NEW YORK — The responsibility for diagnosing and treating chronic spontaneous urticaria (CSU), for which there is a newly approved drug, should be in the hands of dermatologists who have the skills, tools, and experience to intervene more quickly and in a broader range of skin types than allergists.

A disease of mast cell activation in the skin, urticaria is a clinical diagnosis that does not require a complicated search for triggers, and dermatologists are better trained to differentiate this disease from other skin disorders, according to Mona Shahriari, MD, who is an associate clinical professor of dermatology at Yale School of Medicine, Yale University, New Haven, and practices in Avon, both in Connecticut.

“With the expanding CSU toolbox, now is the time for dermatology to take back ownership of this skin disease in order to optimize patient outcomes,” Shahriari said.

Speaking at the Skin of Color Update (SOCU) 2025, Shahriari spoke about urticaria in general but underlined the unmet needs in patients with different skin types, particularly darker skin tones.

Diagnosis Even Further Delayed in Skin of Color

On average, patients with CSU are symptomatic for more than 2 years before being accurately diagnosed, but the problem is greater in patients with darker skin types, a group also slow to receive the most effective therapies, Shahriari said.

Distinct from acute urticaria, a disease of hives that typically flares intermittently for no more than 1 or 2 weeks, CSU is defined by skin flares or other symptoms that persist for more than 6 weeks. Shahriari conceded that the 6-week delineation is somewhat arbitrary but is nonetheless used for distinguishing a chronic from an acute presentation.

An inflammatory pruritic condition, CSU is idiopathic, rather than inducible with a known trigger, in approximately 80% of cases. Erythema with raised wheals on the skin is typical; angioedema and wheals may occur together or separately. All forms of urticaria — acute or chronic — are driven by mast cell activation and degranulation.

The challenge of recognizing CSU in darker skin — which is at least as prone or, according to one study Shahriari cited, more prone to CSU — is that the erythema “may be difficult to appreciate on melanin-rich skin.” Even textbook images do not consistently capture the appearance.

In addition, the associated skin elevation is less distinct and often requires palpation. In some cases, side lighting may help as do videos, which often better delineate the change in color and skin texture than a still photograph, according to Shahriari.

Regardless of skin type, the misperception that urticaria requires complex laboratory work to isolate triggers is likely to be one reason some dermatologists have been slow to pursue diagnosis and treatment. The opposite is true, she said.

“The guidelines recommend against extensive initial testing,” said Shahriari, citing allergist guidelines to make this point. Although basic labs, such as a complete blood count with differential and an erythrocyte sedimentation rate, are reasonable, she called CSU a clinical diagnosis informed by history.

The reasons for the delay in diagnosis are common to those with all skin types. The intermittent signs and symptoms, which often have an uncanny tendency to resolve just prior to a clinical examination, is one. Another is that patients, rather than receiving a definitive diagnosis, are often cycled through courses of antihistamines and steroids for extended periods before being switched to a therapy with a sustained effect.

This is problematic because it unnecessarily delays the highly targeted therapies patients need when antihistamines are inadequate. The anti-immunoglobulin E monoclonal antibody omalizumab was a breakthrough drug for CSU when it was approved in 2014. It was joined earlier this year by dupilumab, an inhibitor of interleukin (IL)-4 and IL-13 signaling, in children aged 12 years or older who remain symptomatic despite treatment with antihistamines, but now — as of September 30, 2025 — there is a third targeted agent.

New Oral Targeted Therapy for CSU

The Bruton tyrosine kinase inhibitor remibrutinib was approved just days before Shahriari spoke at the SOCU meeting. This is an oral pill that is taken twice daily. In the pivotal trial published earlier this year, about 50% achieved good control within 12 weeks, according to Shahriari, who said response rates climbed with longer treatment.

There is concern that clinicians have been slow in taking the next step from antihistamines to the more effective agents and the reason is unclear, but Shahriari speculated that the anaphylaxis black box warning for omalizumab gave pause to at least some clinicians who have hesitated to step up from antihistamines.

Allergists who use this drug for other indications, and are perhaps more comfortable with an anaphylactic reaction, appear to prescribe this more for CSU, but Shahriari said the risk is low overall and anaphylaxis has never been seen in a clinical trial of omalizumab for CSU.

In her own practice, she takes responsibility for injecting the first three doses, when risk is the highest, before prescribing the drug for at-home use. She also sends patients home with an EpiPen, although she is not aware that one has been used by her patients.

There are several additional targeted agents, including several JAK inhibitors, that have reached late stages of clinical testing for CSU, so Shahriari emphasized that treatment options appear likely to expand. However, her larger point was that existing drugs might not be used often enough, particularly in patients with darker skin types.

In addition to encouraging dermatologists to improve their skills of diagnosing CSU in patients of all skin types, Shahriari called for a “low threshold” for moving to the more targeted therapies in patients of all skin types who have tried and not achieved adequate control on the first line therapies.

Raj Chovatiya, MD, PhD, clinical associate professor of medicine, Chicago Medical School, Rosalind Franklin University, North Chicago, agreed with the premise that CSU is a dermatologic disorder for which care by a dermatologist makes sense.

Even if there are triggers for CSU in a small proportion of patients, often identifiable by history, many dermatologists appear to be misinformed that there is a need for a complex workup or that the therapies are not ones they use routinely, he told Medscape Medical News.

“We have experience with related disorders and with the treatment options used for CSU,” said Chovatiya, who sees no reason to hesitate to initiate treatment with antihistamines or to step up to a targeted therapy if adequate control is not achieved.

“The risk of anaphylaxis with omalizumab is very low for CSU, and it should not be considered to be a big issue with routine precautions,” he said, citing Shahriari’s strategy of administering the first few doses under observation.

For those dermatologists not treating CSU, it is a good time to start, and now with additional targeted therapies, the opportunities for treatment success have been increased, he added.

Shahriari reported having financial relationships with AbbVie, Amgen, Apogee, Arcutis, Bristol Myers Squibb, Dermavant, Galderma, Incyte, Janssen, Leo, Lilly, Novartis, Pfizer, Regeneron, Sanofi, Takeda, and UCB. Chovatiya reported having financial relationships with AbbVie, Acelyrin, Alumis, Amgen, Apogee, Arcutis, argenx, Astria, Avalere, Beiersdorf, Bristol Myers Squibb, Cara, Castle, Celldex, CLn Skin Care, Dermavant, EMD Serono, Formation Bio, Galderma, Genentech, Incyte, Johnson & Johnson, Kenvue, Leo, Lilly, L’Oreal, Nektar, Novartis, Pfizer, RAPT, Regeneron, Sanofi, Sitryx, Takeda, TRex Bio, UCB, and Zai Lab.