Since early September, Eli Lilly has significantly increased the UK price of Mounjaro (tirzepatide), bringing it closer in line with U.S. and European pricing. While it wasn’t quite the 170% increase some expected, the jump to around £215 per pen represents a major shift for patients who are used to far lower prices.
In contrast, Novo Nordisk has kept UK pricing for Ozempic (semaglutide) relatively stable. So what’s the difference between these two increasingly popular weight loss and diabetes medications?
Ozempic vs. Mounjaro: What’s the Difference?
Ozempic launched in the UK in 2019 as a treatment for type 2 diabetes. It quickly gained traction due to its noticeable weight loss effects. Novo Nordisk then introduced Wegovy, a higher-dose version of semaglutide approved specifically for weight management, and Rybelsus, an oral tablet formulation of semaglutide. All three share the same active ingredient: semaglutide, a GLP-1 receptor agonist.
Mounjaro was approved in the UK in 2023 and uses a newer molecule called tirzepatide. It acts on both GLP-1 and GIP receptors, making it more effective in its metabolic action. This dual mechanism enhances insulin sensitivity, suppresses appetite, and increases fat oxidation. In my experience, Mounjaro often results in more weight loss than Ozempic with fewer side effects.
On average, people using semaglutide (Ozempic or Wegovy) lose about 15% of their body weight over one year. Mounjaro users can see reductions of up to 20% or more, according to the SURMOUNT trials. This makes it particularly attractive to patients aiming for more aggressive results.
Ozempic vs Mounjaro: What’s Safer?
One major point of difference is cardiovascular outcome data. Semaglutide has more established data for reducing the risk of major adverse cardiovascular events (MACE), regardless of weight loss.
Mounjaro shows promise but it’s newer and long-term cardiovascular benefits are still under active investigation. Results from the SURPASS-CVOT trial are expected in 2025. I think it’s highly likely we will learn Mounjaro is as good as Ozempic. Until then, some patients prefer semaglutide given the greater level of experience and data.
Ozempic vs Mounjaro: What Causes More Side Effects?
Side effect profiles for both drugs are similar, most commonly involving nausea, constipation, or diarrhoea, especially during dose escalation. I see patients report fewer side effects with tirzepatide, but this varies.
For all patients, I start with a lower dose and gradually increase it under supervision. Explore our guide to GLP-1 medications and how they support longevity.
Ozempic vs Mounjaro: Maintenance and Microdosing
Many patients build up to a higher dose for weight loss and then transition to a “maintenance dose” to sustain their results. This is commonly referred to as microdosing. Both semaglutide and tirzepatide are used in this way, although it’s an off-label approach.
For those who have reached their target weight, a lower maintenance dose may continue to offer metabolic support without the side effects (and cost!) of full-dose therapy. This strategy can be tailored during follow-ups and monitoring.
Tablet Options: Rybelsus vs Mounjaro vs Ozempic / Wegovy
If injections are a concern, Rybelsus offers an alternative. It delivers semaglutide in tablet form, making it ideal for people who have an aversion to needles. There is no oral formulation of tirzepatide right now.
Patients with GI sensitivity or skin reactions to injectable medications may also find oral GLP-1 agonists more comfortable, though the overall benefit in weight loss may vary. Rybelsus is taken once daily, and timing it correctly in a fasted state is important for optimal absorption.
Ozempic vs Mounjaro: Costs
Currently, Mounjaro is significantly more expensive than Ozempic / Wegovy, which are more widely available and supported by longer-term experience. For many, the price difference becomes a deciding factor, especially if tolerability and weight loss results are similar.
In terms of long-term use, semaglutide is generally seen as safer, simply because it has been studied longer. Some patients starting with tirzepatide eventually switch to semaglutide for maintenance due to comfort with the data, cost, or insurance/availability issues.
In my practice I often help patients carefully switch from one medication to the other and have experience of helping patients do this due to side-effects, supply or cost issues. For a deeper understanding of metabolic health and anti-ageing strategies, explore our Longevity Medicine blog.
What about new alternatives like Retatrutide and Orforglipron?
Retatrutide, a next-generation triple agonist, targets GLP-1, GIP, AND glucagon receptors. It’s shown even better weight loss potential than Mounjaro in early trials — with some patients losing over 24% of their body weight. However, it’s not yet been officially released.
Eli Lilly’s oral GLP-1 receptor agonist, Orforglipron, offers a tablet-based alternative to injections. While promising for convenience, early data suggests weight loss results are more modest compared to injected semaglutide (Ozempic) or tirzepatide (Mounjaro).
Final Thoughts
Both Ozempic and Mounjaro are transformative options for managing metabolic health and supporting longevity. The choice between them should be guided by medical advice, personal goals, side effect profile, and budget.
Whether starting on one or considering a switch, it’s essential to work closely with a doctor experienced in longevity medicine, peptide therapy, and weight optimisation.
