The Science of Avobenzone in Sunscreens

Avobenzone, also known as butyl methoxydibenzoylmethane, is the main UVA filter in most oxybenzone-free chemical sunscreens sold in the United States. It was developed to offer protection from the longer UVA1 wavelengths tied to photoaging and pigmentation. However, because avobenzone has a chemistry quirk that causes a loss of photostability in sunlight, it is typically combined with other SPF ingredients.

Avobenzone is a synthetic, oil-soluble compound belonging to the dibenzoylmethane class of organic UV filters. Unlike mineral filters such as zinc oxide, which sit on the skin's surface and reflect UV radiation, avobenzone works by absorbing ultraviolet energy and releasing it as heat. It covers both UVA1 (340 to 400 nm) and UVA2 (320 to 340 nm) wavelengths, with peak absorption around 357 to 360 nm, giving it one of the broadest UVA absorption ranges of any FDA-approved sunscreen active.

Because avobenzone is oil-soluble, it is often included in water-resistant lotions, sprays, and sticks. It has been part of the US sunscreen market since the late 1980s and remains one of the few ingredients capable of covering the far end of the UVA spectrum on its own.

Avobenzone is a single molecule, but its behavior in a sunscreen depends on two forms that it shifts between when exposed to UV light.

• Enol tautomer – the stable, UV-absorbing form of avobenzone as it sits in a fresh formulation, responsible for its broad-spectrum UVA protection.

• Diketo (keto) tautomer – an unstable form the molecule converts to after absorbing UV energy. This form does not effectively absorb UV light and is the reason avobenzone loses potency with sun exposure unless a stabilizer intervenes (3).

• p-Anisic acid – one of the byproducts formed as avobenzone degrades under UV light. Some newer formulations use it deliberately as part of a stabilizing antioxidant system.

• Broad UVA1 coverage – avobenzone absorbs across the full UVA1 range, which is important because UVA1 penetrates deeper into the skin and is strongly linked to collagen breakdown and hyperpigmentation.

• Improved photostability with the right pairing – pairing avobenzone with octocrylene helps to stabilize it. Octocrylene absorbs the excess energy from avobenzone's unstable form before it can break down, so this combination degrades in sunlight much more slowly than avobenzone does on its own (3).

• Works well in water-resistant formulas – its oil solubility makes this ingredient easy to incorporate into water-resistant sunscreen bases, useful for anyone who sweats, swims, or spends long stretches outdoors.

• Noncomedogenic – Avobenzone is generally considered noncomedogenic and is commonly used in sunscreens formulated for acne-prone skin.

The Environmental Working Group (EWG) rates avobenzone with a hazard score of 2 out of 10 and "fair" data availability. Its main flagged concerns are enhanced skin absorption and moderate use restrictions, alongside low-level concerns for endocrine disruption and skin or eye irritation. EWG's contamination concerns for avobenzone relate to trace breakdown compounds, such as benzaldehyde and benzoic acid, rather than the parent molecule itself.

Because avobenzone functions as an active drug ingredient in over-the-counter sunscreens, it is typically reviewed under the FDA's sunscreen monograph process rather than assessed independently by the Cosmetic Ingredient Review (CIR), which generally defers on active drug ingredients already under FDA review. A separate, industry-funded toxicology review published in 2025 concluded that avobenzone has a suitable safety profile without clear markers of toxicity (4).

Contact allergy to avobenzone itself is uncommon. Most reactions attributed to it are actually photoallergic responses to compounds formed when avobenzone breaks down in sunlight, particularly a group of degradation products called arylglyoxals, which were shown to be strong sensitizers in laboratory testing (5). Avobenzone can also cause stinging if it migrates into the eyes, and formulations containing it are generally a poor fit for people with rosacea or stinging-prone, sensitive skin.

If you have rosacea or other sensitive skin subtypes, sunscreens with avobenzone are not likely to be the best fit for you. Instead, choose a gentle sunscreen like these options below to reduce stinging and redness.

Avobenzone offers some of the best UVA protection out of a chemical sunscreen ingredients, and when it's properly stabilized, it holds up well through a normal day of sun exposure. While it can be a reasonable choice for most skin types, avobenzone isn't the best fit for people who are prone to stinging, rosacea flares, or photoallergic reactions – mineral SPFs are a better alternative if you fit into this group.

Not sure which sunscreen ingredients suit your skin best? Take the Baumann Skin Type Quiz to find out.

1. Baumann L. and Weisberg, E. Sunscreens in Ch. 46 of Baumann's Cosmetic Dermatology Ed 3. (McGraw Hill 2022)
2. Baumann, L. Ch. Cosmeceuticals and cosmetic Ingredients (McGraw Hill 2015)
3. Kikuchi A, Oguchi-Fujiyama N, Miyazawa K, Yagi M. Triplet–Triplet Energy Transfer from a UV-A Absorber Butylmethoxydibenzoylmethane to UV-B Absorbers. Photochemistry and Photobiology. 2014;90(3):511-516. DOI: 10.1111/php.12222.
4. Norman KG, Kaufman LE, D'Ruiz C, et al. Comprehensive review of avobenzone (butyl methoxydibenzoylmethane) toxicology data and human exposure assessment for personal care products. Critical Reviews in Toxicology. 2025;55(6):662-692. DOI: 10.1080/10408444.2025.2535394.
5. Karlsson I, Hillerström L, Stenfeldt AL, Mårtensson J, Börje A. Photodegradation of dibenzoylmethanes: potential cause of photocontact allergy to sunscreens. Chemical Research in Toxicology. 2009;22(11):1881-1892. DOI: 10.1021/tx900284e.