The very thought of plucking your brows too thin may elicit a shudder—that’s because when you tweeze, and tweeze, and tweeze, you can actually damage the follicle. Once that happens, the hair will never be able to grow back, no matter how many serums you paint on. (Read: When a follicle dies, no ingredient will bring it back to life.)

“Plucking, tweezing, threading, and waxing all pull the hair from the root, and there’s only so much trauma each root can take,” board-certified dermatologist Whitney Bowe, M.D., has previously told mbg about brow growth. “Repeating these insults to our hair root over time increases the likelihood that some hairs will never regrow, as too much damage has been done to the base of the root where the stem cells live.” Use those tweezers for good—a stray hair here and there—and remain gentle on those delicate wisps. 

https://www.mindbodygreen.com/articles/common-brow-mistakes-and-how-to-remedy-them-from-experts