The difference between dulaglutide and semaglutide, explained clearly

How the two medicines differ in mechanism and licensed use

Both dulaglutide and semaglutide activate GLP-1 receptors, which are involved in appetite regulation, blood sugar control and slowing how quickly the stomach empties. At that level they share a pharmacological family. The meaningful difference lies in what each medicine is actually authorised to do in the UK.

Semaglutide is licensed under the brand name Wegovy specifically for weight management in adults with a BMI of 30 or above, or 27 or above alongside a weight-related health condition. The NHS medicines page for semaglutide sets out its approved uses and side-effect profile clearly. Dulaglutide, sold as Trulicity, is licensed by the MHRA for type 2 diabetes, not for weight management. That distinction shapes everything that follows: the doses studied, the populations enrolled in trials, and the outcomes measured.

It is also worth separating semaglutide from Ozempic, which is the same molecule but licensed only for type 2 diabetes. The difference between Wegovy and Ozempic is one of licence and dose, not chemistry, a distinction that often confuses people researching this area.

What the clinical evidence shows about weight outcomes

The STEP 1 trial, published in the New England Journal of Medicine, enrolled 1,961 adults with obesity and no diabetes over 68 weeks. Participants taking semaglutide 2.4mg weekly lost an average of around 15% of their body weight, compared with roughly 2.4% on placebo alongside lifestyle support. That is the foundational evidence underpinning Wegovy's weight-management licence.

Dulaglutide's trial programme was designed around glycaemic control, not weight loss. Average weight reductions reported in its diabetes trials were considerably more modest (typically in the range of 1–4 kg) and those participants were not necessarily selected on the basis of obesity. Comparing these figures directly is problematic: different populations, different endpoints, different follow-up periods. If you want a fuller picture of where each medicine sits, our page comparing dulaglutide and semaglutide works through the evidence in more detail. The honest read is that no robust head-to-head trial has tested dulaglutide against semaglutide in a weight-management population, so any number-to-number comparison should be treated with caution.

If you are researching how semaglutide compares with another GLP-1, our page on the difference between liraglutide and semaglutide covers a more commonly drawn comparison in the weight-loss context.

Side effects, dosing and practical differences

Both medicines carry a broadly similar gastrointestinal side-effect profile: nausea, diarrhoea, constipation and vomiting are the most commonly reported, tending to be most noticeable at the start of treatment or after a dose increase, and often settling over days to weeks. The NHS semaglutide page lists the full profile for Wegovy specifically.

Dosing structures differ. Semaglutide for weight management is titrated from 0.25mg weekly upward through several steps to a 2.4mg maintenance dose, with a newer 7.2mg option now MHRA-approved for eligible adults. Dulaglutide is given at diabetes-appropriate doses (0.75mg or 1.5mg weekly, sometimes up to 3mg or 4.5mg in later prescribing). These are not interchangeable schedules, and neither medicine's dose should ever be self-adjusted. If questions about missed doses or titration timing come up, the Patient Information Leaflet and your prescriber are the right place to resolve them.

Storage requirements are similar: both are refrigerated, subcutaneous, once-weekly injections. Neither is a tablet. If an oral option is something you are weighing up, Wegovy's treatment page covers the recently approved oral semaglutide formulation alongside the injection.

A plain summary of the key differences

Semaglutide is the medicine with the evidence base and the regulatory authorisation for weight management in the UK. Dulaglutide is not. That is the clearest way to state what the difference between dulaglutide and semaglutide means in practice for someone exploring weight-loss treatment. People sometimes extend this question further to ask about newer agents, and our page on the difference between retatrutide and semaglutide is worth reading if you are curious about how the next generation of GLP-1 medicines compares. If you would like to understand how semaglutide sits alongside other agents in the GLP-1 class, the page on what distinguishes GLP-1 medicines from semaglutide specifically goes into more depth.

If you are currently taking dulaglutide for diabetes and wondering about weight management options, that is exactly the kind of clinical picture our prescribers work through with patients. A transfer or co-prescribing question like that deserves a real conversation, not a webpage. Speak to our prescribers through a free consultation, and they will review the full picture with you.