You know sunscreen is a must to help protect your skin outdoors. But if you’re not careful, doctors say you can get burned by the product designed to protect you.

One common mistake is that people can have a false sense of security by assuming a sunscreen is waterproof.

No brand is water “proof.”

In fact, the Food and Drug Administration no longer allows products to make those claims.

Another issue is with spray-on sunscreens - especially those that contain titanium dioxide, which can be highly toxic if inhaled.

"If you’re going to do the face, I often recommend spray into your hand first. Then take a little bit with your fingertips and then evenly apply to the face or to the scalp so you avoid any incidental inhalation," says Dr. Shannon Trotter, a dermatologist at the Ohio State University Wexner Medical Center.

She says another way you can get burned by your sunscreen is by paying more for higher SPF ratings.

She says an SPF of 30 will block 97 percent of harmful rays and anything over 30 does not offer significantly more protection.

Also, when buying sunscreen, look for products that say “broad spectrum” on the label.

Those protect from both UV-A and UV-B sun rays, the two types that pose the greatest risk for skin cancer.

Dr. Trotter says just five bad sunburns can double your lifetime risk of melanoma, the deadliest form of skin cancer.