Hailey Bieber has been suffering from a "flare up" of perioral dermatitis

In a post on Instagram, she shared a picture of the rash around her mouth and wrote: "Always flares up when I'm traveling a lot, sleep deprived, hormones, the wrong SPF, new products, stress."

Hailey went on to explain how she calms her skin down again using prescription medication and products from her Rhode beauty range.

She added: "What I use when I have a flare: so minimal. Rinse my face with water, prescription Azelaic, Hypochlorous acid, Clindamycin, Glazing Milk."

Hailey recently sold her Rhode brand to e.l.f. Beauty in a deal estimated to be worth up to $1 billion, but she'll stay on as chief creative officer and head of innovation as well as acting as a consultant to e.l.f. Beauty.

The influencer recently insisted the arrangement will help her take the products to a whole new level and expand across the world.

She told Glamour magazine: "When you're launching a brand, you're just so focused on what's right in front of you at the time. "And of course, you always have really big dreams and really big goals for it. This is definitely one of those things being realised. I could have never anticipated that it would happen at this exact time ...

"I'm super excited ... I'll be the chief creative officer and head of innovation at Rhode and advisor to Elf Beauty.

"I feel like at this very moment in time, my vision has not been more clear to me. I want to expand globally, and I have so many more dreams and goals that I want to be realised. And I really believe that Elf is going to help us get there."

When asked if there will ever be a "crossover collection" between Rhode and e.l.f. Cosmetics, she replied: "Well, that'll depend on our strategic advisor ... "I'm always open to seeing how we can innovate together. I mean, that is the whole point of all of this. I would say nothing's off the table."