What's the difference between Mounjaro, Wegovy and Ozempic?

Dr Babak Ashrafi

Medically reviewed by

Dr Babak Ashrafi

Last reviewed: 06 Mar 2024

Mounjaro, Wegovy, and Ozempic are all injectable medications that contain a glucagon-like peptide 1 (GLP-1) receptor agonist. This type of medication can treat obesity and manage blood sugar levels. Mounjaro is also a dual agonist, which means it mimics another hormone as well as GLP-1.

Mounjaro and Wegovy are weight loss injections that mimic hormones which send signals to the parts of your brain responsible for appetite and hunger. Ozempic helps type 2 diabetics regulate their blood sugar. Below we compare Mounjaro vs Wegovy vs Ozempic to find the main differences between each treatment and which one may be the right option for you.

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Mounjaro vs Wegovy: Key differences to know

Mounjaro and Wegovy are both injections for weight loss that have been approved and licensed in the UK. Wegovy has been available for a while and Mounjaro is a new weight loss injection. The criteria for getting a prescription for Mounjaro or Wegovy is based on your medical history, current medications, and body mass index (BMI). You can get a prescription for either weight loss treatment if you have a BMI of:

  • 30 kg/m2 or more (obese)
  • 27 kg/m2 or more (overweight) and you also have a weight-related medical condition, such as prediabetes or high blood pressure (hypertension)

You can buy Mounjaro and Wegovy online with a prescription through trusted and regulated sellers such as ASDA Online Doctor.

from £169.00

from £179.00

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Mounjaro vs Wegovy: Active ingredients and how they work

Mounjaro contains tirzepatide, while Wegovy contains semaglutide. Both of these are GLP-1 receptor agonists. But Mounjaro is a dual agonist, which means it mimics 2 hormones (glucose‐dependent insulinotropic polypeptide (GIP) and GLP-1).

GLP-1 is usually released after you eat and:

  • sends a signal to your brain that you’re full
  • slows down the emptying of your stomach
  • reduces your blood sugar levels by improving how your body produces insulin (which is why the medication is also used for type 2 diabetes)

Semaglutide and tirzepatide mimic these actions, tricking your brain into thinking that you’re full. As they also delay the emptying of your stomach, this adds to feelings of fullness. By taking Mounjaro or Wegovy, you can reduce your calorie intake and stick to a diet plan more easily without feeling hungry between meals or getting cravings.

Mounjaro mimics 2 hormones although researchers aren’t sure of the full extent of what GIP does. It’s thought to have similar effects to GLP-1 as well as increase its effects, which can enhance weight loss results.

Mounjaro vs Wegovy: Dosages

Mounjaro and Wegovy contain different active ingredients, which means their dosage schedule is different. Whether you take Wegovy or Mounjaro, they must be taken once a week, at the same time and day.

The main difference is that:

  • Mounjaro (tirzepatide) dosage starts at 2.5 mg and can be increased to a maximum dose of 15 mg.
  • Wegovy (semaglutide) dosage starts at 0.25 mg and is increased to a maximum maintenance dose of 2.4 mg.

Both dosage schedules follow a 4-weekly plan. You’ll increase your dose every 4 weeks unless you have severe side effects and your doctor has told you not to.

The Mounjaro dosage schedule is as follows:

Mounjaro weekly dosage guide

The Wegovy dosage schedule is as follows:

Wegovy weekly dose chart to follow for your injections

Mounjaro vs Wegovy: How to use

Both Mounjaro and Wegovy weight loss medication are multi-dose pens. Each pre-filled pen contains 4 doses (so will last 4 weeks) in the exact dosage you’ll need (depending on which week of the dosage schedule you’re on).

Whether you are using Mounjaro or Wegovy, you should always follow the instructions in the patient information leaflet and any other instructions your doctor has given you.

To use Mounjaro or Wegovy:

  1. Always check the dosage and medication are correct and in date before using.
  2. Choose and clean your injection site. You can use the thighs, abdomen, or upper arms. Only inject into your skin, never into a muscle or vein.
  3. Use a new needle for each injection, checking for any signs of damage. If it’s unsealed or damaged in any way, use another needle.
  4. Keep a sharps bin nearby so you can safely dispose of your needle afterwards.
  5. Check that the liquid inside the pen is clear and colourless, or in the case of Mounjaro, it can also have a slightly yellow tinge. If the liquid inside the pen has frozen or looks cloudy, do not use it and speak to your doctor or prescriber.
  6. You may need to prime your pen or check the flow if you’ve not used it before. This makes sure the pen is working as it should.
  7. Follow the injecting instructions for each pen carefully.
  8. Remove the needle and dispose of it, replacing the pen cap and storing it following the manufacturer's instructions.
  9. Make a note of your current dose, date, and time, so you can keep track and follow the dosage schedule accurately.

Mounjaro vs Wegovy: Effectiveness

Several Mounjaro studies have been carried out, with the most important for weight loss being SURMOUNT-1. This clinical trial studied the weight loss effects of tirzepatide (Mounjaro) in non-diabetic patients over 72 weeks. The results found that people lost up to 22.5% of their body weight while taking the highest maintenance dose of 15 mg. The same Mounjaro study found that more than 89% of people lost at least 5% of their starting weight.

STEP-1, a 68-week clinical trial carried out to study the weight loss effects of semaglutide (Wegovy), found that people lost up to 15% of their body weight after taking the 2.4 mg maintenance dose. The same Wegovy study also found that up to 85% of patients lost at least 5% of their starting weight.

Both of these studies have similar results, making both medications effective for weight loss. Which one is best for you will depend on a number of factors, such as which is more suitable, which works better for you, or which one you’d prefer to try.

For Mounjaro and Wegovy to be most effective, you need to follow a diet and exercise program. This will help make sure you get the most from your medication and will help you to maintain a healthy weight, even when you stop taking weight loss treatment.

Mounjaro vs Wegovy: Costs

The cost of each Mounjaro or Wegovy pen equals 4 weeks of treatment. The prices for both are similar. Below is a comparison table with the cost for each dose if you wanted to get weight loss treatment through ASDA Online Doctor:

Mounjaro (tirzepatide) Wegovy (semaglutide)
Lowest dose

2.5 mg = £184

0.25 mg = £169

Second dose

5 mg = £184

0.5 mg = £169

Third dose

7.5 mg = £189

1.0 mg = £169

Fourth dose

10 mg = £189

1.7 mg = £224 

Fifth dose

12.5 mg = £204


Highest dose

15 mg = £204

2.4 mg = £269

Mounjaro vs Wegovy: Side effects

When comparing Wegovy vs Mounjaro for weight loss, side effects are similar because they mimic the same hormone. The main difference is that the same side effects may be listed as common for Mounjaro but very common for Wegovy, and so on.

Below we compare the different side effects for each medication, with similarities in bold.

Very common side effects of Mounjaro and Wegovy:

Mounjaro Wegovy
  • nausea (feeling sick)
  • diarrhoea
  • vomiting (being sick)
  • constipation
  • nausea
  • diarrhoea
  • vomiting
  • constipation
  • headache
  • stomach pain
  • feeling weak or tired

Common side effects of Mounjaro and Wegovy:

Mounjaro Wegovy
  • dizziness
  • stomach pain (indigestion, bloating, burping, gas) 
  • reflux or heartburn 
  • hair loss 
  • injection site reactions (itching or redness) 
  • allergic reaction (rash, itching, eczema) 
  • low blood pressure (hypotension)
  • feeling tired (fatigue)
  • dizziness
  • stomach pain (indigestion, bloating, burping, gas) 
  • reflux or heartburn
  • hair loss
  • injection site reactions (itching or redness)
  • inflamed stomach (gastritis)
  • gallstones

Most side effects for Mounjaro and Wegovy are not usually severe and will go away over time. They are most common when you first start using the medication, or after a dose increase. If you do get side effects from either medication and they are mild, treat them at home. If side effects become severe or do not go away, speak to your doctor.

Uncommon side effects of Mounjaro and Wegovy:

Mounjaro Wegovy
  • fast pulse/heartbeat
  • an increased levels of pancreatic enzymes (such as lipase and amylase)
  • gallstones
  • injection site pain
  • an increased level of calcitonin in the blood (a hormone that makes and regulates calcium levels in your blood)
  • cholecystitis (an infection of the gallbladder)
  • fast pulse/heartbeat
  • an increased levels of pancreatic enzymes (such as lipase and amylase)
  • stomach paralysis

Serious side effects of Mounjaro and Wegovy:

Mounjaro Wegovy
  • uncommon: an inflamed pancreas (acute pancreatitis)
  • rare: a serious allergic reaction (anaphylaxis)
  • common: complications of a diabetic eye disease called diabetic retinopathy (only in diabetics)
  • uncommon: an inflamed pancreas (acute pancreatitis)
  • rare: a serious allergic reaction (anaphylaxis)

For the most up-to-date Mounjaro or Wegovy side effects, check your patient information leaflet.

Mounjaro vs Ozempic

Mounjaro is a weight loss medication and type 2 diabetes treatment. Ozempic is a type 2 diabetes treatment only, although it’s been gaining attention online as it contains semaglutide (the same as Wegovy).

Mounjaro vs Ozempic: Differences

The main differences between Mounjaro and Ozempic are:

  • Mounjaro is approved for weight loss in the UK but Ozempic is only approved for type 2 diabetes.
  • Mounjaro contains tirzepatide and Ozempic contains semaglutide.
  • You cannot get a prescription for Ozempic for weight loss*, but you can get a prescription for Mounjaro for weight loss.
  • Mounjaro is used to reduce your appetite, delay the emptying of your stomach and help you feel fuller while following a diet plan. Ozempic is used to regulate blood sugar levels by improving how your body uses insulin.
  • Ozempic is made for diabetes so the dosage schedule isn’t as effective for weight loss, with a maximum dosage of 2 mg. Mounjaro follows a weight loss dosage schedule, with a maximum dosage of 15 mg.
  • Side effects are similar as they both contain a medication from the same drug group, but Ozempic side effects are targeted towards those with type 2 diabetes.

* You may be able to get Ozempic prescribed off-label, but the price could be higher as it isn’t approved for this purpose. You may also find it difficult to find a doctor willing to do this. ASDA Online Doctor doesn't recommend getting a type 2 diabetes medication prescribed off-label. This causes shortages and there are plenty of approved and more effective weight loss treatments.

Mounjaro vs Ozempic: Similarities

The main similarities between Mounjaro and Ozempic are:

  • They can both treat type 2 diabetes.
  • They are injectable pens that are taken in a similar way.
  • They both contain a GLP-1 receptor agonist.
  • You should follow a diet and exercise plan while taking them.

Wegovy vs Ozempic

Wegovy and Ozempic contain the same active ingredient (semaglutide), so many people think that Ozempic is a Wegovy alternative. The difference between Wegovy and Ozempic is that Wegovy is approved for weight loss while Ozempic is only approved for managing blood sugar levels if you have type 2 diabetes. They work in the same way but have different dosage schedules.

Both Wegovy and Ozempic come as an injectable pen that contains 4 doses. Wegovy is effective for weight loss and has been proven so in clinical trials, while Ozempic has not been tested specifically for this purpose, although it may help type 2 diabetics lose some weight.

Wegovy and Ozempic side effects are similar, but whether they are very common, common, or uncommon depends on the medication. This is because the doses for Wegovy are higher and they are used for different purposes.

When comparing Ozempic vs Wegovy cost, this is often similar (around £169 for the starting dose) but it may be more difficult to get hold of Ozempic for weight loss.

Mounjaro vs Wegovy vs Ozempic

If you want to find all the differences and similarities between Mounjaro, Wegovy, and Ozempic quickly, the table below includes all the key information for each treatment:

Comparison table of Mounjaro vs Wegovy vs Ozempic

Frequently asked questions

Is Wegovy or Mounjaro more effective?

Both Wegovy and Mounjaro are effective for weight loss. Results from clinical studies have shown that people can lose up to 22.5% of their weight with Mounjaro, and up to 15% of their weight with Wegovy. As the active ingredients are slightly different, you may find that one treatment is better for you or that one causes fewer side effects.

Can I switch from Wegovy to Mounjaro?

Yes, you can switch from Wegovy to Mounjaro but you must wait at least 5 weeks between. This gives enough time for any remaining medication from Wegovy to leave your system, so you can start Mounjaro safely. No matter what Wegovy dose you were taking, you’ll start on the lowest dose of Mounjaro and follow the dosing schedule. Speak to a doctor if you want to switch from Wegovy to Mounjaro, as they can help you do so safely.

Is Wegovy or Mounjaro more expensive?

Wegovy and Mounjaro are a similar price, although the starting dose of Wegovy (£169) is slightly less than Mounjaro (£184). This evens out as you move up to the maintenance dose, as the Wegovy maintenance dose price (£269) is slightly higher than Mounjaro’s maintenance dose price (£189 to £204, depending on whether you take 10 mg, 12.5 mg or 15 mg).

Is semaglutide or tirzepatide better for weight loss?

Both semaglutide and tirzepatide work well for weight loss. Semaglutide (Wegovy) and tirzepatide (Mounjaro) have been proven to help people lose weight and are most effective when taken alongside a diet and exercise plan.

Medically reviewed by:
Dr Babak Ashrafi Clinical Lead for Service Expansion

Babak studied medicine at King’s College London and graduated in 2003, having also gained a bachelor’s degree in Physiology during his time there. He completed his general practice (GP) training in East London, where he worked for a number of years as a partner at a large inner-city GP practice. He completed the Royal College of GPs membership exam in 2007.

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Last reviewed: 06 Mar 2024

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