Mineral sunscreen is the standard recommendation for babies, and the reasoning behind that recommendation is worth actually understanding rather than just following as a rule.
How the Two Sunscreen Types Actually Work
Mineral sunscreens (zinc oxide, titanium dioxide, or both) sit on the skin's surface and physically block and reflect UV radiation. Chemical sunscreens use organic compounds that absorb into the skin and convert UV radiation into heat, which is then released. Both mechanisms can provide effective UV protection at an appropriate SPF — the difference isn't primarily about how well they block UV.
Why Absorption Is the Real Factor for Babies
Because chemical sunscreen filters are designed to be absorbed into skin to work, and infant skin has a higher absorption rate and a less mature skin barrier than adult skin, there's more systemic absorption of the active chemical filters in babies than in adults using the same product. Mineral sunscreen's surface-sitting mechanism means it isn't designed to be absorbed the same way, which is the core reason pediatric guidance leans toward mineral formulas specifically for infants.
Irritation Is the Other Practical Difference
Chemical sunscreen filters are more commonly associated with skin irritation and allergic reactions than mineral formulas, particularly relevant for the more sensitive, reactive skin common in infants. Mineral sunscreen's simpler, physical mechanism carries a lower irritation profile in practice, on top of the absorption consideration.
Verdict
Mineral sunscreen isn't inherently a "stronger" sunscreen than chemical — both can hit comparable SPF protection levels. It's the recommended choice for babies specifically because of lower systemic absorption and lower irritation risk on infant skin, which is why pediatric guidance treats it as the default under 6 months, with sun avoidance and protective clothing as the first line of defense either way.
