Related

Filter	Protects against	Notes
Zinc oxide	UVB and the full UVA range, including UVA1	The broadest single filter available anywhere; also a skin protectant monograph active
Titanium dioxide	UVB and short UVA	Better UVB, weaker UVA1; whiter and more opaque

Zinc oxide is the most broadly protective single filter in the world, and it is photostable — it does not degrade under UV the way avobenzone does.

The standard explanation — that mineral filters sit on the skin and reflect UV like tiny mirrors, while chemical filters absorb it — is largely wrong. Measurement shows zinc oxide and titanium dioxide absorb the great majority of the UV that reaches them, with only a modest fraction scattered or reflected. They are semiconductors absorbing photons, not mirrors.

The practical difference from organic filters is not the mechanism. It is photostability, low sensitisation, and the white cast.

Zinc oxide and titanium dioxide are opaque white pigments — the same materials used to make paint white. A mineral sunscreen leaves a visible cast, and on deep skin tones it reads as grey ash.

For decades that was treated as an acceptable trade-off, which in practice meant mineral sunscreen was not a usable option for a large part of the population. The improvements that changed it:

• Micronised and nano-scale particles, which scatter less visible light.
• Iron oxide tints, which both correct the cast and add visible light protection — genuinely useful, since visible light drives pigmentation in melasma.
• Formulation work on dispersion and vehicle.

Tinted mineral sunscreen is now the standard recommendation for melasma and post-inflammatory hyperpigmentation, for exactly that visible-light reason.

The concern is whether nano-scale zinc oxide and titanium dioxide penetrate skin. The weight of evidence is that they do not penetrate intact skin and remain in the stratum corneum; the SCCS has assessed both and permitted them under Annex VI with conditions.

The one exception regulators do treat seriously is inhalation — which is why powder and spray formats using nano titanium dioxide are constrained, and why nano forms are not permitted in applications that could be inhaled.

• Babies and young children over six months — see Baby Sunscreen.
• Sensitive, rosacea-prone or reactive skin. Zinc oxide has an extremely low sensitisation record and is also soothing.
• Post-procedure skin.
• Melasma and pigmentation, where a tinted mineral formula adds visible-light protection.
• Anyone concerned about the filters under FDA review — the twelve organic filters that FDA's proposed order found require further data.

OTC drug in the US: sunscreen monograph, Drug Facts panel, actives listed first, the Broad Spectrum test, tested water resistance at 40 or 80 minutes, and a printed expiration date.

FDA's proposed order under the CARES Act found zinc oxide and titanium dioxide GRASE; PABA and trolamine salicylate not GRASE; and twelve others requiring further data. That proposal is not final.

In the EU, sunscreen is a cosmetic, with filters from the Annex VI closed positive list of 34 entries, including specified nano forms with conditions.

Printed expiration date, typically three years. Mineral filters are inorganic and do not degrade the way avobenzone does — the date reflects the whole formulation.

The practical failure is separation: heavy mineral particles settle, so shake well, and a product that no longer recombines is applying an unpredictable dose of filter.

• Sun and Tanning — the shelf this sits on, and the rest of it.
• Cosmetics — what the label is legally allowed to say, and the full catalogue.
• The rest of Sunscreen — Sunscreen Lotion · Sunscreen Spray · Sunscreen Stick · Chemical Sunscreen · Facial Sunscreen.
• Brightening Treatment — where visible-light protection matters most.
• Regulatory statements here follow the FDA and EU sources listed on Cosmetics, read 16 August 2026.