The hot, hazy days of summer are here and it’s time to stock up on sunscreen, but now there are other options on the shelf. Moisturizers, makeup, and lip balms come with a sun protection factor (SPF) rating, but can those products offer true protection from the sun’s harmful UV rays?

According to Consumer Reports, makeup with SPF is never a substitute for sunscreen because most users don’t use enough to truly protect their skin.

“You should be using one whole teaspoon of sunscreen for your face and neck. That’s a lot,” said Consumer Reports Health Editor Trisha Calvo. “It would be hard to use the same amount of foundation with SPF to get effective coverage without looking like you’ve applied a makeup mask and you're not likely to reapply every two hours”

According to a new study published in the scientific journal PLOS One, participants who put on moisturizers with SPF were likely to miss areas around the eyes, a common site for skin cancer.

Most dermatologists recommend people use sunscreen with SPF 30, but most beauty products only contain SPF 15. Researchers recommend that users first apply sunscreen to their body before putting makeup on.

“Work it carefully around your face,” said Calvo. “Make sure to wear sunglasses with a label of 99 to 100 percent UVA and UVB protection.”

Calvo also said that sunscreen needs to be reapplied at least every two hours to be truly effective.

There is no benefit to layering up SPF products—using a moisturizer with SPF 15 and foundation with SPF 15 won’t increase the user’s protection to SPF 30.