The 23-year-old model admitted it was “mortifying” when she woke up on her first day of high school and discovered her skin had erupted.
She said: “You feel like it’s the end of the world when that happens.”
The ‘Keeping Up With the Kardashians’ star “really wanted” a boyfriend when she was a teenager but lost all her confidence because of her acne.
She told People magazine: “I literally wouldn’t even look people in the eye when I would speak to them.”
After a few years, Kendall’s skin cleared up but the spots returned when she was 21, which she believes was partly due to stress.
She said: “For me personally, the second time around when it came back, I think it was pretty hormonal.
“You could see it in where I had my breakouts. I also think it had to do with stress. I was having a couple really challenging years of my life.”
The brunette beauty – who has previously spoken of her struggles with anxiety – is finally happy with her skin and is now in a much “better mental place”.
She said: “I’m definitely in a better mental place. It has a lot to do with being clear, but it also has to do with a lot of other things in the way that I’ve changed how my life runs and things that I pick and choose to do. A lot goes into all of that.”
But if she does have a breakout, Kendall tries not to worry too much about it any more.
She said: “It always is frustrating. Always. One zit can really freak you out because you’re like ‘Oh no, are we going backwards again?’ But I try not to think too deeply about it because I know it’s going to be all good. I want everyone to know I’m OK, and you can be OK too.”