Half of adults without diabetes who begin taking the weight-loss drug semaglutide stop within a year, according to a Danish population-wide study.
The research tracked 77,310 first-time users in Denmark between December 2022 and October 2023.
More than half (40,262; median age 50 years, 72 per cent women) had discontinued after 12 months. At three, six and nine months, 18, 31 and 42 per cent respectively had already stopped.
Lead author Professor Reimar W. Thomsen from the department of clinical epidemiology at Aarhus University, said: “This level of drop off is concerning because these medications aren’t meant to be a temporary quick fix.
“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.”
Semaglutide belongs to a class of drugs called GLP-1 receptor agonists. They reduce appetite and boost satiety signals from the gut to the brain.
First developed for diabetes, they are now widely used for weight loss.
However, they are costly and could widen health inequalities, as obesity disproportionately affects marginalised racial, ethnic and socioeconomic groups.
Weight regain is also common once treatment ends, suggesting many people may need long-term use to maintain results.
There have been concerns that large numbers stop taking anti-obesity drugs soon after starting, but population-based data have been limited until now.
The study found several factors linked to early discontinuation.
Younger users aged 18 to 29 were 48 per cent more likely to stop within the first year compared with those aged 45 to 59.
People in low-income areas were 14 per cent more likely to stop than those in higher-income areas.
Cost was another barrier, with semaglutide priced at about €2,000 per year for the lowest dose as of June 2025.
Users with a history of gastrointestinal medication were nine per cent more likely to stop, possibly due to side effects such as nausea, vomiting and diarrhoea.
Those with a psychiatric medication history were 12 per cent more likely to discontinue, while people with cardiovascular disease or other chronic conditions were around 10 per cent more likely to stop early.
Professor Thomsen said: “This is particularly concerning given that people with obesity-related comorbidities may reap the greatest benefit from treatment.”
The study also found that men were 12 per cent more likely to stop than women, which might reflect less weight loss benefit compared with women, who generally respond better to GLP-1 drugs.
Professor Thomsen said: “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.
“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.”
The researchers noted several limitations, including missing data on BMI, individual-level income, insurance coverage and out-of-pocket costs.
They also said mild side effects and other reasons for discontinuation were likely under-reported.
Data on weight loss achieved after starting semaglutide were not available.