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DENVER — Dermatologists and allergists have sufficient training to handle most cases of chronic urticaria on their own, but a collaborative relationship between these specialists often rapidly resolves many problems in challenging presentations or severe disease, according to a pair who have such a partnership.

“When the diagnosis is unclear, dermatologists have an advantage for ruling out other skin conditions, but allergists often can play a helpful role in identifying triggers,” explained Mark Eliason, MD, Department of Dermatology at the University of Utah, Salt Lake City. 

In addition, they can back one another when patients have concerns that one of the specialists cannot fully resolve. One example is the internet-savvy patient who disputes the diagnosis based on their own preconceptions. A current thorn in the side for both specialists is the patient who cannot be dissuaded from a diagnosis of mast cell activation syndrome (MCAS).

A Referral Can Help Patients Accept Diagnosis

“When patients still are concerned they have MCAS even after I explain why they don’t, a referral to my allergist colleague can be the most efficient way to resolve their doubts,” Eliason said at the Society of Dermatology Physician Associates (SDPA) Annual Summer Conference 2026.

Mili Shum, MD, an allergist at the University of Utah who often collaborates with Eliason, readily agreed. Both Eliason and Shum, who collaborated on an update on chronic urticaria at the meeting, refer patients to each other in cases of a disputed diagnosis. 

Both agreed that referrals for chronic urticaria, which is distinguished from acute urticaria (a condition managed differently) by a duration of at least 6 weeks, are employed selectively, not uniformly. A referral might stem from signs that lead Eliason to suspect an identifiable trigger or unusual features that an allergist might be better suited to evaluate. For Shum, referral might be prompted by unusual signs or symptoms that lead her to suspect other dermatologic disorders might be playing a role.

Experienced clinicians who commonly work up patients for chronic urticaria, Eliason and Shum indicated that their referrals to each other are reserved for those patients with an ambiguous history or with results on standard testing that make a second opinion prudent.

Eliason is particularly likely to refer a patient with urticaria when comprehensive allergy testing is indicated. He and Shum agreed on the criteria. Allergy testing is not helpful in the absence of a consistent trigger, which means symptoms occur within hours in the case of food or environmental exposures. A delay in symptoms can be somewhat longer for drug triggers, but there still needs to be a strong temporal relationship to make testing a viable option. 

The reason is that without a focus for testing, the yield is low, making allergy testing expensive and prone to a high relative risk of both false-positives and false-negatives, Shum agreed. She noted that skin tests and immunoassays are not used interchangeably because of different relative strengths.

Allergy Test Options Differ in Strength

“Skin tests have a higher sensitivity, offer immediate results, and are cheaper, but they require expertise to interpret the results,” Shum said. In contrast, no expertise is required to interpret the results of immunoassays, which are not influenced by the presence of skin disease or current medications. But they are expensive.

In many practices, suspected urticaria leads to excessive and often unhelpful laboratory testing, according to Eliason and Shum. They cited the recently released 2026 international guideline for urticaria, an initiative endorsed by a long list of professional organizations, including the European Academy of Allergy and Clinical Immunology (EAACI), the American Academy of Dermatology (AAD), and the American Academy of Allergy, Asthma & Immunology (AAAAI). Shum said the new guideline now supports “more limited baseline investigations.”

According to the guideline, basic tests include a differential blood count, C-reactive protein levels, and an erythrocyte sedimentation rate. More biomarkers, such as immunoglobulin E and immunoglobulin G levels, can be helpful but depend on patient history and symptom presentation.

“Without clinical evidence supporting a connection, diagnostic tests are not usually beneficial in deducing” the cause of urticaria, Shum said.

Once the diagnosis is reached, the treatment algorithm in the new guideline is straightforward and generally unchanged from previous guidelines, with the exception of the inclusion of the Bruton tyrosine kinase (BTK) inhibitor remibrutinib, which received FDA approval for chronic spontaneous urticaria in October 2025.

The stepwise treatment algorithm begins with second-generation antihistamines, such as cetirizine and fexofenadine, which are less sedating than first-generation agents. If symptom control is not achieved on maximum recommended doses, the next step for most patients is omalizumab, dupilumab, or remibrutinib, which are selected on the basis of comorbidities or patient preferences, such as desire for an oral therapy.

There are multiple further steps in the event of inadequate symptom control, including adjunctive use of second-line antihistamines or immunosuppressive therapies such as methotrexate or mycophenolate. Like the injectable monoclonal antibodies or the oral BTK inhibitor, these are also selected on the basis of presentation and preferences.

Yet, the main message from Eliason and Shum was the value of tackling difficult cases by combining the skills of a dermatologist and an allergist at any point along the arc from diagnosis to treatment. In some cases, this might just involve validating a clinical decision. In others, it might mean a consultation for shared decision-making.

Asked how such a collaboration might be developed by a dermatologist specifically, Eliason told Medscape Medical News that he believes there is value in establishing a relationship with an allergist, as opposed to referring to a department or a clinic.

“If you have someone with whom you can easily communicate, you will both be able to help each other with difficult cases,” advantages that extend to both specialists and their patients, he said. 

Eliason reported no relevant financial relationships. Shum reported financial relationships with Allakos, AstraZeneca, and GlaxoSmithKline.