Sunscreen filters: mineral or chemical? A guide to reading the label

Types of filter: mineral and organic

The UV filters in sunscreens fall into two main groups. Mineral (inorganic) filters are zinc oxide and titanium dioxide. They work mainly by absorbing UV rays and partly by reflecting and scattering them. Organic filters (popularly called “chemical filters”) are carbon-based molecules that absorb UV radiation and convert it into heat.

The word “chemical” is misleading: zinc oxide is a chemical too. That is why we use the term “organic filter” in this article. It is worth remembering that both groups provide effective protection when well formulated. Many modern sunscreens combine the two groups for broad-spectrum protection.

Mineral filters: zinc oxide and titanium dioxide

• Zinc oxide: Provides broad protection against both UVB and UVA rays. Its absorption through the skin is very low and its potential for irritation is small; this is why it is often chosen for sensitive skin and children's products.
• Titanium dioxide: Very effective against UVB, slightly more limited than zinc oxide in UVA protection. It is of low concern on the skin.

The best-known drawback of mineral filters is that they can leave a white cast on the skin. To reduce this, the particles are made smaller; this is why you see “(nano)” on the label. In the EU, nanomaterials must be indicated on the label, and the nano forms used as filters have been assessed by the SCCS. On intact skin, nanoparticles are not considered to pass into the deeper layers of the skin.

The main point of caution with titanium dioxide is inhalation. In the EU, nano titanium dioxide may not be used in applications that could lead to exposure of the lungs through inhalation. In food (E171), a separate assessment was carried out, and it was withdrawn from use in the EU in 2022 and in Türkiye in 2024; for this reason our app rates it high in the food category and in a wide range in cosmetics, depending on the type of product.

Organic filters: which ones are debated?

• Oxybenzone (Benzophenone-3): One of the most debated filters, because it can be absorbed through the skin and may show weak hormone-like effects. Following the SCCS assessment, the maximum permitted level in the EU was lowered from 10% to 6% in face, hand and lip products and to 2.2% in body products, including sprays; a “Contains Benzophenone-3” warning on the label became mandatory. It can also cause photoallergic reactions in some people. For these reasons our app rates it in a moderate-to-high range.
• Homosalate: Following the SCCS assessment, its permitted concentration in the EU was lowered from 10% to 7.34% and its use restricted to face products, excluding propellant (aerosol) sprays; this rule has applied since 2025.
• Octocrylene: A UVB filter often used to stabilise other filters, such as avobenzone, against light. It can cause allergic or photoallergic reactions in some people. Findings suggesting that benzophenone may form in the product over time are being debated; following the SCCS assessment, the EU updated its conditions of use: the maximum is 10% in general and 9% in propellant spray products.
• Avobenzone (Butyl Methoxydibenzoylmethane): One of the most common UVA filters. Because on its own it can break down in sunlight, it is usually combined with stabilising filters. Its level of concern is considered low to moderate.

There are other modern filters approved in Europe (for example, filters seen on labels under long names such as Bis-Ethylhexyloxyphenol Methoxyphenyl Triazine or Methylene Bis-Benzotriazolyl Tetramethylbutylphenol). These are generally more stable in light, and their absorption through the skin is limited.

What to watch out for with spray sunscreens

Spray products are practical and make it especially easy to cover large and hairy areas. However, they have two important drawbacks:

• Not enough product: With sprays it is hard to judge how much product actually reaches the skin, and in the wind some of it disperses into the air. Spraying generously onto the skin and then spreading it by hand helps create an even and sufficient layer.
• Risk of inhalation: Sprays should not be sprayed directly onto the face. For the face, it is better to spray the product into your palm first and then apply it. When using sprays on children, make sure they don't breathe the product in.
• Alcohol content: Many sprays contain alcohol (Alcohol Denat.) so that they dry quickly; this can dry out dry and sensitive skin. They are also flammable, so they should not be applied near a flame.

More important than the filter: correct use

SPF is measured in the laboratory by applying 2 mg of product per square centimetre. In everyday life most people use much less than this, which means the real protection is lower than the label says. For the face and neck you need about two finger-lengths of cream, and for the body several tablespoons of product.

Sunscreen wears off with sweating, towelling and swimming. If you are outdoors for a long time, it is recommended to reapply about every two hours and after every swim or heavy sweating. “Water-resistant” shows that the product keeps its effectiveness in water for a certain time, but it does not remove the need to reapply.

On the label, “broad spectrum” or the EU UVA logo (the letters UVA in a circle) shows that the product also meets a certain standard for UVA protection. The SPF value only describes UVB protection.

Which filter for whom?

• Sensitive skin, skin prone to redness or rosacea: Mineral-filter and fragrance-free products are generally better tolerated.
• Darker skin tones: The white cast of mineral filters can be bothersome; tinted mineral formulas or well-tolerated organic-filter products may be preferable.
• Children: Mineral-filter, fragrance-free products made for children are often chosen. For babies under six months, follow your paediatrician's advice on sun protection. For details, see our baby and children's products guide.
• Sport and the beach: Choose water-resistant products that are easy to reapply.

Sunscreen should be used alongside measures such as shade, a hat, sunglasses and avoiding the midday sun, not instead of them. If you notice a new or changing mole on your skin, it is important to see a dermatologist.