The insatiable quest for beauty has fuelled the growing popularity of whitening creams, muscle-building steroids and weight-loss pills sold illegally online, displacing sex drugs and birth control pills as the items foremost on the radar of the national regulator for health products.

More than 900 people - including a 14-year-old - were caught by the Health Sciences Authority (HSA) for peddling health products illegally on the Web from 2011 to last year.

Now the top products on HSA's probe list are: weight-loss products; anabolic steroids to build muscle mass; whitening creams; and medical devices such as contact lenses, pregnancy test kits and condoms.

There is growing interest in these items and more people have alerted the HSA about such products, its spokesman said.

A decade ago, contraceptive pills, weight-loss products and sexual-enhancement drugs were of top concern, Dr Dorothy Toh, HSA's assistant group director of health products regulation, told The Sunday Times.

On the popularity of whitening creams sold online, she said : "Everyone wants to be fair and there are all these advertisements equating beauty with fairness, to look like a Japanese or Korean star."

Doctors said a key reason people turn to online peddlers is that they cannot get these prescription-only medicines from them.

For example, weight-loss pills are not prescribed for someone who is not overweight.

Anabolic steroids too can only be prescribed by doctors to treat, for example, muscular degenerative diseases. Dr Tan Kok Kuan, of Dr Tan & Partners, said: "Anabolic steroids are popular among young gym-going men who want to beef up. But no doctor will prescribe it just for them to look good."

The abuse of such steroids can cause liver, kidney or heart damage, among other problems.

From 2011 - when the HSA started keeping records of those caught selling health products illegally online - to last year, the authority caught 939 people and seized 350,000 items.

The youngest caught was a 14-year-old student who sold contact lenses for between $8 and $12 a pair through her Facebook page to make extra pocket money.

The HSA seized 243 pairs of contact lenses from her house.

The first-time offender was let off with a warning.

Of those caught, 40 people were charged in court and one man was jailed. The rest were let off with a written warning or fined, among other things.

The offender who drew jail time was brazenly peddling sex drugs with names like Black Deity and Magic Penis on an online forum, even while being investigated by the HSA. Over 36,000 pills containing prescription-only medicine to treat erectile dysfunction were seized from his home. They had a street value of close to half a million dollars.

He had imported them for between $20 and $90 a box, and sold them for $35 to $120. He was jailed for 18 weeks in April.

The HSA's Dr Toh said illegal online sales of health products is a growing concern, as the safety and quality of the items sold by unknown vendors is questionable.

Some people have suffered serious complications, from hallucinations to liver failure, after taking slimming products bought online. One woman died.

Dr Toh said that instead of blogs and forums, many of today's peddlers market their wares on e-commerce sites and social media.

Many deliver their wares by mail or courier, which makes it more convenient for clients. A decade ago, the buyer and seller often met up to transact. Those caught selling illegal health products can be fined up to $100,000 or jailed up to three years, or both.

She urged consumers to be wary of health products sold online that promise quick and miraculous results or even those that claim to be 100 per cent safe.

She stressed that these products could be fake or adulterated with banned or undeclared potent ingredients that can cause harm. "Do not gamble with your health," she said.