3 Things to Know About the Two-Hour Sunscreen Rule

Reapply sunscreen every two hours without exception The two-hour rule exists because sunscreen breaks down from sweat, water, towel drying, and UV exposure itself, not just from washing off.

Water-resistant labels do not mean all-day protection Water-resistant sunscreen only holds up for 40 or 80 minutes while swimming or sweating, not for the entire day.

Reapply immediately after swimming or toweling off Set a phone alarm to remind yourself, and do not trust cloudy skies — UV rays still penetrate through clouds.