Warning issued for diet pills that caused this 21-year-old to "burn up from within".

Image: Parry family.

Last month, university student Eloise Parry died in a UK hospital after taking eight “highly toxic” diet pills she’d bought on the internet.

The tablets, which contained an illicit, industrial chemical called 2.4-dinitrophenol (DNP), had kicked Ms Parry’s metabolism into overdrive, causing it to “explode like TNT”. According to her mother, the 21-year-old started “literally burning up from within” and her heart eventually stopped.

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Ms Parry’s death wasn’t an isolated incident. Last year, these same DNP pills, which retail for up to $200 online, left a French man in a critical condition; while in 2013, they were implicated in the death of 23-year-old Sarah Houston.

Today, following a request from the French government, Interpol has issued an Orange Notice warning about the imminent threat of DNP to law enforcement in 190 countries including Australia.

The illicit substance — which is often used in pesticides and as a raw material in some explosives — can be bought in yellow capsule, cream or powder form for dieting and body-building purposes. According to the IB Times, four deaths in the UK and up to 60 around the world have been attributed to DNP in recent months.

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"In the 1930s DNP was used to boost metabolism and encourage weight loss, but it was taken out of circulation because of several deaths," the Interpol warning states.

"In addition to being produced in clandestine laboratories with no hygiene regulations, without specialist manufacturing knowledge the producers [of DNP] also expose consumers to an increased chance of overdose."

Following the death of Eloise Parry, UK police appealed to the public not to buy slimming substances, or other pharmaceuticals, online.

"Substances from unregistered websites could put your health at risk as they could be extremely harmful, out-of-date or fake," Chief Inspector Jennifer Mattinson said at the time.

Sadly, it was too late for the "very lively" and "bubbly" Ms Parry, whose mother Fiona didn't realise her daughter was using the toxic DNP pills.

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“[The pills] allowed her to achieve this super-slim appearance but it cost her her life... It’s a really nasty drug. Once the drug is in your system it does a lot of damage. It doesn’t just burn fat; it destroys your muscles. It turns bodily fluids yellow," she wrote in an online tribute.

"Most of us don’t believe that a slimming tablet could possibly kill us. DNP is not a miracle slimming pill. It is a deadly toxin.”

Have you ever encountered this substance?