How Often Do You Need To Reapply Sunscreen?

Picture yourself with sunglasses and a headscarf on, driving an old Thunderbird convertible with your bestie in the passenger seat, Thelma and Louise style.

Yes, Susan Sarandon had the most killer tan in that movie, and not a single scene featured those desert-driving babes applying sunscreen. This is real life, however, where sun damage exists. We're here to tell you that you better slap on some sunscreen before you take that joy ride.

The Skin Cancer Foundation (SCF) says that daily application of Sun Protection Factor (SPF) 15 year-round can reduce your chances of squamous cell carcinoma by 40%, and lower the risk of melanoma by up to 50%. As if that isn't reason enough to lather up, the Cleveland Clinic points out that repeated sun damage can cause premature aging, wrinkles, sunspots, and leathery-looking skin.

We know you're not down for all that, so we're here to outline the best sunscreen practices for you.

A sunburn may be a one-off reaction from a long, hot day at the beach, but sun damage occurs beneath the skin over the span of a lifetime. For that reason, the SCF advises that everyone — no matter their skin tone or whether or not they burn easily — should be wearing sunscreen every day. According to the Cleveland Clinic, SPF 15 should do the trick for daily wear, but if you're spending the day out in the sun, SPF 30 or higher is necessary.

Whether you're wearing SPF 15 or SPF 90, you should be reapplying sunscreen throughout the day. Dr. Joshua Zeichner, the director of cosmetic and clinical research in dermatology at Mount Sinai Hospital, told Healthline that reapplication is necessary every 2 hours, "or immediately after heavy sweating or swimming." That's because ultraviolet (UV) rays interact with sunscreen, making it less effective over time. In addition, sweating off sunscreen on a hot day is all too common.

When buying sunscreen, something to look for in addition to the SPF is a label that reads "broad spectrum." This simply means it is effective in blocking both UVA and UVB rays. The Cleveland Clinic recommends that you apply whatever sunscreen you choose to your whole body (including your ears, your hairline, and the backs of your hands, knees, and neck) 30 minutes before sun exposure. Lather up before getting dressed so that every bit of you is protected, even if your clothes happen to move throughout the day.

Now that you've got your sunscreen and know how often you need to put it on, we should probably be clear on how much sunscreen you should be applying. The SCF says that 1 ounce (or a shot glass-sized amount) should be applied per whole body with every application. Don't think about skimping, either — less cream equates to less protection. Now put that top down and cruise!