Kylie Jenner first set tongues wagging when her lips started to look more plump during red carpet appearances in 2014.
Although she was only in her mid-teens at the time, rumours whirled over whether the reality star had sought cosmetic help to boost her pout.
Now, aged 18, she admits to using fillers and even told Allure magazine: "I definitely made my lips a little too big at one point... I got excited and felt like I needed to do a lot.
"And then you guys were like, 'Kylie, you need to chill.' And then I had to go back and have it fixed, and it was a crazy process. Thank God I didn't end up on Botched."
But according to a UK plastic surgeon, anyone looking to enhance their lips should wait until 25 before turning to the needle.
Mr Thangasamy Sankar, a consultant plastic surgeon from Ramsay Healthcare UK, said: "We've had girls as young as 15 approach us wanting breast surgery which we just wouldn't do.
"Bodies need to stop growing before you start changing them. We've also had very mature people in their 90s coming to us for face lifts or eye lid reductions.
"These are best performed when patients have enough elasticity left in the skin to bounce back. Although saying that, there is no upper age limit but surgical procedures are invasive and they do carry risks which need to need to be taken into consideration, particularly in older patients."
He advises teenage girls to wait until they are in their mid-20s before seeking cosmetic help. "For lip enhancement, dermal filler can be used at any age but is most commonly used from 45 and over to soften the fine lines that can develop at the edge of the lip," he advises.
"It also enhances the volume of the lip and lip definition. You can have temporary lip augmentation using temporary or permanent filler materials.'"
Here the surgeon shares an infographic that reveals the best ages to have the other most common procedures done - and they might surprise you.
While breast surgery, liposuction and nose jobs can be done when a person is 18 or over, he recommends waiting for other procedures.
In the infographic he says that women over 18 who want to boost their breasts can have implants, for those seeking the surgery after the age of 30, they'll be correcting a loss of volume after pregnancy.
He also says that over 18 is the time for a breast reduction.
The tail end of your teens is the time for a nose job, or rhinoplasty, for those who want one according to the surgeon.
He also says that over 18 is the time that people considering liposuction should be considered. He added, "liposuction is used more and more for reshaping rather than reducing weight and bulk. The procedure must be part of a lifestyle change combined with exercise and a healthy diet."
He says that the only cases of people who are 18 that should have injectables done is to cure migraines or excessive sweating.
According to Mr Sankar, you should wait until you're 45 or older to have eyelid and eye bag reductions, facelifts and injectables such as Botox.
The surgeon also notes that aesthetic surgery is becoming more popular in men as they seek to reduce puffiness through surgery.