A 23-year-old woman made close to $18,000 in profit in just six months by selling a weight-loss pill called Figure Up for $40 a bottle.
It was touted to be "100 per cent natural" but it was adulterated with undeclared ingredients sibutramine and diclofenac.
Sibutramine has been banned as it can increase the risk of heart attacks and strokes, while diclofenac is a potent painkiller that may cause serious gastric bleeding, heart attacks and strokes when used for a prolonged period.
The self-employed woman was convicted in September last year and fined $9,000.
Another peddler, a 41-year-old system administrator, sold the Nutri Drops Grapefruit Diet, which claims to work in "seven miracle ways" to increase metabolism and burn fats.
The woman took it herself at first and decided to buy it in bulk to sell online. She paid about $41 per bottle and sold it for $65.
Within five months, she sold more than 100 bottles and made an estimated $3,000 profit.
It was labelled as containing only natural ingredients, such as grapefruit, green tea and pomegranate but it had undeclared potent ingredients, such as sibutramine and phenolphthalein. Phenolphthalein can cause abdominal cramps, breathing difficulties and kidney disorders.
One of her clients, an 18- year-old student who wanted to be known only as Amanda, suffered hallucinations after taking Nutri Drops. She weighed over 80kg and wanted to shed the pounds.
She found Nutri Drops through the online marketplace, Carousell, and was thrilled when she lost about 10kg in a month. She was onto her second bottle when things got out of hand.
Her mother said: "She had mood swings, started talking to herself and said she heard voices."
Amanda had to be hospitalised but has since recovered after she stopped taking the pills.
She warned: "Don't take these pills as you are risking your life."
The peddler was fined $7,000 last December.