PMDA warns on off-label GLP-1 slimming use

Japan’s Pharmaceuticals and Medical Devices Agency posted PMDA Alert for Proper Use of Drugs No. 18 (October 2026), titled Request for Proper Use of GLP-1 Receptor Agonists and GIP/GLP-1 Receptor Agonists. Mix Online and MEDIFAX report the posting date as October 30, 2026. The English PDF is a convenience translation; PMDA says the Japanese original prevails if the two differ.

What the alert says

PMDA writes that some medical institutions are prescribing these drugs for aesthetic and slimming purposes other than treating type 2 diabetes mellitus and obesity. Japan’s Ministry of Health, Labour and Welfare issued proper-use notifications on June 16, 2026, and October 14, 2026. The agency says safety and efficacy have not been established for off-label aesthetic or slimming use, and it tells clinicians to stick to each product’s electronic package-insert indications and dosing. Patients who develop vomiting or cannot take food or water should stop the drug and seek care, the alert says.

Report counts — not incidence rates

A table of major adverse reactions reported with aesthetic or slimming use draws on Japan’s adverse drug event database for April 2004 to May 2026 (database as of September 2026). Footnotes state the numbers are reports from marketing authorization holders, healthcare institutions and others and do not represent the incidence of adverse reactions:

• Gastrointestinal symptoms: 28 (Mounjaro 19; Rybelsus tablets/Ozempic 8; Victoza 1)
• Ketosis, ketoacidosis or starvation ketoacidosis: 17, all Mounjaro
• Hypoglycemia: 14 (Mounjaro 13; Victoza 1)
• Pancreatitis: 11 (Mounjaro 7; Rybelsus/Ozempic 4)
• Zepbound and Wegovy: 0

Three emergency cases

The alert details three off-label weight-control cases of ketosis or ketoacidosis that led to ambulance transport or emergency care. All three patients were women in their 20s; all recovered. Two obtained the drug online. One (Case 1, ketosis) started at a BMI of about 18, had a history of anorexia nervosa, and needed emergency hospitalization after severe nausea and vomiting. The other two were diagnosed with starvation ketoacidosis after frequent vomiting limited oral intake.

What is not known

• Whether every tabulated report was independently verified beyond the database extract PMDA cites.
• Product identity in each of the three narrative cases (the vignettes do not name a brand; the ketosis column totals are all listed under Mounjaro).
• How many of the 17 ketosis reports overlap with the three vignettes.

What to watch

Any follow-on MHLW or society guidance tied to the June 16 and October 14 notices, and whether later PMDA updates revise the report table.