Do not buy sunscreen in bulk or store it from season to season.

When used correctly, it is easy to go through sunscreen quickly, and sunscreens can be expensive. Therefore, it can be tempting to buy sunscreen in bulk to save money, or to "stock up" on sunblock that is on sale at the end of the season. Resist this temptation: as sunscreen ages, its effectiveness can weaken. Generally, sunscreens have shelf life of approximately two years, and you cannot be sure how long sun screen has been on the store´s shelf. So unless you are planning to use sunscreen for a large group (such as a club), buy only enough to get you through a month or two, and play it safe at the start of a season and discard lotions leftover from the previous year. It might seem expensive, but the long-term benefits of effective protection will make it worth your money.