But just because tea tree oil is derived from a natural source doesn't mean it works for every skin type. According to Dr. Mahto, it may cause sensitivity and irritation just like other essential oils, so if you're thinking of incorporating it into your skin-care routine, do it as if you were using retinoids or acids for the first time — slowly and with caution. And if your skin reacts, give it a break and seek help from an experienced dermatologist. Say it with us: Just because it's supposedly Meghan Markle's favorite zit-zapper doesn't necessarily mean it'll be yours, too.