If you’ve looked into weight loss injections even briefly, you’ve probably noticed something odd.
Everyone seems to be talking about the same three names, but nobody seems to agree on what they actually mean.
Some say Wegovy and Ozempic are the same thing.
Others say Mounjaro is “basically Wegovy but stronger”.
And somewhere in between, people are switching medications without really knowing why.
It’s not surprising. These treatments sound similar; they’re all injections, and they’re often discussed in the same breath.
But medically speaking, they are not interchangeable, and choosing between them based on hearsay can lead to disappointment, side effects, or unrealistic expectations.
This article breaks down the real differences between Wegovy, Ozempic, and Mounjaro, using clinical evidence and the UK prescribing context, so you can understand how they work, how much weight people typically lose, and who each medication is actually for.
What is Wegovy?
Wegovy is a prescription-only injection licensed specifically for long-term weight management.
Its active ingredient is semaglutide, a medication that mimics the hormone GLP-1 (glucagon-like peptide-1). This hormone plays a key role in regulating appetite, satiety, and food intake.
In the UK, Wegovy is approved for adults who:
- Have a BMI of 30 or higher, or
- Have a BMI of 27 or higher with at least one weight-related condition, such as high blood pressure or type 2 diabetes
Wegovy is taken once weekly using a pre-filled pen. The dose starts low and is gradually increased over several months until the maintenance dose of 2.4 mg is reached.
That dose matters. Wegovy is designed to deliver stronger appetite suppression than semaglutide products used for diabetes, which is why it is licensed specifically for obesity treatment.
Wegovy is intended for long-term use, alongside dietary changes and physical activity, rather than short-term or cosmetic weight loss.
What is Ozempic?
Ozempic also contains semaglutide, which is where much of the confusion begins.
However, Ozempic is licensed to treat type 2 diabetes, not obesity.
Weight loss with Ozempic is considered a secondary effect, resulting from improved appetite control and blood sugar regulation. It is not the primary treatment goal.
Key differences between Ozempic and Wegovy include:
- A lower maximum dose
- Different prescribing guidelines
- A primary focus on glycaemic control, not weight management
Ozempic is typically prescribed at doses up to 1 mg or 2 mg, depending on the formulation. These doses can support modest weight loss, but they do not usually produce the same results seen with Wegovy’s 2.4 mg dose.
Despite sharing the same active ingredient, Wegovy and Ozempic are not the same medication in clinical practice.
What is Mounjaro?
Mounjaro takes a different approach.
Its active ingredient, tirzepatide, works on two hormonal pathways, rather than one.
Mounjaro activates:
- GLP-1 receptors, like Wegovy and Ozempic
- GIP (glucose-dependent insulinotropic polypeptide) receptors, which further influence insulin sensitivity and appetite
This dual mechanism helps explain why Mounjaro often leads to stronger appetite suppression and greater average weight loss.
In the UK, Mounjaro is currently approved for type 2 diabetes. It is increasingly prescribed privately for weight loss while broader NICE guidance continues to develop.
Like the other treatments, Mounjaro is taken once weekly, with gradual dose escalation to improve tolerability.
How do Wegovy, Ozempic, and Mounjaro work differently?
All three medications influence appetite, but the biology behind them is not identical.
Wegovy and Ozempic
- Activate GLP-1 receptors
- Slow gastric emptying
- Increase feelings of fullness
- Reduce hunger between meals
- Lower calorie intake indirectly
GLP-1 is released naturally after eating. By enhancing its effect, these drugs help regulate appetite in a way that feels more automatic than traditional dieting.
Mounjaro
- Activates GLP-1 receptors
- Activates GIP receptors
- Improves insulin sensitivity more strongly
- Produces deeper appetite suppression
The addition of GIP appears to amplify metabolic effects, which contribute to the stronger results seen in clinical trials. However, stronger effects can also mean stronger side effects for some people.
Which leads to more weight loss?
Clinical trials provide clear differences in average weight loss between Wegovy, Ozempic, and Mounjaro.
Wegovy vs Ozempic vs Mounjaro: Weight Loss Results Compared
| Medication | Active ingredient | Primary approval | Average weight loss | Type 2 diabetes/weight loss |
|---|---|---|---|---|
| Wegovy | Semaglutide | Weight management | 15–20% | STEP trials |
| Ozempic | Semaglutide | Type 2 diabetes | 5–10% (off-label) | Diabetes studies |
| Mounjaro | Tirzepatide | Type 2 diabetes/ weight loss | up to 26.6% | SURMOUNT trials |
Mounjaro generally produces the largest average weight loss, followed by Wegovy. Ozempic typically results in more modest weight loss, reflecting its lower dose ceiling and different treatment goal.
Results vary significantly between individuals, and a higher average loss does not guarantee a better experience for everyone.
Side effects and tolerability
All three medications share similar side effects because they act on the digestive system. Common side effects include:
- Nausea
- Diarrhoea
- Constipation
- Fatigue
- Reduced appetite to the point of discomfort
Wegovy and Ozempic tend to be more predictable in how people tolerate them, largely due to their single-hormone mechanism.
Mounjaro’s dual action can produce more pronounced effects, which some people tolerate well and others find challenging, particularly during dose increases.
Side effects are most common during the early weeks of treatment and/or when the dose is increased too quickly.
Gradual titration improves tolerability for most patients.
Titration is the process of gradually increasing the dosage over several weeks or months.
Which option is safer?
None of these medications is universally “safer” than the others. Safety depends on the following (but not limited to):
- Medical history
- Existing health conditions
- Medication interactions
- Dose escalation speed
- Ongoing monitoring
All three are:
- Prescription-only
- Supported by large clinical trials
- Intended for long-term, supervised use
People with certain conditions, such as a history of pancreatitis or specific endocrine disorders, may not be suitable candidates for any of them.
A clinical assessment is always required.
Which one should you choose?
Choosing between Wegovy, Ozempic, and Mounjaro is not about trends or social media recommendations. It’s about fit.
Wegovy may be suitable if
- Weight loss is your primary goal
- You meet the BMI eligibility criteria
- You want a treatment licensed for obesity
- You prefer a well-established GLP-1 option
Ozempic may be suitable if
- You have type 2 diabetes
- Blood sugar control is the main priority
- Weight loss is a secondary benefit
Mounjaro may be suitable if
- You have not responded well to GLP-1 alone
- Stronger appetite suppression is required
- You are accessing treatment privately
- You can tolerate more intense effects
A healthcare professional should always guide this decision. If you need assistance with your decision, check out our weight loss programme to consult with a certified weightloss prescriber.
Frequently asked questions
Is Wegovy the same as Ozempic?
No. They contain the same active ingredient but are licensed, dosed, and prescribed differently.
Is Mounjaro better than Wegovy for weight loss?
On average, Mounjaro leads to greater weight loss, but it may also cause stronger side effects and is not suitable for everyone.
Can you switch from Ozempic to Wegovy?
Yes. Switching is possible under medical supervision, especially when weight loss becomes the primary treatment goal. But before switching, please consult with your prescriber or GP.
Which is best for people without diabetes?
Wegovy is currently the most appropriate licensed option for non-diabetics seeking weight loss treatment.
Are these injections safe long-term?
Long-term studies support their safety when prescribed appropriately and monitored regularly.