Avobenzone

Avobenzone is a chemical, or organic, sunscreen filter that works by absorbing UV radiation and converting it into a small amount of heat, rather than reflecting it away from skin. It is one of the few filters approved in the United States that covers the entire UVA spectrum on its own, which makes it a common backbone ingredient in broad spectrum formulas.

Its major limitation is photoinstability, meaning avobenzone's molecular structure breaks down noticeably within roughly an hour of sun exposure unless it is paired with a stabilizing ingredient. Research testing antioxidants as potential stabilizers found several compounds meaningfully slowed avobenzone's rate of photodegradation, supporting the formulation strategies brands use to keep it effective throughout a day of wear. A separate toxicology review assessing avobenzone's human exposure and safety data found its current use levels in personal care products fall within an acceptable safety margin, supporting its continued approval as a broad spectrum UVA filter when properly stabilized.