Benzophenones are ultraviolet light filters that have been documented to cause a myriad of adverse cutaneous reactions, including contact and photocontact dermatitis, contact and photocontact urticaria, and anaphylaxis. In recent years, they have become particularly well known for their ability to induce allergy and photoallergy. Topical sunscreens and other cosmetics are the sources of these allergens in most patients, but reports of reactions secondary to use of industrial products also exist. Benzophenones as a group have been named the American Contact Dermatitis Society's Allergen of the Year for 2014 to raise awareness of both allergy and photoallergy to these ubiquitous agents.

Sunscreen is a key component in the preventive measures recommended by dermatologists and public health campaigns aimed at reducing sunburn, early skin aging, and skin cancer. To maximize compliance, adverse reactions to sunscreens should be minimized. Although inactive ingredients cause many of these reactions, it is important for dermatologists to be aware of reactions to active ultraviolet filters. There are approximately 120 chemicals that can function as ultraviolet (UV) filters. This review focuses on the 36 most common filters in commercial and historical use. Of these, 16 are approved for use by the US Food and Drug Administration. The benzophenones and dibenzoylmethanes are the most commonly implicated UV filters causing allergic and photoallergic contact dermatitis (PACD) reactions; benzophenone-3 is the leading allergen and photoallergen within this class. When clinically indicated, patch and photopatch testing should be performed to common UV filters.