The cause of most cases of solar urticaria is the patient’s sensitivity to sunlight.
Sunlight exposure to the skin leads to activation and degranulation of a variety of inflammatory cells within the skin, such as mast cells, and the release of chemical mediators with inflammatory activity, including histamine, 5-hydroxytryptophan, cytokines, chemokines, and metabolites of arachidonic acid (e.g., prostaglandins and leukotrienes), which cause vasodilatation and an increase in vascular permeability, leading to the development of urticaria-like skin lesions.
Typical symptoms of solar urticaria are itchy erythema and urticaria-like rash on exposed areas after sun exposure. The wavelengths that cause solar urticaria allergy are mostly below 370nm, and factors such as surgery, mosquito bites and infections are triggering factors for solar urticaria.
It is recommended that patients with solar urticaria seek professional medical attention in a timely manner, so as not to delay their condition.