What is Mounjaro (Tirzepatide)?
Mounjaro® (tirzepatide) is a weekly injection for adults trying to lose weight. It helps people with high BMIs (body mass indexes) lose weight. It contains the active ingredient tirzepatide. Mounjaro® is also known as Zepbound.
If prescribed, it’s important that Mounjaro® is used alongside healthy lifestyle changes, such as more physical activity and a reduced calorie diet.
Who is eligible for Mounjaro?
People who can use Mounjaro® include:
- Adults with a BMI of 30 or above
- Adults with a BMI of 27 or above with weight related health problems, such as a history of heart attack, stroke, or breathing problems during sleep
You shouldn’t use Mounjaro® if you’re allergic to any of the ingredients. Our clinicians will make sure it's safe for you to use, especially if you:
- Have issues with food digestion
- Have ever had pancreatitis
- Have eye problems
- Are using diabetes medication
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What will a clinician consider before prescribing a two-pen (eight week) supply?
You will not be prescribed a two-pen supply until a clinician has confirmed that it is suitable for you. Whether a two-pen supply is suitable for you will depend on factors including:
- Weight
- BMI
- Any weight-related health conditions
- Current treatment and dose
- Treatment history
Your clinician will review how long treatment should continue and which dose remains appropriate for you.
How does Mounjaro work?
Mounjaro works by mimicking the actions of the hormones normally found in the small intestine (GLP-1 and GIP) and, by doing so, causes insulin to release from your pancreas. This has the following effect on your body:
- Suppresses appetite - GLP-1 affects the regulation of appetite
- Regulates blood sugar - Glucagon (the hormone that can raise blood sugar) is blocked, helping you to feel fuller for longer
- Food leaves your stomach slower - Slows down digestion so you may eat smaller portions
Overall this encourages you to eat less overall, which can help kickstart your weight loss journey (though will be helped alongside a healthy diet and regular exercise).
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What receptors does Mounjaro affect?
Weight loss injections like Wegovy or Ozempic are known as GLP-1 agonists. These mimic the naturally occurring GLP-1 (glucagon-like peptide-1) hormone and attaches to its cell receptor to replicate the effects, i.e. effects on blood sugar.
Mounjaro, or to be more specific Tirzepatide (its active ingredient), is a dual receptor agonist. This means it mimics the hormone and affects the receptor for two different hormones – GLP-1 and GIP (glucose-dependent insulinotropic polypeptide). GIP helps to control appetite in the brain.
How effective is Mounjaro for weight loss?
When it comes to weight loss, every person is different. Some people will lose weight faster than others. Mounjaro® can help you lose weight from the first dose alongside a healthy diet and regular exercise.
Clinical trials have shown that on average, patients lost up to 22.5% of their original weight on the highest dose of Mounjaro® (15mg) after 72 weeks. Most adults (91%) can also expect to lose at least 5% of their body weight when using Mounjaro®.
“While being an effective weight loss aid, it is not a miracle drug. It is important that this medication should also be introduced in conjunction with other lifestyle changes, such as a reduced-calorie diet and exercise.” - Dr Mitra Dutt
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How does Mounjaro compare to other weight loss injections?
Mounjaro® weight loss injections are one of several medicated weight loss options currently available via prescription. Others in the market include Wegovy®, and Saxenda®. But what's the difference between Mounjaro®, Wegovy® and Ozempic®?
- All three treatments are weekly injections
- Mounjaro® has the active ingredient tirzepatide. Wegovy® and Ozempic® have the active ingredient semaglutide
- Mounjaro® and Wegovy® are primarily used for weight loss. Ozempic® is primarily used for blood sugar regulation in type-2 diabetes
- All three treatments reduce and regulate appetite
- Clinical trials for Mounjaro® resulted in 91% of people losing more than 5% of their body weight, compared to 84% with Wegovy®. Ozempic® has not been tested as a weight loss drug
“Mounjaro® works in a similar way to other available injectable weight loss products, such as Wegovy® and Saxenda®, however, it is more effective.
Based on clinical trials, 91% of people were able to lose more than 5% of their body fat using Mounjaro®. In similar trials, 84% of people lost more than 5% of their body weight on Wegovy®, and 60% on Saxenda®.” - Dr Mitra Dutt
How to use Mounjaro
Looking at your kwikpen for the first time, you may be wondering “how do I take Mounjaro®?”.
You inject Mounjaro® once a week into your tummy, thigh or upper arm. Read our article or look at our guide below to find out more about how to inject yourself. Please note, alcohol swabs are not provided.
You should inject Mounjaro® on the same day every week. You can take it at any time of day. You might want to set a reminder on your phone, so you don’t forget what day you normally take it.
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How to inject Mounjaro
Follow the steps below on how to use the Mounjaro® kwikpen:
- Wash your hands.
- Inspect your pen. Check the expiry date and that the pen contains the right dose. Check the liquid inside is colourless to a slightly yellow tone. Don’t use the pen is the liquid has been frozen, has particles in it, is discoloured or cloudy. Don’t use the medication if the name or dose doesn’t match your prescription. Or if the pen is expired, damaged or the medication has been frozen.
- Pull off the grey base cap. This should come off easily.
- Wipe the red inner seal with a swab.
- Select a new pen needle. Always use a new needle for each injection. Then pull off the paper tab from the outer needle shield.
- Push the capped pen needle straight onto the pen. Then twist the pen needle until it’s tight.
- Pull off the outer needle cap and keep it. Then pull off the inner needle cap, this can go in the bin.
- Slowly turn the knob dose, you’ll hear 2 clicks, and the extended line will be shown in the dose window.
- Hold your pen with the needle upwards and tap the cartridge holder gently. Then release some medicine into the air by pushing the dose knob until it stops. Slowly count to 5 while you do this. The 0 icon must be shown in the dose window.
- Choose where to inject yourself. Mounjaro® can be injected in your lower stomach, thighs or back of your upper arms. You can use the same area of your body every week but be sure to change your injection site.
- Turn the dose knob until it stops and the icon is shown in the dose window. The icon is equal to a full 0.6ml dose.
- Press the button at the top of the pen down for up to 10 seconds. You’ll hear a click, this means the injection has started. Listen for a second click this means the injection is complete. You can check your dose has been administered by seeing if the grey plunger at the top end of the pen is visible.
- Pull the needle out of your skin, it’s normal to see a drop of medicine on the needle. If you see some blood lightly press the area with cotton wool.
- Check that the icon is in the dose window, if it is then you’ve had the full dose. If you don’t see the icon in the dose window reinsert the needle and finish the injection.
- Replace the outer needle shield.
- Unscrew the capped needle and put it in your sharps bin. Then replace the pen cap.
Mounjaro dosage and schedule
Mounjaro® comes in several doses. Depending on where you are in your treatment journey, you will need to take a different dose.
The starting dose is 2.5mg. This increases in increments of 2.5mg until you reach 15mg. The dose is gradually increased to make sure you can cope with any side effects. You will need to stay on each dose for four weeks before you increase it.
If all goes to plan and you can tolerate the treatment, your dosing schedule will look like this:
| Week | Dosage |
| Weeks 1-4 | 2.5mg weekly |
| Weeks 5-8 |
5mg weekly |
| Weeks 9-12 |
7.5mg weekly |
| Weeks 13-16 |
10mg weekly |
| Weeks 17-20 |
12.5mg weekly |
| Weeks 21 onwards |
15mg weekly |
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What happens if you miss a dose of Mounjaro?
If you’ve missed a dose of Mounjaro® you should take the missed dose within 4 days after the missed dose. Try to take it as soon as possible after you’ve realised you’ve missed it.
If more than 4 days have passed since the missed dose, then skip it and take your next dose on your scheduled day. Make sure not to take 2 doses within 3 days of each other.
Mounjaro side effects
Like with all medications, there is a chance you may experience some side effects when taking Mounjaro. Common side effects may affect more than 1 in 10 people using the weight loss medication.
For more information, watch our video on Mounjaro's side effects.
Mounjaro® side effects often get better over time as your body gets used to treatment. You might find that you only experience side effects while your dose is being increased.
“When starting Mounjaro®, you’ll be prescribed a starting dose to begin with to allow your body to adjust to the medication and get used to side effects." - Dr Mitra Dutt
Potential side effects are broken down into common and uncommon:
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Common side effects |
Uncommon side effects |
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These side effects are usually not severe and often get better over time. They can be worse when starting treatment or going up a dose.
Learn more about the side effects of Mounjaro® by visiting the patient information leaflet.
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How to manage the side effects of Mounjaro
Side effects are usually mild. As your body gets used to the treatment any side effects are likely to lessen and disappear. Give your body a regular break between each treatment by injecting Mounjaro® on the same day every week.
To manage side effects:
- Eat smaller meals
- Eat more regularly
- Stop eating when you feel full
- Stay hydrated
- Avoid fat / fatty foods
- If you feel sick, sip water and eat plain foods like toast, crackers or rice
- Increase your fibre intake if you're constipated
- Exercise regularly
- If you're experiencing headaches you can take paracetamol
