What Is Benzophenone-5?
Benzophenone-5 is the cosmetic name for benzenesulfonic acid, 5-benzoyl-4-hydroxy-2-methoxy-, monosodium salt. It belongs to the benzophenone family of aromatic compounds that can soak up specific wavelengths of ultraviolet light. The molecule contains a benzophenone core attached to a sulfonic acid group that is neutralized with sodium, which makes it water-soluble and easy to disperse in lotions, gels, and sprays.
Chemists first explored benzophenones in the mid-20th century while looking for additives that could stop plastics and coatings from yellowing in the sun. Their ability to filter UV rays quickly attracted the attention of personal care formulators. Benzophenone-5 gained popularity in the 1970s as brands searched for water-friendly UV filters that would not leave an oily film. Today it is made through a multi-step synthesis that starts with hydroxy-methoxy benzophenone. The compound is sulfonated, then neutralized with sodium hydroxide, and purified into a fine crystalline powder.
Because it dissolves in water, benzophenone-5 is a go-to choice for products where a clear, non-greasy feel is important. You will often see it in daily moisturizers with SPF, facial mists, color-protecting hair sprays, leave-in conditioners, hand creams, and makeup like foundations or tinted lip balms that promise sun defense.
Benzophenone-5’s Cosmetic Benefits/Uses
The ingredient plays several roles that help formulas stay stable and protect the skin or hair from sun damage.
- Light stabilizer – Shields the formula itself so colors, fragrances, and active ingredients do not break down when exposed to light which keeps the product looking and smelling fresh for longer
- UV absorber – Soaks up UV radiation before it can reach the skin or hair reducing the risk of sun-induced dryness or fading
- UV filter – Contributes to the overall sun protection factor in SPF products helping users meet daily photo-protection needs without a heavy texture
Who Can Use Benzophenone-5
Benzophenone-5 is generally suitable for all skin types including oily, combination, normal and even dry skin because it is water-soluble and lightweight. Sensitive or highly reactive skin may need extra caution as any synthetic UV filter has a small chance of causing redness or stinging, but most people tolerate it well.
The ingredient is made through laboratory synthesis using no animal-derived materials so it is considered vegan and vegetarian friendly.
Current research has not flagged Benzophenone-5 as harmful for pregnant or breastfeeding women when used topically in the low concentrations allowed in cosmetics. That said this is not medical advice and anyone who is expecting or nursing should consult a doctor before adding new products to their routine.
Benzophenone-5 does not cause photosensitivity; in fact its job is to absorb UV light and help prevent that issue. It may slightly boost the stability of other UV filters in the formula which can enhance overall sun protection.
Potential Side Effects/Adverse Reactions
Reactions to topical Benzophenone-5 vary from person to person. The following list covers potential side effects that are possible yet unlikely for the average user when the ingredient is formulated correctly.
- Skin irritation – Temporary burning, itching or redness, most often in people with compromised skin barriers
- Contact dermatitis – An allergic eczema-like rash in those who develop sensitivity to the molecule
- Photoallergic reaction – Very rare immune response where the combination of the ingredient and sunlight triggers a rash
- Eye irritation – Stinging or watering if the product accidentally gets into the eyes, especially sprays or mists
- Interaction with fragranced products – In sensitive users the mix of Benzophenone-5 with certain fragrance chemicals might heighten irritation
If any of these effects occur discontinue use immediately and seek advice from a healthcare professional or dermatologist.
Comedogenic Rating
Rating: 0 out of 5
Benzophenone-5 is a small water-soluble molecule that does not linger on the skin or form an occlusive layer, so it is very unlikely to clog pores. Its role is confined to the watery part of a formula and it is used at low concentrations, which further reduces buildup risk. Dermatology references classify it as non-comedogenic.
That makes it a suitable choice for people who are prone to acne or breakouts.
Remember that the overall comedogenicity of a product depends on every ingredient, so check the full ingredient list if pore clogging is a concern.
Summary
Benzophenone-5 serves as a light stabilizer, UV absorber and UV filter by absorbing harmful UV rays and converting them into harmless energy, protecting both skin and the formula itself. Because it dissolves in water it lets formulators create clear lightweight sunscreens, facial mists and hair products without a greasy feel.
While newer next-generation filters are grabbing attention Benzophenone-5 still pops up in a fair number of everyday SPF moisturizers, hair sprays and makeup products thanks to its reliability and cost effectiveness.
Regulatory bodies consider it safe at the approved usage levels and most users experience no issues. As with any new skincare ingredient it is wise to patch test a product containing Benzophenone-5 before full application just to be safe.