Kendall Jenner's looks have earned her millions as a catwalk model, but she reveals her self-confidence took a huge hit during her teenage years.

The model, rarely seen without full hair and make-up these days, says she suffered with bad acne until just three years ago.

"'I had such bad acne when I was younger; I remember it SO well" she revealed on her app this week.

Kendall's skin issues started when she was around 13 or 14, and though acne is a normal part of growing up for many people, the reality star says she found it difficult to cope – especially having grown up in the spotlight.

"'I wouldn't even look at people when I talked to them," she wrote. 

"I felt like such an outcast; when I spoke, it was with my hand covering my face.

"I think I just got acne from being a teenager… but, where it really impacted me was how self-conscious I became about it. It completely ruined my self-esteem."

Over the last 18 months Kendall has worked for Chanel, Balmain, Givenchy and Marc Jacobs among other huge names, but she says it took years to regain her self-confidence.

"Even after things started to clear up, it took a solid amount of time to be okay with my skin and gain back my confidence.

"What I want everyone to understand is that it's been a process: It wasn't anything that happened overnight."

Even now, the model says she gets stressed when she has just "one zit," but she's trying to change her outlook.

"I'm working towards not caring and I'm just in so much of a better place about it all now that I'm older," she said.

"I realised that it's a part of life for some people and it doesn't define who you are."