A new product said to make women's intimate areas "fairer within four weeks" has revived the beauty debate in colour-conscious Thailand, where fair skin is associated with opportunity, success and status, and caused critics to question when, if ever, the skin-whitening craze will end.

Products promising to lighten the face, body and armpits are already available across the country, with skin-whitening pills and diet supplements claiming to pick up where the cosmetics leave off. But this is the first time that a vaginal whitening wash has hit the Thai market.

In the adverts, which are available online, on TV and on radio, a fair-skinned woman in skinny jeans wanders into her closet to change clothes, describing how "everyone wants to look good – but tight shorts can leave your skin darker". The camera then zooms in on her new outfit, which includes a pair of white shorts, to a voiceover claiming that Lactacyd White Intimate can make skin in that area become "bright and translucent".

The launch of a similar product in India this year was met with international disdain after a TV advert insinuated that having a fairer vagina would make women more attractive to men. In Thailand, however, the companies responsible say they have been successful. "Products [have] evolved from face-whitening to body and deodorant solutions to even out dark areas in the armpits," said Louis-Sebastien Ohl of Publicis Thailand, which created the adverts. "Now an intimate toiletry also offers a whitening benefit, because research evidenced that … women [are] keen to have such a product."

In many countries across south-east Asia, fairer skin is equated with higher class as it suggests a life not spent toiling in rice paddies under the sun. The Thai language is peppered with expressions that denigrate dark skin, such as the insult dam mhuen e-ga – "black like a crow". These days, rice farmers wear long sleeves, trousers, wide-brimmed hats and gloves. According to DRAFTFCB, the agency behind many of Nivea's skin-lightening ads in Thailand, such labourers make up the bulk of the Thai market for Nivea's face- and body-lightening products.

Using pale Korean and Japanese pop stars as illustrations, Thai women's magazines are full of fair-skinned Asians promoting products that promise to whiten, lighten and "boost" the complexion, with slogans such as "Show off your aura" and "Get to know the miracle of white skin". Fair-skinned actors and singers dominate the media nearly all over the Asia-Pacific region, where the skin-lightening industry is expected to reach $2bn this year , with the fastest growing markets in China and India.

But the trend has been associated with health risks as many products contain ingredients such as hydroquinone and mercury, which can lead to permanent skin discolouration or kidney damage. Some products are illegal. There is no suggestion that Lactacyd White Intimate or Nivea products are illegal or contain hydroquinone or mercury.

Critics of the whitening trend, such as Kultida Samabuddhi of the Bangkok Post, who wrote a opinion piece on the whitening feminine wash, say such products have changed the country's value system.

"As the definition of beauty has been changed by cosmetic industry, Thai women who fail to meet the beauty standards set by cosmetic producers and ad agencies have to struggle very hard to maintain their self-esteem," she told the Guardian.

But the skin-whitening craze looks set to continue. The male market is yet to be fully tapped, said Ohl, who added that future variants of Lactacyd White Intimate would be formulated to include anti-ageing properties, "so you can keep intimate parts fresh and young" as well.