For many of us, face masks have become an essential part of everyday life thanks to the coronavirus. But regularly wearing one can have an unfortunate side-effect: mask-induced acne, aka "maskne".

"Maskne is absolutely real. No questions asked," Dr Mona Gohara, Associate Clinical Professor of Dermatology at the Yale School of Medicine, told the BBC.

"I wear two masks and sometimes a protective shield… [and] have myself experienced it and continue to experience it."

It's a frustrating scenario that anyone who's had unwanted spots can probably sympathise with.

But what exactly causes maskne?

According to dermatologist Angeline Yong, the "constant rubbing of the masks against our skin causes micro-tears, allowing easier entry for bacteria and dirt to clog up our pores".

And then there's that moist, damp environment going on underneath your mask.

"Breathing into a mask also creates a hot and moist environment that leads to the build-up of sweat, oil and bacteria. Add on the fact that face masks are occlusive [designed to block things] by nature, and it's a recipe for skin disaster," says Dr Yong, whose practice is based in Singapore.

Dr Yong says she tells her clients one way to combat maskne is to "avoid thick, occlusive skincare creams".

"I always tell my patients to opt for more lightweight water-based products underneath the mask... a lightweight moisturiser can also act as an additional protective barrier and prevent chafing," she says.

"Ideally, you should [also] be using a mild and gentle exfoliator to ... support the absorption of your moisturiser."

Perhaps unsurprisingly, skincare companies have been quick to recognise the rise of maskne.

Popular Korean skincare brand Dr Jart now has a special "Maskne Essentials" category on its site - with items like a "facial barrier mask" and an anti-blemish patch.

Even skincare cult favourite Dr Jart has jumped on the maskne bandwagon Image copyright Dr Jart

Jochen Zaumseil, L'Oréal's executive-vice president in Asia-Pacific, said popular skincare brands like La Roche-Posay and CeraVe had seen a "huge boom" recently - with a rise in demand for products like cleansers and sheet masks.

In Asia-Pacific, this rise in deep-cleansing products was attributed to mask-related issues, including issues like oilier skin and acne, as well as an increase in hygiene habits due to Covid-19.

"Skincare has always been by far our number one [revenue driver], [but] of course that's shifted even further [ahead] during the crisis," said Mr Zaumseil.

But while skincare is booming, the makeup industry has taken a hit as more people work from home and avoid heading out.

Mr Zaumseil says demand for makeup is expected to rise again as life returns to normal, businesses begin to re-open, and more people start going into work.

According to L'Oréal, this is what it's witnessed in China, which is several months ahead of most of the world in coping with the virus.

It found that some 34% of Chinese women wore makeup in February, during the peak of the lockdown - this figure has now increased to 68% in late June to early July.

However, L'Oréal says there's been a consistent demand for products that show up above people's face masks.

"The eyes are the most visible part of your face now, [so] mascara, eyeliner, these are doing very well," said Mr Zaumseil.

Lightweight products are proving popular, as are long-lasting, non-smudge lipsticks that will not transfer onto masks.

'Contouring is out, eyes are in!'

On YouTube, the trend has echoed across the beauty industry, and a growing number of vloggers are making mask-friendly makeup tutorial videos.

Heavy contoured looks are out, and bold eyes are in.

"You're focusing more on eyebrows, eyeshadows - because you do have something that covers half your face. I like really bushy eyebrows and a really bold, colourful eye palette, just glamming up the eyes to help you stand out," US YouTuber Melina Basnight told the BBC.

"I also put on some light makeup on the rest of my face because there are times you take off your mask when you go outside. I've kinda perfected what works."

Ms Basnight, who is a discharge assistant at a Texas hospital, is required to wear a mask every day at work.

"[Earlier this year] I had a few people asking me how [to put on makeup with a mask] and at that point I had already been wearing masks for a few weeks," she said.

"A lot of people still want to wear makeup even with their masks. It just provides a sense of normalcy. At a time where nothing is normal, it's just that tiny thing you can hold on to."

So she decided to create a mask-friendly makeup tutorial on her MakeupMenaree channel.

Filipino YouTuber Nina Carpio said she was inspired to focus on the issue back in May - after experiencing first-hand the damage a full face of makeup dealt to her skin.

The combination of makeup and perspiration under a mask, she says, irritated her skin and caused her pores to clog. The makeup also transferred to the underside of her mask, dirtying it.

"I tried putting on a full [face] of makeup with foundation, powder, contour… I found it will not work. [So for now] I skip everything. I put on the face and lips, and just put products like moisturisers and lip balm," said the YouTuber, whose channel is Smile Like Nina.

And this trend, she says, is expected to continue for the foreseeable future.

"As long as we are still living in the pandemic, face masks will become part of our everyday - and so [our] makeup looks will definitely revolve around it." BBC