The singer/actress, 51, clapped back at a user who said she must "definitely have Botox" after JLo posted a video of herself using a face mask from her new beauty line, JLO Beauty.
"I feel like it took 10 years off my face," Lopez said in the clip of the mask.
One Instagram user wrote, "Can I just mention that brows and forehead doesn't move at all when you talk or try to express... you definitely have Botox. And tons of it. And it's all good. Just saying."
Lopez replied, "LOL that's just my face!!!"
"For the 500 millionth time... I have never done Botox or any injectables or surgery!! Just saying. Get you some JLO Beauty and feel beautiful in your own skin!!" she added.
"Try spending your time being more positive, kind and uplifting of others," Lopez added. "Don't spend your time trying to bring others down that will keep you youthful and beautiful too!!! Sending you love. #beautyfromtheinsideout #beautyhasnoexpirationdate."
On choosing to opt-out of Botox, Lopez explained, according to Page Six: "I'm not that person. I don’t have anything against people doing that; it’s just not my thing. I’m more about a natural approach to skincare … but I want [my products] to work. I want the hyaluronic acid in there. I want the things that are going to help, because I don’t want to have to go to the needles at some point."
One of her biggest beauty tips is relatively simple, as well.
"One of the big things I would encourage everybody to do from the time they’re 15 years old, even younger, is wear sunscreen every day," said Lopez. "That’s a big skincare secret that people kind of do but don’t do. They use moisturizers, but they don’t put on sunscreen every day. That is something I have done from that time I was 22 years old."
Fox News' Nate Day contributed to this report.