Drinking a local brand of "organic orange juice" could give you a heart attack, stroke, or loss of hearing or vision because it contains strong medicine used to treat erectile dysfunction, the Health Sciences Authority (HSA) warned yesterday.
It has found "undeclared potent chemical ingredients" in four S Lion Juice products sold online.
One of them, S Lion Juice 10g, contains tadalafil, the active ingredient in Cialis - a prescription drug used to treat erectile dysfunction.
The other three had chemically related compounds of this drug or sildenafil, which is sold as Viagra.
HSA said: "These products carried claims such as 'increase energy and stamina', 'improve sleep quality', 'improve brain functionality', 'strengthen bones, prevent osteoporosis', and 'help menopausal women regain their emotional health and strength'."
However, tests found they contained various medications for male erectile dysfunction.
Such medicine, it said, is "not suitable for women and certain men, including those under 18 years of age, and patients with heart-related problems or who are on heart medications such as nitrates".
There have been reports in other countries of deaths in men who take such drugs while also taking nitrates to treat heart problems.
HSA urges people who have bought these juices to stop taking them immediately and to see a doctor if they do not feel well.
The authority added: "HSA is currently investigating the sellers of these illegal products and will take strong enforcement actions against individuals who engage in the sale and supply of health products containing undeclared medicinal ingredients."
An HSA spokesman said the prescription drugs in the drinks were discovered after the local company, S Management Products, sent the juices for testing.
It is not known why it had done so, especially as the company claims on its website that it makes all its products "based on intensive research, consultation with experts, testing and proven results". The company added: "All our products are manufactured, tested and certified in Singapore."
The firm said its products are sold in Singapore, Malaysia, Indonesia and China.
HSA has issued a warning for consumers to be wary when purchasing health products from dubious online sites.
It said: " When buying health products online, buy them only from websites with an established retail presence in Singapore."
The spokesman added that the company has agreed to stop sales of all four products.