In the heart of Sydney's Chinatown, 30-year-old retail assistant Amanda is selling face masks and creams in bright packages. But it is the skin-whitening products that have her attention.

"Chinese people like whitening, [they consider it] beautiful — whitening and brightening because it's good," she says, smiling.

The smile is genuine, as Amanda is a fan herself.

"I use this one in the morning and at night … it can make your skin look very healthy, very clear," she says.

"It's very popular."

The products appear to be becoming more popular in Australia. ( ABC News: Thuy Ong )

And this popularity is on the rise with the market for skin lighteners projected to reach $US23 billion ($30.5 billion) by 2020, according to market intelligence firm Global Industry Analysts.

Across Asia, it is normal to walk into a beauty store and see mostly skin-whitening products adorning the shelves.

Whitening is a cultural trend and derives from what's known as "colourism" — a system that privileges lighter skin.

It can be pervasive in Asian cultures where darker skin is often associated with manual outdoor work like farming, and therefore a lower status.

According to the Australian Bureau of Statistics' latest census data from 2011, 24.6 per cent of the population was born overseas, while 43.1 per cent of people have at least one overseas-born parent.

"I think this sort of population shift has actually resulted in an uptake in potential purchase of skin-whitening agents and certainly in my practice as a dermatologist that specialises in pigmented skin and coloured skin, I've seen a growing number of consultations and queries," Dr Michelle Rodrigues from the College of Dermatologists and a consultant dermatologist in Melbourne said.

"The majority of patients that see me about lightening have a preconceived idea that this is more beautiful and this stems from very deep-seated cultural and historical beliefs that perhaps this leads to increased employment or marital opportunities."

While there are no national figures, pharmacies and beauty stores the ABC spoke to said the sales of whitening and brightening creams, scrubs, lotions and even pills were increasing.

Dermatologists are concerned product packaging is in foreign languages. ( ABC News: Thuy Ong )

"You get your dark-skinned people who tend to spend a lot of time out in the sun and then suddenly just want something to help lighten their skin, because they don't like the look of it, and it's a trend as well," Priceline cosmetician Vali Harding told ABC News.

Ms Harding estimates sales of the products have doubled over the last 12 months at the Adelaide pharmacy where she works.

Albina Reale, the national category manager for fragrance and beauty at Chemist Warehouse, agrees.

"The whole mask trend in skincare is across all categories but in particularly in whitening — that's the fastest-growing trend and you can see that coming out of Korea and China. It's definitely on trend, and it's definitely something that we've had to focus on," she said.

"Asian cultures like white skin — it's [considered] beautiful, young," Penna, an assistant at Blush Cosmetics in Sydney's CBD, said.

Penna said she used a Japanese whitening lotion each morning and planned to continue.

Beauty stores the ABC visited in Sydney said women regularly purchasing whitening products were aged between 25 and 40.

Dermatologists warn of side-effects, unknown ingredients

There are thousands of videos on YouTube regarding DIY methods of whitening from everyday products, to extensive reviews on how well certain brands work.

Dermatologists in Australia said they were concerned about the risks of using the products where some ingredients were not clearly disclosed or were in foreign languages.

"There has been a slow but gradual increase in the number of patients using these and therefore the number of side-effects," Dr Rodrigues said, adding one of her patients had had issues with irritation and redness after using whitening creams.

"There are real risks and only theoretical benefits that haven't been proven but have shown to be potentially dangerous."

The Therapeutic Goods Administration (TGA) said the chemical hydroquinone was the most commonly used ingredient in skin-whitening products.

The chemical is banned in Europe, but can be found in products sold in Australia.

Since 2000, there had only been six adverse drug reactions related to the use of hydroquinone recorded in its database, the TGA said.

However, doctors said there was a broader need for education about identity and self-care.

"It does beg a wider more philosophical question about darker-skinned people trying to look Anglo-Saxon, which is a concern I think," Dr Ritu Gupta, a specialist dermatologist based in Sydney, said.

"It is very worrying."