IT IS advertised as a healthy sweet, but a dangerous substance has been found in 'Mentalk' candy.

The Health Sciences Authority (HSA) laboratories issued an urgent alert yesterday after detecting the potentially fatal chemical, aminotadalafil, in the candy.

It is believed that the candy is sold through the Internet via www.mentalk2u.com, and possibly through multi-level marketing.

Aminotadalafil is chemically similar to tadalafil - an ingredient of the anti-impotence drug Cialis.

It can cause heart attacks and strokes in some people. For heart patients on certain drugs, it could trigger an abnormally low blood pressure which could kill.

The substance was detected on Thursday afternoon, said the HSA.

Follow-up action and coordination with relevant agencies to determine the distribution and sale of the candy started that night and was underway, it added.