to more severe symptoms. In one study involving 500 people with CSU, nearly half of the participants had symptoms that were classified as moderate to severe. People with CSU may also be more likely to describe their hives as painful rather than itchy.
Other types of allergies are common among people with CSU, and this can further complicate the diagnosis.
How do I know if my hives are autoimmune?
Although the precise cause of CSU has not been identified, there is evidence to suggest that it’s a result of autoimmune activity. Scientists believe swelling, itchiness, and pain develop as a result of the overactivation of mast cells in the skin. This promotes the release of molecules that trigger inflammation and nerve activation in the absence of an external trigger.
When trying to determine the cause of hives, your doctor will obtain your medical history and conduct a physical examination to see whether they can identify a trigger. If they cannot, they may order certain types of blood tests to check for evidence of autoimmune activity.
These tests may include:
In general, a high ratio of anti-TPO antibodies to total IgE is considered a strong marker for chronic urticaria caused by autoimmunity. Basophil activation tests can provide additional support as needed. Your doctor may give you further testing to rule out other potential causes of chronic hives.
Does CSU ever go away?
Although CSU, by definition, lasts longer than acute hives, it’s not necessarily permanent. Data suggest that about one-third to one-half of people who experience CSU will have a spontaneous remission of symptoms within 1 year.
Other people may find relief through medications. Management of CSU typically involves a stepwise approach based on symptoms and response, in which a more conservative approach is used at the start and medications are added or escalated if necessary.
Antihistamines are usually some of the first medications used. If symptoms don’t respond to these medications, biologic therapy or immunosuppressants (cyclosporine) may be used as well or instead.
Omalizumab (Xolair) is currently the only biologic therapy approved for the management of CSU. In clinical studies, more than half of participants treated with omalizumab had a significant and meaningful improvement in CSU symptoms within 12 weeks, and an even greater number saw symptom improvement after a step up in dosing.
Other biologics currently being studied for treatment of CSU include:
The takeaway
CSU can be frustrating and painful as you work with healthcare professionals to try to identify a potential cause of your symptoms. Unlike acute or chronic hives, CSU has no known trigger. The painful itching and inflammation it causes are instead thought to result from autoimmunity in your skin.
Understanding the differences between acute hives and CSU can help you make decisions about treatment. If you’re experiencing hives that have lasted longer than 6 weeks without an obvious cause, healthcare professionals can help determine whether you have CSU and what steps you can take to find relief.
Most Popular
Comments / 0