Chemical and physical sunscreens: differences and which one to choose

When choosing sun protection, even before considering the SPF, there is a question that causes confusion: are chemical filters or physical filters better? There are simplifications and outright myths surrounding this topic — starting with the idea that mineral filters "reflect" rays like a mirror. In this entry of our glossary, we clarify: let's see how the two families of filters really work, their pros and cons, and how to choose based on your skin type.

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What are sun filters

Sun filters (or UV filters) are the ingredients that make a sunscreen capable of protecting the skin from ultraviolet radiation: UVB, responsible for sunburns and direct damage to cellular DNA, and UVA, which penetrate deeper and are the main cause of photoaging and spots. In Europe, the filters allowed in cosmetics are listed in Annex VI of Regulation (EC) 1223/2009: only molecules assessed as safe by the Scientific Committee on Consumer Safety (SCCS), within defined maximum concentrations, can be included in formulas.

The two main families are organic filters, commonly called "chemical," and inorganic filters, called "physical" or "mineral." The distinction in names is more commercial than scientific — mineral filters are, in fact, chemical substances — but this is now the language everyone knows them by.

Chemical filters (organic): how they work

Chemical filters are organic molecules that absorb UV radiation: they capture the photon's energy and transform it into a very small amount of heat, releasing it harmlessly. Among the most used in Europe are INCI names like Ethylhexyl Triazone, Bis-Ethylhexyloxyphenol Methoxyphenyl Triazine (known as Tinosorb S), Methylene Bis-Benzotriazolyl Tetramethylbutylphenol (Tinosorb M, which also has partly physical behavior), and Diethylamino Hydroxybenzoyl Hexyl Benzoate.

Their strengths are concrete:

• Light and transparent textures: they spread easily, do not leave a white residue, and suit fluid formulas, ideal for daily use on the face.
• Broad-spectrum protection: new generation filters cover UVA and UVB very efficiently and photostably.
• High protection with low dosages, which improves the formula's pleasantness.

The historical limitation of chemical filters is tolerability: some older molecules (like Oxybenzone, now increasingly less used) could cause sensitization on reactive skin. Modern filters are much more stable and better tolerated, but caution is still necessary on compromised skin or with ongoing dermatitis.

Physical filters (minerals): how they really work

There are two physical filters: Titanium Dioxide and Zinc Oxide. They are mineral powders that remain on the skin's surface and protect mainly... by also absorbing UV radiation.

The advantages of mineral filters:

• Excellent tolerability: being inert and not penetrating healthy skin, they are the first choice for sensitive, reactive skin, for children, and after dermatological treatments.
• Photostability: they do not degrade with sun exposure.
• Immediate effectiveness after application.

The disadvantages are mainly cosmetic: the white effect (reduced but not eliminated by micronized forms), denser textures, and some difficulty reaching very high SPF without weighing down the formula. To limit the white cast, the industry uses nanoparticle forms, indicated in the INCI by the term nano in square brackets immediately after the ingredient name: on intact skin, they remain on the surface and are considered safe by the SCCS under approved usage conditions, while inhalation is discouraged (so be careful with mineral-based spray formats).

Chemical or physical: the differences in summary

Placed side by side, the two families differ as follows:

1. Mechanism: both absorb UV radiation; minerals also scatter a small portion. The real difference is not "absorb versus reflect," but the nature of the molecules.
2. Texture: chemical formulas are lighter and invisible, mineral ones are thicker and tend to white.
3. Tolerability: highest for minerals; very good for new generation chemical filters, with some extra caution on reactive or damaged skin.
4. Protection breadth: the best results today are often achieved by combining multiple filters, even from both families together, to cover the full UVA and UVB spectrum photostably.

Which to choose based on skin type

There is no absolute winner: there is the right filter for the right skin. Some practical guidance:

• Sensitive, reactive skin, with couperose or dermatitis: favor mineral filters or formulas with new generation chemical filters tested for sensitive skin, and look for soothing actives like thermal water and ceramides in the formula.
• Oily or acne-prone skin: the priority is a light, non-comedogenic, sebum-absorbing texture; modern chemical filters in fluid or gel vehicles are generally the most comfortable choice.
• Skin with spots or discolorations: an SPF 50 broad spectrum is needed all year round, preferably with antioxidants (like Vitamin C) that also counteract UV-induced oxidative stress.
• Children and damaged skin: mineral filters in cream form, avoiding sprays.

For those seeking daily anti-spot protection, our facial sunscreen combines broad-spectrum UV filters, encapsulated Vitamin C, and probiotic ferments in a light texture suitable even under makeup.

And to solve everyone's real problem — reapplication every two hours — there is the pocket-sized format, smaller than a credit card, to always keep in your bag or wallet.

After-sun and reactivity: the rest of the team

Protection is only half the summer job: after exposure, the skin needs to be rehydrated and soothed. A thermal water spray rich in minerals helps calm redness and strengthen the skin barrier after a day in the sun.

For more information, also read our guide to choosing the best sunscreen for every skin, tips on what to put on sensitive skin after sun exposure, and the in-depth article on the relationship between sunscreen and vitamin D.

In summary

Chemical and physical filters achieve the same goal by slightly different means: the former absorb UV with organic molecules in light, invisible textures, the latter with inert minerals offering impeccable tolerability. Modern formulas often combine them to get the best of both. More than the filter family, three things matter: broad UVA/UVB spectrum, correct quantity, and consistency in reapplication. The perfect sunscreen, in the end, is the one you really use every day.