DEADLY diet pills are being sold to teenagers on Instagram for as little as 90p, a Sun investigation has found.

The social media site — which is filled with images of celebrities showing off their slim figures — is allowing dealers across the globe to sell the lethal pills to girls as young as 13.

Some dealers promise the pills, which have been linked to dozens of deaths across the UK, will be on your doorstep in as little as three days.

It comes as a new weight-loss pill dubbed the “holy grail” in the fight against obesity is revealed.

Trials of Lorcaserin have found it to shed pounds while also being the first weight-loss drug ever deemed to be safe for long-term use.

But the drugs being sold on Instagram are anything but safe.

The Sun found dealers were advertising the sale of dinitrophenol (DNP) — an industrial chemical used as a pesticide which has been linked to five deaths this year alone and is illegal for human consumption.

They are also flogging high-risk slimming pills containing phentermine, linked to heart attacks and strokes.

Some sellers post “before and after” shots of young women apparently showing off their dramatic weight loss.

One dealer’s account shows a young girl claiming: “Two months on weight loss journey and 12kg down with the help of Duromine!!!!”

A government study last year found that almost a third of people trying to lose weight have tried unlicensed slimming pills — with 63 per cent suffering serious side-effects including uncontrollable bleeding and heart problems.

Banned DNP works by speeding up the metabolism, but it can lead to slimmers fatally overheating, with users describing feeling as if they are “being boiled alive”.

It has been linked to 23 deaths in the UK since 2012 and last week Public Health England warned that deaths from DNP use are increasing.

In June an online dealer was jailed for manslaughter after supplying the drug to Eloise Parry, 21, who died in 2015 after taking eight pills containing DNP.

Student Eloise, from Shrewsbury, Shrops, bought the drugs from a website run by Bernard Rebelo, 31, of Gosport, Hants, who made more than £200,000 in profit from his sales.

Eloise’s mum Fiona Parry, 55, told The Sun: “Parents should be aware that slimming pills like DNP are available on sites like Instagram. I was not.

“When it comes to dangers like that, the only way you can protect your children is to give them the information and hope they make the right choices.

“You can’t protect them from the dangers if they don’t know they exist.

“Something should be done to stop the availability on the internet. I wish the pills were not available like this but it’s very difficult to stop.

“Governments and politicians have a role in terms of regulating what is out there on the internet.

“It requires cooperation globally to be effective. We are nowhere near that.”

During our investigation an undercover reporter approached one dealer based in Europe via Instagram, who offered 100 DNP pills for £90 — or 90p each — with free shipping and tracking.

The dealer also advised how many to take, messaging: “Start out with one every other day for one week to check for allergies.

"Do that for 1-2 weeks and see how you handle the side-effects.

"Can up the dosage to 400mg/day after that if desired.”

When asked about the side-effects, he replied: “Sweating, insomnia, lethargy are the worst, sometimes cramps due to dehydration.”

The seller later boasted of his quick delivery times, writing: “From what I’ve heard and seen from other UK customers, 3-4 working days.”

Other Instagram dealers were found to be selling phentermine under various names including Duromine, one of the most popular brands of the drug.

Phentermine has a similar effect to amphetamines, causing increased heart rate, raised blood pressure and vomiting.

And while phentermine is legal on private prescription in the UK — after a ban in 2000 was overturned — it is not prescribed by the NHS, as it can cause heart attacks, strokes and impotence.

An overdose can cause hallucinations, seizures, severe headaches, blurred vision and vomiting.

One dealer offered to sell our reporter 30mg Duromine pills at £97 for a box of 30.

He said we should take the pills “once a day every morning before breakfast” with express delivery taking between four and seven days.

Another account was offering to sell 30 pills in a box for £115 including delivery which would take between seven and ten days.

Our reporters were also offered a drug regime known as “Bangkok slimming pills” — a terrifying cocktail of nine tablets a day including appetite suppressants, diuretics, fat burners, laxatives, relaxants and sleeping pills.

A dealer selling these Bangkok pills advised our reporter to try a course of the nine pills each day for 28 days, at a cost of £91.

Under the headline “STRONG” which is for “first timers”, they advised: “30mins before breakfast: 1 blue-clear — appetite suppressant. 1 white/peach — diuretic. 2 purple — Vits. BEDTIME: 30 minutes before sleeping: 2 pink — laxative. 2 green — relaxant. 1 yellow — sleep.”

The Medicine and Healthcare products Regulatory Agency, which controls the safety of medicines, says it has seized £5million of “dodgy diet pills” since April 2013.

Heather Hancock, chair of the Food Standards Agency, said: “We would like to remind people that DNP is an industrial chemical which should not be consumed under any circumstances.

“Doing so could be, and has been, fatal.

"We are relentless in pursuing those seeking to profit from the illegal sale of this toxic substance for human consumption.”

Instagram had not responded to our reporters’ request for a comment at the time of going to press last night.