The blogger was operating a makeshift beauty salon from her flat, offering clients whitening products to make them fairer.
When the Health Sciences Authority (HSA) raided her house following a tip-off, she had three clients hooked to drips, receiving a cocktail of whitening solutions intravenously.
In less than a year, she had found 16 clients after marketing her services on Facebook and made a profit of $17,250. Her clients had paid between $1,500 and $1,800 each for a 10-session package.
The woman in her 30s touted her wares as containing vitamin C and various antioxidants, but one was found to contain a poison called tranexamic acid.
Tranexamic acid is used to prevent or reduce bleeding during surgery for certain conditions and should only be prescribed by a doctor. In July, she was fined $21,000 for the sale of medicine without the required licences. It was the largest fine the HSA had meted out to an online peddler.
Dr Anthony Goon, senior consultant at the National Skin Centre, noted that only medical professionals can administer treatments intravenously. The equipment must also be sterile or there is a risk of infection. The HSA requires cosmetic firms to inform them of the products they plan to sell and to ensure they do not contain prohibited substances.
However, many of the whitening creams sold online illegally by unknown vendors were found by the HSA to contain mercury, hydroquinone and tretinoin - ingredients banned in cosmetics.
Mercury is toxic, while hydroquinone and tretinoin are potent ingredients found in prescription-only medicine to treat skin conditions.
Dr Stephanie Ho, of Stephanie Ho Dermatology, said the use of whitening creams with high doses of hydroquinone has to be monitored by a doctor. This is because some patients experience skin irritation, such as redness, peeling or itching, after using them.
"In Asia, there has long been an emphasis on the beauty of lighter skin and many people will go to great lengths to achieve this," she said. "With online retailers often aggressively marketing their products at very low prices, the temptation is to try to see if it works."
Dr Tan Siak Khim, a general practitioner in private practice, said many of his patients buy whitening creams from various sources to remove blemishes.
Some of them regularly applied creams with high concentrations of hydroquinone for months and patches of skin on their face became discoloured, turning grey or black.
He said: "Instead of getting better, their skin actually got worse."