Science
Mechanism of Action
This ingredient functions by absorbing UVB radiation, with a peak absorption at 289 nm, and subsequently converting this harmful energy into less damaging infrared heat. This process aims to diminish the penetration of UVB light into the epidermis, however, it provides no protective action against UVA wavelengths.
Research
Clinical Evidence
Low confidenceN/A
Key findings
- 01 At its maximum approved concentration of 3% in the US, cinoxate contributes a mere 1-2 SPF units, establishing it as one of the weakest approved sunscreen ingredients.
- 02 Cinoxate is susceptible to photodegradation under UV exposure, leading to a rapid decline in its protective capacity and the potential formation of unknown degradation products, necessitating frequent reapplication.
- 03 In vitro studies using Chinese hamster ovary cells suggest that cinoxate, when exposed to UV light, may inhibit DNA excision repair by enhancing sister-chromatid exchanges.
Transparency
Dusting Analysis
Cinoxate is not typically 'dusted' in formulations; rather, it is an active ingredient whose inherent limitations and low efficacy make its continued use questionable despite its regulatory approval in some regions.
The Formula
Formulation
Stability
As a cinnamate ester, cinoxate exhibits poor photostability, degrading under UV light. This degradation not only diminishes its sun-protective capabilities but can also lead to the generation of unidentified byproducts. Such instability necessitates frequent reapplication when used in sun-protective products, and even advanced encapsulation techniques have shown limited success in fully mitigating its rapid efficacy decline after sunlight exposure.
Conflicts
- Photodegradation under UV exposure, leading to a loss of protective capacity and potential formation of unknown degradation products.
Safety
Safety Profile
The US FDA has categorized cinoxate as 'Category III' for sunscreen active ingredients, indicating insufficient data to classify it as Generally Recognized as Safe and Effective (GRASE). Its safety review by the Cosmetic Ingredient Review (CIR) Expert Panel remains deferred due to its OTC drug monograph status. Cinoxate is not approved for use in sunscreen products in the EU, Australia, or Japan. It is likely absorbed through the skin, although no specific FDA absorption studies are available. The in-vitro finding of inhibiting DNA excision repair after UV exposure raises significant safety questions.
Your Skin
Skin Compatibility
Our Assessment
Verdict
Cinoxate offers minimal sun protection, suffers from poor photostability, and carries significant safety and regulatory concerns, making its inclusion in precision skincare formulations ill-advised.
Related
Similar Ingredients
Finding similar ingredients…