SINGAPORE - At 47kg, Gillian (not her real name) was healthy but haunted by the image of herself as an overweight teenager.

She wanted to be 45kg.

The 24 year-old, who is 1.6m tall, turned to Malaysian slimming drink Bello Smaze, which had pages of glowing testimonials on Facebook.

But within four days of consuming it, she developed palpitations, insomnia and subsequently suicidal thoughts. She stopped taking it immediately.

"On my first day, I broke out in cold sweat a few hours after drinking it. I don't suffer from depression but suddenly, I had suicidal thoughts and was overwhelmed by my past of being bullied for my size," she told The Straits Times.

Gillian said she was swayed by the many success stories she read online. "The seller even sent me a certificate in Malay that she said is from the Malaysian authorities stating Bello Smaze is safe."

But tests by Singapore's Health Sciences Authority (HSA) found it has a banned weight-loss substance.

Called sibutramine, it can cause mood swings, hallucinations, heart attacks and strokes, said Associate Professor Chan Cheng Leng, group director of the health products regulation group at HSA.

It is among four health products the HSA has alerted people to on Monday (June 3) after five consumers reported adverse reactions to them, including one woman who now has severe heart failure.

Three of them are for weight loss: BB Body, Bello Smaze, Choco Fitare. The fourth is Seahorse Chop Du Zhong Ba Ji Wan, which has a potent steroid called dexamethasone, it said in a statement.

In one of the more severe cases, a woman in her 50s who bought BB Body from an online seller in Malaysia developed an extremely fast heart rate after taking the product for about three months.

She lost consciousness, the HSA said, adding that she came across the product on Instagram.

Cardiologist Lee Chee Wan, who treated her, told The Straits Times on Monday that the woman has had a defibrillator implanted to regulate her heart rhythm as her heart is likely to fail again within a year.

She also requires long-term heart failure medication.

Her case is one of the worst Dr Lee said he has heard of."Most slimming products either don't work or are unsafe. Even if you do check the ingredient list, some products do not declare that they contain harmful substances," he added.

In a separate case, a woman in her 30s had palpitations after consuming Choco Fit for two days.

The HSA said the adverse reactions of the women were consistent with the effects of sibutramine, which it had banned in 2010 due to an increased risk of heart attacks, strokes and other serious effects.

BB Body, Bello Smaze and Choco Fit were marketed on various e-commerce and social media platforms, such as Instagram and Facebook, as having "no side effects" or can deliver weight loss in days.

The HSA said it has directed the administrators of the local online platforms to remove the product listings.

It said: "HSA monitors local websites and e-commerce platforms which sell medicines or suspected illegal health products. We work actively with the web administrators to take down postings and educate sellers on the illegal sale of health products."

It also works closely with overseas regulatory agencies and international counterparts like Interpol for information sharing on illegal health products.

But experts say it is difficult to regulate online transactions of these products.

Mr William Chen, Michael Fam Chair Professor in Food Science and Technology, and Director of the Nanyang Technological University Food Science and Technology Programme, said: "Similar cases are expected to surface more frequently with the increase in online shopping."

He added: "While our HSA has put in place robust inspection procedure for health products and ingredients, it may not be practical to implement such inspections on products purchased online and from overseas sources."

Assoc Prof Chan of HSA urged people to be wary of claims or promises of quick weight loss when buying health products, whether online or in retail shops.

"Based on HSA's enforcement operations, many of the weight loss products sold on e-commerce platforms without an established retail presence were found to contain the banned substance, sibutramine," she said.

In the statement, the HSA also warned against Seahorse Chop Du Zhong Ba Ji Wan, which led to Cushing's syndrome in a man in his 40s.

He had bought the product from a medical hall in Johor Baru and took it for more than two months to relieve his arthritis. He suffered a "moon" face, thin limbs, thinning of the skin and easy bruising.

His condition was caused by dexamethasone, a potent steroid that was fraudulently added into the product.

Dexamethasone is usually prescribed for inflammatory conditions. Long-term unsupervised use of oral steroids can cause increased blood glucose levels, which may lead to diabetes. It can also cause high blood pressure, cataracts, muscular and bone disorders, an increased risk of infections and Cushing's syndrome.

HSA tests also found that the Seahorse product contained chlorpheniramine, which is an antihistamine for allergic reactions, such as hay fever, rhinitis, urticaria and asthma.

This medicinal ingredient can cause adverse effects such as drowsiness, nausea, vomiting, diarrhoea and constipation.

The HSA found blister strips in one of the boxes carrying a different product name and labelled as "100% Natural Pure Herbal * Acti Fast", which it pointed out was another sign the product was illegal.

Tests on the product showed that it contained an additional adulterant, frusemide, which is a potent medicine for removing excess water and salt in the body.

When taken in excess, frusemide can cause the depletion of sodium, chloride, body water and other minerals in the body.

"These findings are characteristic of illegal products which are manufactured without any quality control," the statement said.

HSA advises consumers to stop taking Bello Smaze, BB Body or Choco Fit immediately and consult a doctor if they feel unwell.

As Seahorse Chop Du Zhong Ba Ji Wan contains a potent steroid, consumers who have taken it should see a doctor as soon as possible.

Discontinuation of steroids without proper medical supervision can cause serious withdrawal symptoms such as fatigue, confusion and low blood pressure, especially if the consumer had taken the product for a few weeks.

HSA advised consumers to be wary of health products that promise or deliver quick and miraculous effects, or carry exaggerated claims.

Consumers should also avoid buying health products from unfamiliar sources overseas, and be cautious when buying such products online as it can be hard to be certain where and how these products were made.

The products could potentially be counterfeits or contain undeclared ingredients which can seriously harm a person's health, the HSA said.

HSA also advised sellers and suppliers to stop selling the products immediately.

Anyone convicted of selling them may be jailed up to three years or fined up to $100,000.

Those with information on the sale and supply of illegal products may contact the HSA's enforcement branch on 6866-3485 during office hours or e-mail hsa_is@hsa.gov.sg

Meanwhile, the side effects Gillian experienced subsided a week after she stopped taking Bello Smaze.

She said: "I won't be taking these kinds of products anymore and will stick to exercising."