Sunscreen
Also known as SPF, UV filters, photoprotection
The single highest-return item in any looks routine. Everything else is damage repair; this is damage prevention.
$10–40 per bottle; a daily-use face sunscreen lasts roughly 2 months.
How it works
UV filters absorb or scatter ultraviolet radiation before it reaches the dermis. UVB drives sunburn and direct DNA damage; UVA penetrates deeper and drives collagen breakdown and pigmentation — which is why broad-spectrum coverage matters more than the SPF number alone.
How it's used
Broad-spectrum SPF 30 or higher, every morning, indoors or out. Roughly a quarter teaspoon for the face — almost everyone under-applies by half. Reapply every two hours with meaningful sun exposure. Modern Asian and European filters are cosmetically far more elegant than older US formulations.
Trade-offs
In favour
- The best-evidenced anti-ageing intervention that exists
- Prevents photoaging, pigmentation and skin cancer
- Protects the results of every other treatment you pay for
- Cheap relative to correcting the damage
Against
- Must be applied daily and correctly to work
- White cast on deeper skin tones with some mineral filters
- Can feel heavy or trigger breakouts if poorly formulated
- Regulatory lag means the best filters are unavailable in some markets
Risks and side effects
- Contact irritation or allergy to specific filters
- Under-application gives far less protection than the label suggests
How good is the evidence?
Randomised trial evidence demonstrates measurable reduction in photoaging with daily use, alongside strong skin cancer prevention data.
Sources
- Sunscreen and photoaging prevention trial evidencePubMed
- Sunscreen guidanceAmerican Academy of Dermatology
Sources point to guideline bodies and literature searches rather than single papers, so they stay accurate as the evidence moves.