An unknown number of unsuspecting dieters are thought to have bought a deadly 'fat-burner' tablet that has killed a young Irish man.
The yellow-coloured 'miracle diet pills', which come in a white tube with the label DNP 200 and contain Dinitrophenol, led to the death of the man last month.
Another 93 of these pills were seized by gardaí and officials of the medicines watchdog the Health Products Regulatory Authority (HPRA) recently.
However, the full extent of the availability of these weight-loss tablets, which are purchased online, is unknown.
HPRA chief Pat O'Mahony warned consumers that products containing Dinitrophenol are not fit for human consumption and have the potential to cause serious harm.
He repeated that people should not buy slimming products which may be illegally available online.
Some of these products have dangerous chemicals which are often undeclared on the pack.
Anyone who has taken these pills and are suffering any ill effects should contact their doctor immediately.
Warning signs include hot dry skin, excessive thirst, severe sweating, an abnormally fast heartbeat and rapid breathing.
Mr O'Mahony said: "Any remaining quantity should not be taken and can be collected by the HPRA for disposal.
"The information we have at this time indicates that this young man consumed DNP and our thoughts are with his family.
"These investigations are on-going. No amount of these products is safe to take.
"Bogus websites can be very sophisticated and appear to be legitimate.
"However, in reality they can be supplying unsafe and harmful products."
Mr O'Mahony added: "Laboratory analysis of products detained in the past has shown that medicines being sold through illicit websites will often contain too little or too much of the active ingredient or may contain undeclared and harmful substances."
Another tragic death linked to the diet pills was reported in the UK in April, sparking a major alert.
It recently emerged that hauls of illegally imported steroids are making their way on to the market here and are being sold in gyms, where people are involved in body building.
Interpol have also issued a global alert over the threat posed by the so-called diet pills after they claimed the life of a British woman.
The world police agency raised the alarm with forces in 190 countries as the toxic pesticide was linked to the death of Eloise Parry, of Shrewsbury, Shropshire, while a Frenchman was fighting for his life after taking the drug.
Eloise Parry, 21, died at the Royal Shrewsbury Hospital in April after taking tablets she bought online.
Police believe they included a quantity of DNP.
A study last year warned the drug, which is also sometimes used as a bodybuilding aid, could be linked to five more deaths in the UK between 2007 and 2013.
In an Orange Notice issued by Interpol, at the request of French health authorities, the agency declared an "imminent threat'' to consumers from DNP, which has also been used in explosives.
Online distributors have even tried to mask its supply from customs and police officers by labelling it as the yellow spice turmeric because it looks similar.