Period blood masks are one of the latest beauty trends in skincare. Proponents of this treatment claim menstrual blood nourishes skin, clears acne and offers a host of other benefits. But in reality, there is no evidence to support this, and moisturizing with period blood could instead lead to a number of skincare problems, including infection.

We talked with an OB-GYN and a skincare specialist to learn more about this fad. Here's what they want you to know before you start saving the contents of your next menstrual cup for an at-home facial.

What exactly is a period blood mask?

A menstrual blood mask is precisely what it sounds like: using period blood on your face for a mask. Typically, a menstrual cup is used to collect the blood, which is either immediately applied to the face or stored in a jar in the refrigerator for later use. The blood is then smeared on the face and left to dry, much like a mud mask, though the consistency is thinner because period blood is more watery.

What's actually in period blood?

Kecia Gaither, M.D., M.P.H., double board-certified