Here’s what to know before heading off on your beach vacay.

Before your family’s big beach vacation every summer, your mom might have encouraged you to get a light tan. Pale skin—fresh from your winter hibernation—is more likely to burn, she said, so a light layer of tan will keep you from turning cherry red on the beach. Allegedly.

So … was mom right?

Let’s get right to the point: no, no, no. In this case, mom’s advice was not only wrong, but dangerous, and dermatologists want you to forget this advice ASAP.

The sun emits ultraviolet radiation. Both UVA and UVB rays can penetrate the ozone layer and reach your skin, according to the Skin Cancer Foundation. When those rays hit the inner layer of your skin, skin cells get injured. In response, the skin produces extra melanin—the pigment that gives your skin color.

In other words, a tan = injured skin. That’s an important note since many people believe tans are benign—or even healthy—and only sunburns are a threat to skin health.

Not convinced? Studies have found that using indoor tanning beds (which emit the same UVA and UVB rays) before age 35 increases your risk of melanoma by 59 percent, according to the American Academy of Dermatology. Even a single tanning session can up your risk of melanoma by 20 percent.

So tanning is no harmless pastime. Using tanning (whether out on your patio or inside a tanning bed) to prevent a sunburn is just counterproductive: You’re injuring your skin to prevent injuring your skin. (See the problem?)

And what’s worse, it doesn’t even work. A tan gives you a protection of no more than SPF 3, according to Centers for Disease Control and Prevention. The recommended sunscreen is a minimum of SPF 30, so your SPF 3 “base tan” is giving you about as much protection from the sun as, well, a hope and a prayer.

Instead of relying on the flawed and dangerous base tan, follow skin-protecting strategies on your beach vacay. Apply and reapply sunscreen, wear protective clothing and hats,  and avoid the sun when it’s most intense—between 10 AM and 3 PM.