Britney Spears has opened up about a botched Botox procedure that left her eyelid drooping, warning fans to “be careful” with cosmetic treatments.

The musician, 44, described the unwanted after effects of the injections in an Instagram video, which she captioned “You can’t trust anyone!!!”

Spears claimed that her injector “put so much Botox in this left eye that it drooped down like that”, before demonstrating its impact by pressing her eyelid down with her finger.

The “Baby One More Time” singer said that four weeks on from the procedure, her eyelid is “just now starting to raise up and be normal again”.

“It's so embarrassing it was like that,” she continued, before cautioning her fans to “be careful if you do Botox”.

“These people and these doctors, they can really f*** your eyes up,” she claimed.

“Be careful with these people,” Spears added. “They try to change your face and try to f*** things up. Be careful with your bodies, because it’s yours and you own it. So, that’s it.”

Earlier this week, the star made the emotional admission that she felt as if she had “failed” as a parent to her sons Sean Preston, 20, and Jayden James, 19, who she shares with ex-husband Kevin Federline, after one of her children told her that he does not believe in God and instead believes in science.

“In that moment I believed I had failed as a mother,” she wrote in a post shared on Twitter, before adding: “I wanna tell my kids and people in general that I’m sorry for my mistakes in the past.”

Last month, Spears spoke out after fans shared their concerns over photos that appeared to show her standing through an open sunroof of a car in traffic.

She told her followers that “nothing is what it seems” and that the photos captured “two seconds of insanity” out of “the days and hours of my reality”.