According to UK government statistics, from 2021-2022, 63.8% of English adults were classed as overweight or obese. This is defined as having a body mass index (BMI) of 25 or over.
Being overweight is a risk factor for many weight-related conditions, such as type 2 diabetes, heart disease, stroke, liver and kidney disease, and some cancers.
It's clear that many people need support with losing weight. This has led to the licensing of Mounjaro (tirzepatide) and Wegovy (semaglutide) as weight-loss medications.
Here, we'll discuss the differences and similarities between these two drugs, giving you the information you need to make an informed choice about your weight loss treatment.
Understanding Weight Loss Medications
What is Mounjaro (Tirzepatide)?
Mounjaro, also known as Tirzepatide, is a medication developed by Eli Lilly and Company. It was originally approved in the UK by The National Institute for Health and Care Excellence for the treatment of adults with type 2 diabetes. At the end of 2023, the drug was also licensed as a weight loss medication for people with a BMI of 30kg/m² or above.
The medication works by activating two receptors: the glucose-dependent insulinotropic polypeptide (GIP) receptor and the glucagon-like peptide-1 (GLP-1) receptor.
In simple terms, the drug has a similar structure to these two natural chemicals found in the body (GLP-1 and GIP). When the drug is injected, it has a similar effect to these chemicals - stabilising blood sugar, increasing metabolism, slowing down stomach emptying, and telling your brain that it's full.
In clinical trials, tirzepatide appears to have significant weight loss benefits, with up to 83% of patients experiencing a 5% body weight reduction or more.
What is Wegovy (Semaglutide)?
Semaglutide, marketed under the brand names Ozempic and Wegovy, belongs to the class of medications known as glucagon-like peptide-1 (GLP) receptor agonists.
It's been used for over 15 years to treat type 2 diabetes by helping to control blood sugar levels. Recently, Wegovy was licensed in the UK for weight management in adults with obesity or who are overweight and have weight-related medical problems. Ozempic is the brand that's licensed for type 2 diabetes treatment, and Wegovy is licensed for weight management.
Semaglutide works in many of the same ways as tirzepatide, including improving blood glucose control, slowing down stomach emptying, and reducing hunger signals.
Comparing Mounjaro and Wegovy*
Active Ingredients: Tirzepatide vs Semaglutide
Tirzepatide and semaglutide are two different active ingredients. As they both belong to the GLP 1 receptor agonist family, they both have a similar structure to this chemical.
However, tirzepatide is also a GIP receptor agonist. This means tirzepatide has a structure that's similar to both GIP and GLP-1, and it's the first and only drug to be structurally similar to both.
As we mentioned earlier, both drugs work by reducing how quickly the stomach empties (known as gastric emptying), making you feel fuller for longer. They also make you feel fuller by affecting the release of hunger hormones that tell the brain you're full. Finally, they also work to stabilise blood sugar by affecting insulin secretion.
Efficacy in Weight Loss
In clinical trials, Mounjaro (Tirzepatide) has led to significant weight loss. Participants treated with the highest dose of Mounjaro for 72 weeks lost an average of 23.6 kg.
Wegovy (Semaglutide) taken at the highest dose of 2.4mg has led to a 14.9%-17.4% reduction in body weight. Those on the higher dose experienced an average weight loss of 15.3kg over 68 weeks.
Of those on the highest dose of Mounjaro (15mg), 56.7% lost 20% or more of their body weight. However, only 30% of those on the highest dose of Wegovy lost 20% or more of their body weight.
There's not been a single trial where people were given Mounjaro or Wegovy and the results compared. However, there has been a review that compares individual studies on each drug. This review found that Mounjaro is more effective at supporting weight loss than Wegovy, but further evidence is needed to confirm this.
Safety and Side Effects
Common Adverse Events
The most common side effects for both Wegovy and Mounjaro include gastrointestinal symptoms like indigestion, nausea, vomiting, constipation, diarrhoea, vomiting, constipation, and stomach/abdominal pain. These side effects can be quite mild and usually improve with time as the body adjusts to the medication.
In clinical trials, between 3-7% of enrolled patients receiving Mounjaro had to stop taking it due to these types of side effects. For those taking Wegovy, between 3.4-4.5% of people in a multi-step trial complained of gastrointestinal adverse events.
So far, no study directly compares how often people experience side effects when taking each medication.
Long-term Health Risks
Mounjaro and Wegovy carry a warning for the potential risk of thyroid tumours, including cancers. Other rare side effects include pancreatitis, low blood sugar, gallbladder issues, and kidney problems.
As with all medications, people can rarely suffer from an allergic reaction, which is a medical emergency. Whilst this is more likely to happen after the first use, an allergy may develop after some time. Seek medical help if you're worried about allergic reactions - if you notice facial swelling or your breathing is affected, call 999.
Injection site reactions can occur due to the medication itself. You may notice itching, burning, swelling, or redness, but these types of reactions only usually last a few days.
You should discuss the potential risks and benefits of these medications with your healthcare provider before initiating treatment. Pre-existing health conditions may put you at an increased risk of developing side effects.
Long-term studies are needed to confirm the sustained health risks associated with both tirzepatide and semaglutide.
Usage and Administration
Dosage and Administration Guidelines
Mounjaro (tirzepatide) is available in six different dose strengths ( 2.5 mg, 5 mg, 7.5 mg, 10 mg, 12.5 mg, and 15 mg) and is administered via injection. Wegovy is also given via injection and comes in five different dose strengths (0.25 mg, 0.5 mg, 1 mg, 1.7 mg, and 2.4 mg).
Both medications are given as a subcutaneous injection (under the skin), usually using an injection pen. The best locations to inject are where there is some fat underneath the skin, such as the stomach, front of thighs, or bottom of the upper arm.
With both medications, patients are usually started on the lowest dose and then follow a dose escalation period. They'll continue on this dose for 4 weeks before increasing to the next dose up. This will be repeated until they reach the highest dose. If someone experiences side effects, they may be kept at the current dose for a longer time to help them adjust.
The aim of both medications is to reach the maximum dose, as this is most effective at supporting weight loss.
Lifestyle and Dietary Considerations
Eating a balanced, reduced-calorie diet and nutrient-dense is the best way to support your weight loss journey along with the medications.
Not only will this help the weight loss medications work most effectively, but it will also help you in the future when trying to stop the medications. Research has shown that combining lifestyle modifications with high-protein and very low-calorie diets can increase short-term weight loss to 12–20%.
But it's not just good for weight loss. A healthy lifestyle, including regular exercise, can also reduce your risk of cardiovascular disease. A long-term, sustainable approach to weight management, including a balanced diet, healthier lifestyle, and regular physical activity, is best.
Patient Considerations
Suitability for Different Patient Populations
Mounjaro and Wegovy are both effective weight-loss medications, but that doesn't mean they're suitable for everyone. An individual's medical history, current health status, and the other medications they take may make it unsafe for them to take these medicines.
Mounjaro should not be used in people with the following conditions:
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Certain cancers such as medullary thyroid carcinoma (MTC) or multiple endocrine neoplasia (MEN)
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A history of pancreatitis
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Individuals with type 1 diabetes
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Conditions that affect stomach emptying (gastroparesis)
There's also limited information about the safety of Mounjaro in children and pregnant/breastfeeding women. Women taking oral contraceptives may need to switch to a different method whilst taking Mounjaro, as it may affect how well contraceptives work.
Wegovy should also be avoided in patients with a history of thyroid cancer, gastroparesis, pancreatitis, and if pregnant or breastfeeding. It should also be avoided in people with severe liver/kidney problems.
Patients with type 2 diabetes may be able to take Mounjaro or Wegovy depending on the other medications they're taking. Those with high blood pressure or high cholesterol can take either medication, and are likely to see improvements in these measurements.
Doctor and Healthcare Team Consultation
It's important to consult with a medical professional before taking any weight loss medication. A healthcare professional will be able to review your medical history and medications to make sure any weight loss medication is suitable for you. If you're experiencing any side effects or issues long-term, it's also important to discuss these.
At Quick Meds, we offer online weight loss consultations with a prescriber. After discussing your individual requirements, our staff can prescribe the most appropriate weight loss medication for you. We'll take your preferences into account as much as possible.
Buying your weight loss medication from a reliable source is essential. We previously highlighted the dangers of buying fake weight loss medication online - you can read the article here.
When buying your weight loss medication from Quick Meds, you're buying from a General Pharmaceutical Council-registered, UK-based pharmacy. Medication is delivered quickly, safely, and discreetly to your door.
Conclusion
Both Mounjaro and Wegovy are effective weight loss medications when used along with diet and lifestyle interventions. However, Mounjaro may increase the chances of losing more weight.
Both medications have similar side effects, but may not be suitable for everyone. Make sure to discuss your individual health needs with a health professional before taking any weight loss medication.
FAQs
Is Mounjaro available in the UK?
Yes, since authorisation at the end of 2023, Mounjaro has been available in the UK as a weight loss drug, on prescription.
It's licensed for use in individuals with a body mass index (BMI) of 30kg/m² or more, or a BMI between 27-30kg/m² with weight-related health problems like high blood pressure, high cholesterol, or heart problems.
Can you switch from Wegovy to Mounjaro?
If you're not getting on with one of the drugs, it may be possible to switch to another. However, it's important to go through the risks and benefits of this with a healthcare professional.
Are you looking to switch now? Book an online weight loss consultation with the Quick Meds team today.
Do you gain weight back after stopping Mounjaro?
When individuals stop taking Mounjaro, they may experience weight regain. Research indicates that patients who stopped taking tirzepatide after one year regained about 14% of the weight they lost.
This is probably due to the medication's effects on appetite and feelings of fullness. Once the medication is stopped, appetite may increase, potentially leading to eating more calories.
It's important to create a healthy diet and exercise routine when taking the medication, as this will make it easier to maintain after stopping. Try to manage stress, ensure an adequate sleep routine, and maintain a regular exercise regimen to support weight management after discontinuing Mounjaro.
Is Ozempic the same as Wegovy?
Ozempic and Wegovy contain the same active ingredient, semaglutide, but they are licensed to be used by separate groups of people. Ozempic is used to treat type 2 diabetes, while Wegovy is used for chronic weight management and is prescribed solely as a weight-loss medication.
Although these two medications contain the same active ingredient, they are officially licensed for different uses.
Is Wegovy or Mounjaro more effective in helping lose weight?
There hasn't been a clinical trial that directly compares Wegovy with Mounjaro, but there is a review that summarises the clinical trials of each drug individually. This review found that if both drugs were used at the highest dose, patients taking Mounjaro experienced more significant weight loss.
It's important to note that the patients in these studies all had type 2 diabetes, so the findings may not apply to people without diabetes.