JLo shared a video of her face on Instagram after using a mask from her new beauty range.
Speaking in the clip while examining her complexion, the star said: "Honestly, I cannot even see a line on my face, it is glowing and gorgeous and tight and yummy."
The singer said she thinks the mask "took 10 years off my face".
Some of Lopez's fans accused her of being disingenuous, claiming that the 51-year-old's youthful skin couldn't be attributed to the face mask.
One commenter said: "Ma'am! Please stop acting like that isn't just genetics and moolah!!!!"
Another wrote: "Love her. But let’s be real. That mask isn’t what gives her that skin. It’s lasers and her dermatologist and other treatments combined with her skincare. You can use this mask for the rest of your life and not have skin like that. This mask is like a chef giving you half the recipe to his secret sauce."
One follower commented: "But 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."
To this message, JLo responded: "LOL that's just my face!!! ....For the 500 millionth time... I have never done Botox or any injectables or surgery!! Just sayin'".
She added: "Here is another JLO Beauty secret: try spending your time being more positive , kind and uplifting of others don't spend your time trying to bring others down that will keep you youthful and beautiful too!!!"
The star's skincare range, JLo Beauty, launched on New Year's Day, after three years in the works.
Last year, the singer revealed how she got her iconic nickname, Jlo, while appearing as a judge on World of Dance, explaining that the name came from the late rapper Heavy D.
During an advert break on the show, she said: "JLo came from Heavy D."
"Remember Heavy D? The rapper. He would come into the studio when I was making my first album, and he would always call me Jenny Lo," Lopez said, according to a clip shared by Access. "And I was dating Puffy at the time, and so, Puffy and Jennifer Lo, or Jenny Lo, was showing up in records. Like, they were talking about us in records and stuff like that.
"So I was like, I’m going to name the album 'JLo.'"