It's the kind of promise that stops thumbs mid-scroll: "Take Molecule and forget food exists." Viral TikTok clips show influencers flaunting rapid weight-loss transformations, tapping into the body image concerns that leave many young people struggling with what they see in the mirror.
Author
- Dipa Kamdar
Senior Lecturer in Pharmacy Practice, Kingston University
These perceived imperfections are increasingly being addressed through quick fixes - pills and injections that promise effortless change. In the US and UK, weight-loss drugs such as Ozempic and Wegovy dominate the headlines. But in Russia and eastern Europe, a different trend is emerging.
Young people are turning to a drug called Molecule, with some sharing their experiences in a recent BBC report. Behind the social media hype lies a troubling truth: Molecule contains a compound banned in the UK, EU and US for its dangerous side-effects.
The ingredients purported to be in Molecule include dandelion root, fennel seeds and black tea - benign-sounding botanicals that disguise what tests have actually found. These pills contain sibutramine, a substance with a chequered regulatory history.
Sibutramine
Sibutramine was originally sold on prescription under the name Reductil and was widely used to help people lose weight. It works by altering brain chemicals that control hunger. Specifically, it increases levels of serotonin and noradrenaline in the part of the brain that signals when you feel full - meaning people feel satisfied faster and eat less.
Sibutramine can also slightly increase how quickly the body burns energy and prevent metabolism from slowing during weight loss. Together, these effects can help people lose weight and make it easier to maintain that weight loss.
In one study , people who were overweight or obese lost 5-10% of their body weight when they used sibutramine along with consuming fewer calories, exercising regularly and getting support to change their habits. However, the drug's use declined as more evidence emerged that it could increase the risk of serious heart problems.
In 2010, the European Medicines Agency stopped allowing sibutramine to be prescribed after the results of the large Scout trial were published. This study showed that the drug raised the risk of heart attacks and strokes, particularly in people who already had heart problems.
The US and the UK's drugs regulators followed suit, citing that the risks outweighed the benefits. The decision was unequivocal: sibutramine was too dangerous for general use.
The side-effects of sibutramine are not just theoretical - they're well-documented and potentially life-threatening. Common reactions include dry mouth, constipation, insomnia and headaches. But more worrying, the drug can raise blood pressure and make the heart beat faster by stimulating the body's "fight or flight" system.
This adds extra strain on the heart, which is particularly risky for people who already have heart or circulation problems. In more serious cases, it can lead to a heart attack or stroke.
Serotonin syndrome
Sibutramine can also interact in dangerous ways with other drugs, which many people taking it may not realise. For example, if it is taken alongside certain antidepressants - such as monoamine oxidase inhibitors or selective serotonin reuptake inhibitors - it can trigger a condition called serotonin syndrome.
Both drugs raise serotonin levels, and if those levels become too high, it can cause a serious and potentially life-threatening reaction. The same risk can also occur if sibutramine is taken with some migraine medicines, such as sumatriptan, or certain opioid painkillers, such as fentanyl.
Serotonin syndrome can cause symptoms such as confusion, restlessness, sweating, fever, a fast heartbeat, muscle spasms and problems with coordination.
Sibutramine is processed by enzymes in the liver, so it can also interact with other medicines that are broken down in the same way. Some antibiotics such as erythromycin and antifungal drugs such as ketoconazole can block these liver enzymes, thus raising the levels of sibutramine and increasing the risk of side-effects.
In Russia, sibutramine is still available with a prescription for treating obesity in adults. Yet sibutramine continues to surface in unlicensed supplements, including Molecule, often sold under misleading labels proclaiming them "natural" or "herbal" and sold online or through informal channels.
These products bypass regulatory scrutiny, making it difficult for consumers to know exactly what they're taking. The accessibility is deceptive: what looks like a harmless supplement bought from a seemingly legitimate online seller may contain a banned drug that can cause serious harm.
This comeback shows just how risky unregulated diet pills can be and why it is so important to check that any supplement is safe and legal before taking it. The story of sibutramine is a warning: even medicines that were once approved can have hidden dangers, especially if they are misused or sold illegally. And the promise of easy weight loss often comes with a cost much higher than what is listed on the label.
Dipa Kamdar does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.
