What Is Ultraviolet (UV) Light Allergy?

In daily life, many people develop small papular rashes and erythematous patches on sun-exposed areas—such as the face, neck, or arms—when the weather warms up in spring or approaches summer. These lesions are often accompanied by intense pruritus (itching). Notably, if adequate sun protection measures are taken during this period, such symptoms typically do not occur. This condition is closely associated with ultraviolet (UV) radiation exposure and is commonly referred to as “UV allergy” or photosensitivity. But what exactly is UV allergy? The following section provides a detailed explanation.

What Is UV Allergy?

UV allergy—clinically termed photodermatitis—is a group of skin disorders triggered by an abnormal immune response to ultraviolet radiation. It typically manifests after sun exposure, presenting as pruritic, acute-onset rashes predominantly affecting sun-exposed areas. Following UV exposure, affected individuals commonly develop papules, vesicles, and intense itching. Lesions most frequently appear on the face, neck, the “V”-shaped area of the anterior neck, dorsum of the hands, and extensor surfaces of the upper limbs. Therefore, reinforcing protective measures for exposed skin—especially avoiding excessive sun exposure—plays a crucial role in preventing UV allergy. Individuals with highly sensitive skin should avoid short-sleeved clothing and instead opt for long sleeves to provide physical coverage. In severe cases, medical consultation with a dermatologist is strongly recommended.

Knowledge Extension: How to Manage UV Allergy

1. General Management

Avoid contact with known photosensitizing substances and discontinue any medications that may induce photosensitivity. Strict photoprotection is essential—including consistent use of broad-spectrum sunscreen, protective clothing, and wide-brimmed hats. Patients with severe disease should avoid fluorescent lighting and prefer incandescent bulbs whenever possible. Oral supplementation with B-complex vitamins (e.g., vitamin B complex) may serve as adjunctive therapy to alleviate pruritus. For more severe cases, immunosuppressive agents—including tripterygium preparations, azathioprine, and cyclosporine—may be prescribed under medical supervision.

2. Pharmacologic Treatment

Antiphotosensitivity agents constitute the cornerstone of pharmacologic management and include nicotinamide and hydroxychloroquine, primarily used to treat UV-induced cutaneous damage. Antihistamines—both second-generation (e.g., loratadine, mizolastine, cetirizine) and first-generation (e.g., ketotifen, doxepin)—help suppress histamine release and relieve pruritus, thereby controlling clinical symptoms. In patients with more severe manifestations, combination therapy with multiple agents may be warranted.

The above outlines what UV allergy is and how it can be managed. We hope this information proves helpful to you.