Chemical UVA sunscreen/sunblock: Ecamsule (Mexoryl SX)

Generic name: Ecamsule; terephthalylidene dicamphor sulfonic acid

Brand(s): Mexoryl

Type: Chemical

Range of UV spectrum covered: UVA (both UVA-1 and UVA-2)

Wavelengths covered: 290-400 nm, which covers all of UVA and even part of UVB; peak protection at 345 nm

Stability:
Ecamsule is stable when exposed to sunlight, which is an advantage over the widely used chemical UVA blocker avobenzone.

Summary:
Ecamsule is one of the very few chemical sunscreens with good coverage of the entire UVA spectrum. Furthermore, it does not degrade under sunlight and is not significantly absorbed into the skin. Overall, it appears to have a good safety profile, even though long-term human safety studies are lacking.

Details:
Ecamsule is an organic chemical agent capable of absorbing light throughout the entire UVA spectrum. It is one of the very few comprehensive UVA sun blocks in widespread use. It has an important advantage of being photostable, i.e. it does not degrade and lose effectiveness on exposure to sunlight.

Ecamsule was patented by L'Oreal as Meroxyl SX. Its other widely used relative is Mexoryl XL (drometrizole trisiloxane). Mexoryl SX is water soluble and Mexoryl XL - oil soluble. When combined, Mexoryl SX and Mexoryl XL provide synergistic UVA protection.

Ecamsule appears to be relatively safe because is only minimally absorbed into the skin or systemic circulation. Since ecamsule is stable, toxicity of degradation products is not a concern. Animal and cell culture studies indicate the lack of mutagenic and carcinogenic effects. However, direct safety studies of long-term topical use in humans are lacking. Rarely, ecamsule may cause skin arritation/dermatitis. In its pure form, ecamsule is acidic. In commercial products, it is neutralized by organic bases, such as mono-, di- or triethanolamine. Ethanolamines sometimes cause contact dermatitis. If you develop reaction to a sunscreen with ecamsule, the culprit might be the neutralizing base rather than ecamsule itself. You could try a brand with a different neutralizing base.