"This level of drop off is concerning because these medications aren't meant to be a temporary quick fix," explained lead author Professor Reimar W. Thomsen from the Department of Clinical Epidemiology, Aarhus University and Aarhus University Hospital, Aarhus, Denmark. "For them to work effectively, they need to be taken long term. All of the beneficial effects on appetite control are lost if the medication is stopped."

Originally developed for diabetes, GLP-1RAs have shown promise in promoting weight loss by reducing appetite and increasing satiety signals from the gut to the brain. However, GLP-1RAs are expensive and can potentially widen health disparities as obesity disproportionally affects marginalised racial, ethnic, and socioeconomic communities.

Moreover, weight regain is common once the medication is discontinued, indicating that people may need to remain on these drugs to keep off the pounds. However, there are growing concerns that many people may stop anti-obesity medications not long after starting them, but population-based data remain scarce.

To provide more evidence, researchers used data from nationwide health registries to examine the likelihood of, and reasons for, discontinuation of semaglutide use for weight loss in all adults (aged 18 or older) without diabetes who initiated treatment between the drug's launch date in Denmark (December 1^st, 2022) and October 1^st, 2023.

Out of 77,310 first time users of semaglutide for weight loss identified, over half (40,262; median age 50 years, 72% women) were no longer taking it after one year -- with 18%, 31% and 42% stopping treatment within 3, 6 and 9 months, respectively. So why do so many people discontinue the drug?

High costs

The analysis found that the most common factor influencing the likelihood of discontinuation was age, with younger users aged 18-29 years 48% more likely to stop treatment within the first year than those aged 45-59 years, after controlling for sex differences. Similarly, users living in low-income areas were 14% more likely to discontinue treatment within the first year than those living in high-income areas.

Both of these factors highlight the likely impact of high costs of these medications (2000 Euros per year for the lowest dose of semaglutide as of June 2025), which is an important barrier to treatment for many people.

Higher predisposition to adverse effects

Additionally, people who had previously used gastrointestinal medications -- which may indicate they are more vulnerable to the common adverse gastrointestinal side-effects reported by GLP1-RA users, such as nausea, vomiting, diarrhea -- were 9% more likely to discontinue semaglutide within the first year.

Similarly, people with a history of psychiatric medications were 12% more likely to discontinue treatment within the first year, while those living with cardiovascular disease or other chronic conditions were around 10% more likely to stop treatment early -- also suggesting a higher likelihood of experiencing adverse effects. "This is particularly concerning given that people with obesity-related comorbidities may reap the greatest benefit from treatment," said Professor Thomsen.

The study also found that men were 12% more likely to stop treatment within a year than women, which might reflect unsatisfactory weight loss given the better weight loss outcomes generally observed in women taking GLP-1RAs than men.

"These results are new and shed light on the reasons for high rates of early discontinuation of semaglutide for weight loss in a real-world setting," said Professor Thomsen. "With over half of adults in Europe living with overweight or obesity, understanding who may benefit most from interventions that encourage adherence is essential to improving treatment use and subsequent health outcomes and quality of life."

Despite the important findings, the authors acknowledge serval limitations of the study, including that anthropometric measures such as the exact BMI are not generally available in Danish health registries, and they could not assess individual-level income, insurance coverage, or out-of-pocket pay, which could partially affect the conclusions. They also note that milder side effects such as gastrointestinal complaints and other potential reasons for discontinuation cannot be captured fully in registries and were likely underestimated. Finally, the researchers did not have information on the amount of weight loss achieved after semaglutide initiation.