DNP and diet pills: the dangers of unregulated weight loss medication

Diet pills are not a new phenomenon and have been around since the late 1800s. Often sold for their ‘fat-burning’ properties or ability to suppress appetite, diet pills can seem like a magical weight loss solution.

However, they can be extremely dangerous, and earlier this week, the UK Health Security Agency (UKHSA) announced that 2,4-Dinitrophenol (DNP), a synthetic chemical often found in diet pills, will be reclassified as a poison.

DNP: the lethal diet pills ingredient

The decision was made to reclassify DNP following the deaths of 33 people who died after ingesting the chemical in the form of diet pills. 21-year-old Beth Shipsey was among the people who died after overdosing on DNP, and her parents have been campaigning for it to be banned ever since.

Thanks to this campaigning, from 1 October 2023, DNP will be regulated under the Poisons Act 1972. This means you will need a license from the Home Office to buy it.

The Royal Pharmaceutical Society (RPS) has questioned why the government has not introduced a complete ban, but Security Minister Tom Tugendhat said that the Act makes DNP illegal for all uses (including any industrial uses), which effectively means it is completely banned from the UK.

However, there is concern that the chemical will still be available to buy online, where it is often disguised under alternative names. President of RPS Professor Claire Anderson said: “Including DNP in the Poisons Act is a positive move as it will restrict its availability, but what’s really needed is an outright ban to reduce the risk to the public. Australia has already classified DNP as a substance of such a danger to health as to warrant prohibition of sale and we’d like the UK to follow suit.

“We are concerned that DNP is still in circulation and want to see a firm commitment to prosecuting those who make profits from it. We also call on social media companies to remove content promoting or selling DNP to further reduce harm.”

Table. Annual data — enquiries and fatalities relating to 2,4-dinitrophenol (DNP).

Year	Fatal cases (combined NPIS FSA and ONS data)
2007	1
2008	1
2009	0
2010	0
2011	0
2012	2
2013	4
2014	0
2015	7
2016	2
2017	3
2018	6
2019/20	5
2021/22	2
2021/22	0
TOTAL:	33

Source: National Poisons Information Service (NPIS). *Combined NPIS, Food Standards Agency and Office for National Statistics data

The history of DNP

While DNP is predominantly used in the chemical industry in wood preservatives, herbicides and dyes, it was first used on an industrial scale to make explosives during the First World War. It was here that the chemical’s slimming affects were first realised, with many factory workers experiencing elevated body temperatures, profuse sweating and weight loss.

The observations led researchers to study the chemical in more detail, and Maurice Tainter and Windsor Cutting of Stanford University found that those taking the chemical could lose up to 1.5kg a week without dietary restriction.

Despite the researchers warning of DNP’s potential side effects, around 20 wholesale drug firms began marketing the chemical (a yellow powder predominantly sold in capsules), with many sales occurring through drug stores without prescription or supervision.

DNP was sold over-the-counter as a diet pill to more than 100,000 people before it was pulled from the market in 1938 after a swathe of side effects surfaced, including skin lesions, cataracts and death (due to heightened internal body temperature).

How does DNP work and why is it dangerous?

According to the UKHSA, DNP prevents energy being stored as fat and instead releases it as heat. This increases body temperature which can damage the cells of organs such as muscle, kidney and brain.

The result can be seizures, coma, kidney failure, muscle damage and bone marrow failure. Once these effects have started to develop, they are very difficult to treat and death may occur in spite of the best possible medical treatment.

The UKHSA says it is a myth that taking the substance in small amounts is safe, and it can have fatal consequences even when the user has taken the dose recommended by the manufacturer.

As those who have taken diet pills may not know exactly which chemicals they have ingested, it is important that all healthcare professionals are aware of the signs of DNP poisoning.

Recognising symptoms of DNP poisoning

DNP toxicity can develop over time, meaning patients can take the chemical for extended periods before they start experiencing side effects. However, once side effects begin, patients will need to be referred straight to hospital for treatment.

Symptoms of acute DNP poisoning include: fever, dehydration, nausea, vomiting, sweating, dizziness, abdominal pain, restlessness, flushed skin, sweating, dizziness, headaches, confusion, rapid respiration and rapid or irregular heart-beat. These features can progress to seizures, coma and death.

There is no antidote for DNP poisoning, but TOXBASE guidelines advise those handling emergency cases to quickly introduce cooling measures, fluid resuscitation and sedation to increase the likelihood of recovery.

Healthcare professionals should also ensure the patient has a clear airway, and regularly monitor temperature, pulse and blood pressure. Agitation can be treated with sedation and patients should be observed for at least 12 hours after consuming the drug.

Unregulated diet pills

DNP is not the only dangerous ‘fat-burning’ chemical, and there are hundreds of unregulated diet and weight loss tablets which are available to buy online.

Between April 2013 and November 2017, the MHRA seized nearly £4 million worth of “dodgy” weight loss pills. The products seized by the Agency are not tested for safety and have been found stored in dirty, rat-infested warehouses and garden sheds.

A FakeMeds survey of 1,805 people enrolled on a Slimming World programme revealed that one in three had tried diet pills purchased online. Three quarters (77%) were enticed by promises of rapid weight loss, more than half were attracted to being able to order discreetly (57%) and more than four in ten (44%) ordered online because they didn’t want to speak to a GP or pharmacist, the survey revealed.

However, almost two-in-three (63%) suffered unpleasant side effects after taking the pills, including diarrhoea, bleeding that wouldn’t stop, blurred vision and heart problems. Worryingly, four out of five (81%) didn’t report these side effects to anyone.

How can healthcare professionals safely promote weight loss?

Most healthcare professionals agree that the safest way to lose weight is through eating a healthy, balanced diet and exercising regularly, and GPs (as well as nurses, pharmacists and other healthcare professionals) can offer help and support to anyone looking to lose weight safely.

Any adult with a BMI of 30 or more (or ≥27.5 for people from black, Asian and ethnic minority backgrounds, who are higher risk of type 2 diabetes), and anyone with a diagnosis of diabetes, hypertension or both, can be referred to the NHS Digital Weight Management Programme.

The programme has been designed to offer personalised support and can help people to manage their weight, improve quality of life and improve longer term health outcomes, without needing to travel.

It takes 12 weeks to complete and supports users to develop healthier eating habits, be more active and lose weight, with each plan providing recipes and nutrition advice, wellbeing support and tips to boost your activity levels.

If the patient needs more hands-on support, GPs, nurses and other healthcare professionals can also offer free membership to local weight loss groups, such as Slimming World. Referred patients can attend at no cost to themselves for an initial agreed period (usually in 12 weeks blocks). The cost is paid by Public Health teams or Clinical Commissioning Groups and subsidised by Slimming World, where all weight loss resources are provided.

Is any weight loss medication safe?

If lifestyle changes, such as a moderated diet and exercise, have been ineffective, some patients may be eligible for weight loss medication.

Currently, only one weight loss pill, orlistat, is approved specifically for treating obesity on the NHS. Orlistat (a capsule taken with each meal that contains fat) inhibits the digestive enzymes that break down fat and prevents around one third from being absorbed into the body.

However, the medication can have side effects such as oily and smelly stools, flatulence and frequent needing to go to the toilet. It has also been linked with rare cases of liver injury.

Orlistat is therefore only prescribed to people with a BMI of at least 28 that have failed to lower their weight through natural methods.

Patients with type 2 diabetes who are obese and have struggled to lose weight may also benefit from certain drugs that facilitate weight loss such as incretin drugs, SGLT-2 inhibitors or alpha-glucosidase inhibitors.

Similarly, Ozempic (semaglutide), a drug used to treatment adults with type 2 diabetes, has also been shown to promote weight loss. It helps to improve blood sugar and lower haemoglobin A1C, as well as regulate appetite by creating a feeling of fullness.

Just last year, there were worldwide shortages of the drug after it took the social media platform TikTok by storm, with many young women, who are not diabetic, beginning to use the drug for weight loss purposes.

While Ozempic has been shown to be effective for diabetic people, particularly those who are obese and overweight, the drug’s side effects are much less researched on other groups.

Learning and developing new, healthy habits is the “best way to lose weight”

Even when drugs have been thoroughly tested and approved, there is still a risk of side effects appearing when taken over an extended period of time. According to The Independent, at least 25 weight loss drugs have been approved by medical authorities in the past 60 years, only to be banned once their side effects were realised a few years later.

For this reason, experts generally agree that the safest way to lose weight is through moderating diet and exercising, as Jenny Caven, Slimming World’s Head of External Affairs, explains: “It’s easy to see how quick fix promises made by the sellers of online slimming pills could seem tempting to people who are desperately struggling with their weight.

“Buying slimming pills online can be incredibly risky though. The sellers are often unregulated and taking the pills puts people at risk of dangerous side effects. Learning to make changes to the way you shop, cook and eat and getting support to develop new healthy habits really is the best way to lose weight. Not only is it safer, it’s also far more satisfying and has the added benefit that newfound habits can be passed on to the people around you too. Getting support makes your new habits more likely to stick in the longer term and you won’t suffer any nasty side effects.”