Illegal peddlers selling the appetite suppressant Duromine on the Internet have become more brazen in recent years.
Not only are there more of such sellers online, many are also demanding higher prices for the prescription drug.
The Sunday Times found at least 13 who have surfaced on Internet forums over the last year or so. Between 2006 and 2011, there were only about seven active sellers.
One of these unauthorised sellers asked for $400 for 15 pills, or more than $26 per pill - the highest price found for the drug online. The lowest was $4.33 a pill. A patient with a prescription pays between $2.70 and $3.50 per pill, including a GP's consultation fees.
The active ingredient in Duromine is phentermine, a chemical that regulates food intake by inducing a feeling of fullness. Besides Duromine, phentermine is sold as Panbesy. These are the only two appetite suppressants prescribed by doctors here.
Phentermine last made headlines in 2009 after the Ministry of Health warned doctors to be more stringent when dispensing such drugs to patients who may not necessarily need them.
The ministry said in an advisory then that Duromine should not be prescribed to those with a Body Mass Index (BMI) lower than 27. Doctors should also dispense the drug at the lowest possible dosage and keep detailed patient records when doing so.
A person is obese when his BMI is 30 or higher. To calculate BMI, divide your weight in kilograms by the square of your height in metres.
Although the drug is meant for the moderately and severely obese, those who scour the Internet for Duromine typically have a relatively low BMI.
Dr Daniel Wai, an endocrinologist from Daniel Wai Diabetes, Thyroid and Hormone Clinic, said he has noticed more younger female patients asking for Duromine since last year. Most, he added, had a normal BMI.
"The problem is that these young girls are influenced by thin models who appear in lifestyle magazines," he said.
Online forums remain a treasure trove for buyers who cannot get a doctor to prescribe the drug.
A seller, who spoke on condition of anonymity, said many young girls do not visit doctors "because they know they are not that fat". Desperate to achieve a "skinny model look", many young girls resort to paying the sky-high prices demanded by peddlers for Duromine.
When The Sunday Times, posing as a buyer, asked a seller why there was such a vast difference in his price, the seller cited "a shortage of stocks" and "restricted quota production" from the manufacturer as the reason for its higher-than-normal price.
A spokesman for Australian-based manufacturer iNova Pharmaceuticals, which produces Duromine, said there was "no such restriction" and that "sales are going as per normal with our local distributor".
Duromine is distributed by Zuellig Pharma here.
Those caught selling Duromine illegally could end up with a $5,000 fine and/or a two-year imprisonment term.
Fourteen have been hauled up to court by the Health Sciences Authority (HSA) for the illegal sale of health products between 2010 and this year.
There have also been six hospitalisations related to the consumption of slimming products since 2010.
HSA said that because it is impossible to completely eradicate online sales, "the public plays an important role in reducing the demand for such products".
Products bought online from unauthorised sources also run the risk of being counterfeit or containing harmful substances, warned doctors.
For instance, the consumption of Duromine must be supervised by doctors, as side effects include heart palpitations, mood swings, severe nausea and a compromised immune system. Also, a patient should not be taking it for more than six months.
A 26-year-old public relations executive, who took Duromine she had purchased online, said that while she did lose weight, the side effects she suffered were not worth it. "I wouldn't dare take it if I knew I would end up with poor liver function."
