Is it true that … starting Botox in your 20s will stop you getting wrinkles?

Yes, says Dr Afshin Mosahebi, a professor in plastic surgery at University College London: injecting botulinum toxin (commonly known as Botox) into areas of the face before fine lines start forming can slow their development – but that doesn’t mean you should.

“Facial wrinkles happen for two reasons,” he says. One is that when our muscles move, the skin over them is repeatedly scrunched and – in the same way that constantly scrunching up a piece of fabric will ultimately leave a crease – it begins to etch lines into the skin. The other reason is the thinning of the dermis layer of the skin, which happens “as we get older, and particularly as we are exposed to the sun”, Mosahebi says. The thinner it is, the more susceptible it is to wrinkles.

Botox injections tackle the first cause of ageing, paralysing muscles in the face for about six months at a time. With wrinkled skin, this makes lines less visible. On unwrinkled skin, research shows that regular use makes it harder for wrinkles to form. But it’s not a panacea, Mosahebi says. Thinning of the skin will still lead to lines developing, just to a lesser extent, and if you stop the injections you’ll age as normal. Plus, the longer you use botulinum for, the more you have to use to get the same effect.

“Over time, you become more resistant to toxins, so an amount of botulinum that would work at the beginning of your treatment might not work so well later on,” Mosahebi says. More than that, he thinks starting too early “encourages people to get completely fixated on how they look, which we want to avoid”.

He would encourage a twentysomething to take measures to slow the skin-thinning process – such as staying out of the sun and avoiding smoking – before considering injections. In your 20s, he says, “sun cream is a much better option than Botox”.