Jennifer Lopez responds to doubters: I have 'never' used Botox

After posting an Instagram video promoting her new skin care line, actress and music star Jennifer Lopez is responding to speculation that she has had Botox injections or other surgery to achieve highly youthful skin for a 51-year-old woman.

In an evidently makeup-free video Lopez posted Friday extolling the virtues of her That Limitless Glow skin care mask, she marvels, "Honestly, I cannot even see a line on my face. It is glowy and gorgeous and tight and yummy and, like, ohmigod, this is the best mask that I've ever, ever tried. … Talk about the JLo glow! Wow. I think we're ready for the market. We've got to charge $10,000 apiece for these!" she jokes.

In a comment either no longer on the page or buried amid countless others, one person wrote, according to a People magazine screengrab, "But can I just mention that [your] brows and forehead doesn't [sic] 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."

"LOL thats [sic] just my face!!!" former Old Brookville resident Lopez responded. "For the 500 millionth time … I have never done Botox or any injectables or surgery! Just sayin'."

She added, "And 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!!! Sending you love. #beautyfromtheinsideout #beautyhasnoexpirationdate."

Many other commenters also suggested that Lopez has had injections of Botox, a trademarked brand of onobotulinumtoxinA used to reduce the appearance of facial wrinkles by temporarily preventing a muscle from moving.

Other comments suggested genetics and self-care were at work. "Woman of color age different[ly]. My grandma is almost 90 and has no wrinkles," wrote one. Another noted that Lopez "doesn't drink or smoke, has a strict diet, and has worked out her entire life. It absolutely affects the skin."

Medical professionals say nonprescription skin care products such as JLo Beauty's mask, which comes in a three-pack for $48, are not regulated by the Food and Drug Administration and have no guaranteed efficacy.

Like many such products, her mask includes such ingredients as niacinamide, which "helps reduce water loss in the skin and may improve skin elasticity," according to the Mayo Clinic, and tetrapeptide-14, one of a class of compounds, peptides, "able to stimulate collagen production, and … improve skin texture and wrinkling." But as the clinic notes of any such products, you may need to apply them "once or twice a day for many weeks before noticing any improvement. And once you discontinue using the product, your skin is likely to return to its original appearance."