Titanium Dioxide.

What it does

It is one of the gentlest sunscreen options, which is why it is a mainstay of products for sensitive and reactive skin, and is often paired with zinc oxide for fuller UVA coverage.

Benefits

• Broad-spectrum sun protection, strongest against UVB and UVA II
• Very gentle and non-irritating, ideal for sensitive or reactive skin
• A staple in mineral and baby/sensitive-skin sunscreens
• Works immediately and pairs well with zinc oxide for full UVA coverage

Side effects

• Can leave a white cast, especially non-nano grades on deeper skin tones
• May feel thick or hard to spread compared with chemical filters

Who it's for

Sensitive, reactive, or easily irritated skin needing daily sun protection

Who should be careful

Best avoided in loose-powder or spray forms where the fine particles could be inhaled; topical use on intact skin is considered safe

• Titanium dioxide - Wikipedia