Jun 09, 2026 - Three people in their 20s and 30s living in Osaka Prefecture and other areas were referred to prosecutors on June 2nd for allegedly illegally selling and transferring the type 2 diabetes drug Mounjaro without the required authorization, as concerns grow over the drug's popularity as a weight-loss treatment and the health risks associated with its misuse.
Mounjaro was approved by Japan's Ministry of Health, Labour and Welfare in 2022 as a treatment for type 2 diabetes. Unlike insulin, which often requires daily injections, Mounjaro is administered once a week while maintaining its effectiveness, significantly reducing the burden on patients.
For many diabetes sufferers, the drug has become an essential part of treatment. However, police allege that the three suspects sold and transferred Mounjaro through social media despite lacking the necessary pharmaceutical sales licenses. The case marks the first known crackdown on illegal Mounjaro sales in Osaka Prefecture.
The drug has gained widespread attention online as a so-called "slimming injection." Because it suppresses appetite and prolongs feelings of fullness, some cosmetic clinics prescribe it for weight-loss purposes as part of medical dieting programs.
As the treatment is not covered by insurance when used for dieting, patients typically pay between 5,000 yen and 7,000 yen per injection. The drug has become particularly popular among younger women, with social media filled with posts praising dramatic weight loss.
Some users reported losing around five kilograms, while others described being surprised by the drug's effectiveness. Investigators believe the three individuals referred to prosecutors took advantage of this popularity by reselling the medication for extra income.
Doctors specializing in diabetes treatment warn that growing demand for non-medical use could make it harder for patients with diabetes to obtain a drug they genuinely need.
One physician expressed concern that supplies of an important medication could be diverted to people using it inappropriately, creating risks for patients who depend on it for treatment.
Medical experts also caution that Mounjaro can cause serious side effects. In addition to gastrointestinal symptoms such as nausea and severe discomfort, the drug has been linked to gallstones and pancreatitis. Doctors stress that the medication should only be used under proper medical supervision and that people who do not medically need to lose weight should not use it simply to become thinner.
A woman in her 20s who received Mounjaro from a cosmetic clinic in April described suffering severe side effects after her first injection.
She said she had tried various dieting methods without success and became interested in Mounjaro after seeing information online. However, about four hours after receiving the injection, she began experiencing intense chills.
According to the woman, the shivering continued for roughly three days, leaving her unable to concentrate at work and forcing her to spend much of her time wrapped in blankets. Unable to tolerate the side effects, she stopped treatment after a single injection.
Reflecting on the experience, she said her desire to lose weight had been strong, but the adverse reactions convinced her that she needed to pursue healthier methods instead.
Despite such risks, illegal resale remains widespread on social media.
During the investigation, a reporter contacted an account believed to be reselling Mounjaro. The seller confirmed that the drug was available and offered injections for 10,000 yen each. When asked where the medication had been obtained, the seller claimed it had been purchased from a clinic while undergoing cosmetic laser facial treatments.
The seller later sent a video appearing to show the product.
Another account claimed to be a diabetes patient who had accumulated excess supplies due to missed injections and offered to sell them for 7,500 yen each.
Authorities noted that this price was approximately five times higher than the cost of obtaining the drug through insured medical treatment.
When reporters asked whether the sellers understood that reselling prescription medication was illegal, communication ceased. One account subsequently blocked further contact.
Experts warn that purchasing resold medication carries additional dangers. In some cases, products may be counterfeit or contain unknown substances. Buyers also lose the protections normally available through the healthcare system.
Japan's Adverse Drug Reaction Relief System provides compensation for people harmed by side effects from approved medications used appropriately. However, experts say individuals who use Mounjaro as a weight-loss drug rather than for its approved diabetes indication may not qualify for compensation, leaving them responsible for the consequences of unexpected health problems.
Health ministry officials have repeatedly warned that the safety and effectiveness of Mounjaro for dieting purposes have not been fully established in Japan and that misuse could lead to serious health damage.
The issue remains complicated because physicians have some discretion to prescribe medications outside approved indications, and patients are generally free to choose treatments. Overseas, some countries have approved similar drugs specifically for obesity treatment, making information about weight-loss use readily available online.
Medical experts say aggressive promotion on social media by ordinary users has also contributed to the drug's growing popularity, creating what amounts to informal advertising that is difficult to regulate.
As illegal resale spreads and demand for rapid weight loss continues to grow, doctors are urging consumers to carefully consider the risks before turning to prescription diabetes medications for cosmetic purposes.
Source: MBS
