Chronic Spontaneous Urticaria – CSU
Chronic spontaneous urticaria (CSU) is a condition that causes recurring hives and swelling without a clear or predictable trigger. It is also called chronic idiopathic urticaria.
The itchy, raised welts can appear suddenly and last for weeks or even months. While CSU can be frustrating and uncomfortable, treatments are available to help control symptoms and improve quality of life.
What is urticaria?
Urticaria (pronounced ur·tuh·keh·ree·uh) is another word for hives. It’s estimated that 20% of people in the United States will develop hives at some point in their lives. The development of hives is sometimes related to an allergic reaction, usually to pollen, pet dander, certain foods, insect venom or medications. Hives can also be triggered by viral infections or physical stimuli such as temperature changes, pressure on the skin, or exercise.
What is chronic spontaneous urticaria (CSU)?
Some people develop hives in which symptoms come and go for six or more weeks. This is known as chronic hives or chronic urticaria. When you and your doctor are unable to identify what’s causing your hives to keep coming back or occur on different parts of the body, it’s called CSU or chronic idiopathic urticaria. Idiopathic means “of unknown cause.”
CSU outbreaks can appear at any time without triggers. The hives are not contagious. Symptoms of CSU are not life-threatening, buy they can cause extreme discomfort and impact quality of life.
How common is CSU?
CSU affects approximately 1.6 million people in the United States. It most often occurs in people between the ages of 20 and 40. Women are twice as likely to have CSU than men.
What causes CSU?
CSU is caused by the release of histamine and other chemical mediators, usually after exposure to an unknown trigger. When this histamine release happens in the outer layers of the skin, it results in hives.
Most of the time, it is a case of acute hives, which can resolve quickly. But in some people, the hives can become chronic when they last more than six weeks. Chronic hive symptoms may also come back repeatedly.
Treatment options are available for acute and chronic urticaria. It is best to see a board-certified allergist trained in immunology or a dermatologist.
How is chronic spontaneous urticaria diagnosed?
When you and your doctor are unable to identify what’s causing your chronic hives, it’s likely chronic spontaneous urticaria.
On your first visit to the doctor, you may be asked the following questions to try to pinpoint what’s causing the hives:
- When and where on the body do hives occur?
- Is there any swelling?
- How long do symptoms last?
- What were you doing at the time hives occurred?
- What medications (if any) are you taking?
- Are there any other symptoms?
Your doctor may also ask what foods you were eating at the time of symptoms to determine if a food allergen caused your hives.
A blood test can help with diagnosis since blood cells in CSU patients often manufacture high levels of histamine.
How is chronic spontaneous urticaria treated?
CSU is not a life-long condition. It usually goes away by itself over a period of days, weeks or months. Meantime, doctors and patients can work together to find the most appropriate treatment and symptom management strategy.
CSU guidelines recommend a step-based approach to treatment. It starts with over-the-counter antihistamines, preferably non-sedating ones. (Since CSU is a whole body condition, topical skin creams are not considered a treatment.)
If antihistamines do not help, then H2 blockers are the next step. These block production of the histamine that causes hives. Doctors might also consider montelukast, which blocks leukotrienes, a chemical involved in inflammation.
Advanced medications include the biologics omalizumab (Xolair) and dupilumab (Dupixent). Both are given by injection once a month. Omalizumab and dupilumab treat physical and chronic urticaria when antihistamines have not worked. Omalizumab helps prevent histamine release while dupilumab blocks eosinophils, stopping skin symptoms before they can start.
A Bruton’s tyrosine kinase (BTK) inhibitor is a class of medication specific to patients with CSU. Remibrutinib (Rhapsido®) is thefirst BTK inhibitor to treat the condition. It works by blocking or slowing a protein that causes the release of histamine. BTK inhibitors may be recommended by your doctor when your current CSU medicine is not controlling symptoms.
What are the impacts of chronic spontaneous urticaria on quality of life?
It is important to understand the impact that CSU can have on quality of life. The burden of physical urticaria can be significant. Some people with CSU describe the random episodes of extremely itchy skin or painful skin as feeling like a poison ivy sensation or wanting to scratch their skin off.
Itchy hives symptoms can leave people dealing with CSU in constant pain and fatigued. It can cause difficulty getting to sleep or staying asleep. Many people develop anxiety and depression as well.
People with CSU are often frustrated by the unknown nature of this disease. They may also feel socially stigmatized as their skin may look “diseased.” This may cause them to avoid social situations. The costs of healthcare for CSU as well as potential loss of work productivity can further add to the burden.
A 2017 study identified different stages of the journey for patients living with chronic spontaneous urticaria.
- The first stage is the crisis stage where symptoms develop. Chronic urticaria patients may have feelings of torment, disorientation and shock due to the nature of the symptoms.
- The next phase involves searching for answers. Patients begin making repeat visits to doctors and even doing their own research.
- The third phase is when the condition is diagnosed. This may provide some hope and relief, as patients begin to connect with others who have CSU. But many patients still experience anxiety and struggle with the unknown cause of the skin disease.
- The last phase involves disease management. Patients learn to live with the disease – but this can depend on how effective the treatment is and if there are recurrent symptoms.
What can healthcare professionals do to be most helpful to people with CSU?
Healthcare professionals should listen and strive to understand patients’ experiences. Recognize the different phases of their journey.
CSU patients need to feel that their doctors are taking them seriously. Acknowledge how CSU affects quality of life and involve patients in deciding on treatment.
Ongoing research into the psychosocial impacts of chronic urticaria will help bridge gaps in care. It will also assure the needs of CSU patients are more fully addressed.
Reviewed by:
Purvi Parikh, MD, FACAAI is an adult and pediatric allergist and immunologist at Allergy and Asthma Associates of Murray Hill in New York City. She is on faculty as Clinical Assistant Professor in both departments of Medicine and Pediatrics at New York University School of Medicine.
