Novo Nordisk A/S expects shortages of Ozempic and Victoza to continue in Europe into 2024 as demand soars for diabetes drugs that can also help with weight loss.

For both medicines, shortages will get worse as the end of this year approaches, according to a letter to healthcare professionals published November 21 by the European Medicines Agency. For Ozempic, intermittent shortages will then probably continue through 2024, while for Victoza, shortages will last until at least the second quarter.

Novo has failed to keep up with demand for Ozempic and its sister drug Wegovy, a weight loss medicine, as celebrity endorsements and social media fame have made them among the world’s most sought-after drugs. In order to boost the supply of Ozempic, Novo said in the letter it has temporarily reduced the supply of Victoza.

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The letter is something that Novo agreed on with EMA to ensure doctors are fully informed, a spokesperson said.

Increased demand for the drugs, coupled with manufacturing constraints, has fueled shortages, including out-of-stock situations, Novo said in the letter. Quality defects or safety issues haven’t been a factor, the company said.

Novo advised in the letter that no new patients be started on Victoza until at least the second quarter of 2024, with current supplies prioritized for existing patients. Novo is also limiting the supply of the 0.25 mg starting dose for Ozempic, suggesting that doctors limit the number of new patients starting on the drug until supply becomes more readily available in the first quarter of next year.