Something New Under the Sun: Sunscreen Allergies and Irritancies

Selected by Pietro Cazzola

SunscreenSunscreen use has increased dramatically. More than 85% of European dermatology patients use these photoprotective agents. Sunscreens are used alone but are also found in make-up and emollients, hair sprays, and shampoos. The same chemicals are incorporated into manufactured products and magazine ink to protect against photodegradation. These authors reviewed the literature and found 306 English-language reports evaluating adverse sunscreen effects.
Key points: Most sunscreen adverse effects are irritant, allergic, phototoxic, or photoallergic contact dermatitis. Almost all photo-induced reactions are provoked by UVA radiation. Phototoxic and irritant reactions to sunscreens are more frequent than allergic and photoallergic reactions. Allergic reactions have been reported in <1% of individuals referred for patch testing, but this prevalence is likely underestimated. Risk factors for allergic sunscreen reactions include preexisting photodermatoses, application to inflamed skin, atopic dermatitis, and outdoor professions. Benzophenone-3 (oxybenzone) and benzophenone-4 (sulisobenzone) protect against UVB and UVA II. Other benzophenones are used as UV filters, not only in sunscreens but also in ink, textiles, paints, plastics, and rubber products to prevent sunlight bleaching. Benzophenone-3 causes >70% of sunscreen contact and photocontact allergies. It cross-reacts with another sunscreen agent, octocrylene, and the nonsteroidal anti-inflammatory drug ketoprofen. Cinnamate sunscreen compounds are uncommon causes of contact allergy and photoallergy but do cross-react with flavorings and fragrances. Physical blockers — zinc oxide and titanium dioxide — are nonirritating and do not cause allergies or photoallergies; they are a good option when chemical UV blockers are contraindicated.

Heurung AR et al. Adverse reactions to sunscreen agents: epidemiology, responsible irritants and allergens, clinical characteristics, and management. Dermatitis 2014 Nov/Dec; 25:289. (http://dx.doi.org/10.1097/DER.0000000000000079) -