Stepwise treatment is the best way to manage solar urticaria, a rare but disabling photodermatosis mediated by immunoglobulin E (IgE), according to a systematic review and meta-analysis in the Journal of Clinical Medicine.
A group led by Maya Engler Markowitz, MD, a dermatologist at Rabin Medical Center in Petah Tikva, Israel, concluded that therapy should begin with high-dose H1 antihistamines, with the addition of leukotriene receptor antagonists if necessary. If these are ineffective, the next steps are phototherapy and immunotherapy with a biologic.
Though its exact prevalence is unknown — a recent study found its occurrence to be rising in the US, particularly in children. Solar urticaria can significantly impair quality of life and severely limit daily activities. It is estimated to be involved in just 4%-8% of photodermatosis cases and 0.4% of all urticaria cases.
Symptoms are reproducibly triggered by specific wavelengths of radiation, most commonly within the ultraviolet A and visible light spectra, as determined by phototesting.
Most therapeutic data derive from observational studies, small series, and case series, said Engler Markowitz. “Given the need for structured treatment guidelines, we chose to conduct a comprehensive literature review and meta-analysis,” she told Medscape Medical News.
“Although it’s considered a rare disorder, in our tertiary medical center, with a dedicated photodermatoses clinic, we encounter a considerable number of affected patients. Our clinical experience further underscores the need to establish a structured therapeutic approach.”
As to patient characteristics, the study found a slight predominance of women but no established familial or ethnic risk factors. “The disease usually appears as an isolated, acquired photodermatosis,” Engler Markowitz said.
She added that solar urticaria has been reported in association with atopic diathesis and other allergic diseases such as asthma and eczema, as well as other forms of urticaria. “It’s not considered a risk factor for cutaneous malignancy, and although no numerical data are available, it can be expected that sun avoidance due to the desire to prevent flares may in fact reduce the risk.”
Study Details
Conducted in May 2025, the literature search included retrospective or prospective studies, case series, and analytical studies such as comparative cohort studies and randomized controlled trials.
Antihistamines
Out of 38 eligible papers, 21 evaluated antihistamines (376 patients) and showed a pooled response rate (partial or complete) of 83% (95% CI, 70.4%-91.1%) and a complete response rate of 7.7% (95% CI, 1.7%-28.3%).
Phototherapy
The 11 studies (145 patients) assessing ultraviolet B phototherapy showed a similar overall response of 89.8% (95% CI, 77.9%-95.3%) but a higher complete response rate of 39.8% (95% CI, 18.3%-66.1%). “Phototherapy may be considered as a first- or second-line option when available and feasible,” the authors said.
Omalizumab
In nine studies (76 patients), the anti-IgE monoclonal antibody omalizumab (Xolair), given every 2-4 weeks at doses ranging from 150 to 600 mg, was the most effective, with 93.2% (95% CI, 73.8%-98.5%) achieving some response and 68.4% (95% CI, 48.5%-83.2%) reaching complete remission.
Intravenous Immunoglobulin (IVIG)
Two studies of severe refractory disease looked at IVIG. A prospective phase 2 multicenter trial of nine patients reported at least partial response in six. A retrospective seven-case series reported a response in five. Most patients required additional therapies such as phototherapy or antihistamines.
Cyclosporine
Cyclosporine was evaluated in a single retrospective case series involving 11 patients with severe treatment-resistant solar urticaria. Only two patients showed clinical improvement, and five had adverse events leading to treatment discontinuation in one case.
Plasmapheresis
Evidence for plasma treatment was limited to an older case series of three patients. One achieved complete remission, another showed a transient clinical improvement, and the third had no response.
Commenting on the study but not involved in it, Adam Friedman, MD, FAAD, chair of Dermatology and director of Translational Research at The George Washington University School of Medicine and Health Sciences in Washington, DC, agreed that antihistamine therapy is the first step.
But after giving four times the recommended dose of second-generation nonsedating antihistamines with no relief, “my go-to is hydroxychloroquine,” he told Medscape Medical News. “Cyclosporine works fast, but you can’t stay on it long [owing to side effects]. The European guidance says no longer than 6 months.”
Even a partial response may suffice to restore daily functioning and improve quality of life, the authors stated. “Therefore, given their favorable safety profile, ease of administration, and wide availability, antihistamines remain a rational initial approach.”
Although solar urticaria’s relative rarity limits the feasibility of large-scale clinical trials, Engler Markowitz said, “Given the significant impact of solar urticaria on quality of life and its association with other forms of urticaria, we believe that ongoing active research is well justified.”
This research received no external funding. The authors and Friedman disclosed having no relevant conflicts of interest.