Mounjaro Weight Loss Injections

If you’re considering treatment for weight management, it’s important to understand how your treatment options work and whether they’re suitable for you. Medication isn’t always necessary, but in some cases it can be considered alongside lifestyle changes as part of a broader, clinically guided approach.

What Is Mounjaro?

Mounjaro is a prescription-only GLP-1 treatment that contains tirzepatide. It was first developed to help manage type 2 diabetes, but it’s now also approved to help support weight loss.

It works by acting on two natural hormones in the body: GLP-1 (glucagon-like peptide-1) and GIP (glucose-dependent insulinotropic polypeptide). Mounjaro:

• Targets the area of the brain responsible for appetite control, helping to make you feel fuller for longer and reduce overall calorie intake.
• Lowers blood sugar levels, prompting the pancreas to release more insulin.
• Slows digestion by delaying the rate that food leaves the stomach, keeping you fuller for longer and preventing blood sugar spikes.
• Reduces cravings and “food noise”

Mounjaro is intended to be used in conjunction with healthy lifestyle changes.

Who Manufactures Mounjaro

Mounjaro is manufactured by the US pharmaceutical company Eli Lilly, which was founded in 1876.

Eli Lilly launched Mounjaro in May 2022 after it was approved in the US to treat type 2 diabetes. It quickly gained attention for weight loss benefits and the active ingredient, tirzepatide, was approved for weight loss in both the US and the UK in November 2023. Since the launch of Mounjaro, Eli Lilly has rapidly expanded manufacturing to keep up with demand.

Who Can Use Mounjaro? (Eligibility)

Mounjaro may be suitable for adults who are overweight or living with obesity and would benefit from additional support with weight loss.

Mounjaro may be suitable if you:

• Have a body mass index BMI of 30 or above
• Have a BMI of 27 or above and you have a weight-related health condition, such as high blood pressure or type 2 diabetes

Mounjaro may not be suitable if you:

• Are pregnant or breastfeeding
• Have certain medical conditions affecting your pancreas or digestive system
• Are taking medicines that may interact with tirzepatide

A prescriber also needs to check your medical history. This includes your current medicines, whether you are pregnant or breastfeeding, and whether there are any reasons that another treatment may be safer.

How Does Mounjaro Work?

Mounjaro contains tirzepatide, which mimics the effects of two natural hormones in your body called GLP-1 (glucagon-like peptide-1) and GIP (glucose-dependent insulinotropic polypeptide). These hormones are released after eating and help regulate appetite and blood sugar levels. GLP-1 receptor agonists have been shown to improve blood sugar control and support weight loss.

Mounjaro works in three key ways:

Reducing appetite:
Tirzepatide activates GLP-1 and GIP receptors in the brain, helping you feel fuller after eating. This can reduce hunger, curb cravings, and make it easier to manage portion sizes.

Slowing digestion:
It slows how quickly food leaves your stomach (gastric emptying), which helps you stay satisfied for longer and may reduce the urge to snack between meals.

Regulating blood sugar:
Mounjaro supports insulin release after eating and reduces the amount of glucose released by the liver. This helps keep blood sugar levels more stable and can reduce hunger spikes.

Together, these effects can make it easier to eat fewer calories and maintain a calorie deficit, which is essential for weight loss.

How Long Do Mounjaro Injections Take To Work?

Mounjaro doses are increased gradually to get your body used to the medication and minimise side effects.

Month 1: Many people may notice a change in their appetite over the first couple of weeks, with measurable weight loss between 2–4 weeks.

Month 2: You may start losing 0.5-1kg a week or around 5% of your body weight - 50% of people will have lost 5% body weight.

Month 3: At this point, most people will have lost 5% of their body weight.

How Effective Is Mounjaro?

Mounjaro produces average weight loss of 15–22% over 72 weeks in people with obesity or overweight, as shown by the SURMOUNT-1 trial. In people with type 2 diabetes, weight loss is lower at around 13–16% but still clinically significant. When combined with lifestyle changes, as shown in SURMOUNT-3, total weight loss exceeds 20%.

SURMOUNT-4 shows that continued treatment is necessary to maintain Mounjaro benefits, otherwise there is likely to be significant weight regain at around 14%.

Mounjaro in Clinical Studies

What Happens When I Stop Taking Mounjaro?

What Happens When I Stop Taking Mounjaro?

When you stop taking Mounjaro, its effects on appetite and blood sugar control will gradually reduce. This means your hunger levels may return to where they were before treatment.

Clinical studies have shown that some people may regain weight after stopping tirzepatide, particularly if lifestyle changes are not continued. For this reason, treatment is usually used alongside longer-term changes to diet and physical activity.

If you’re thinking about stopping Mounjaro or switching to a different weight-loss treatment, our UK-registered expert pharmacists can provide trusted advice and personalised support every step of the way.

How To Use Mounjaro Weight Loss Injections

The prospect of using weight loss pens can feel slightly daunting, especially when it’s your first time.
However, once you get into a routine, most people find it straightforward and easy to manage. Mounjaro is designed to be simple to use at home, and you’ll be guided on exactly how to take it safely.

Where To Inject Mounjaro

Mounjaro is injected just under your skin, and you can use your stomach (abdomen), upper thigh or upper arm. You may prefer the stomach or thigh because they’re easier to reach on your own.

If you’re using your upper arm, you may need someone to help you. You can use the same general area each week, but make sure you change the exact injection site each time to help reduce irritation.

How To Inject Mounjaro Step-By-Step

1. Allow the pen to get to room temperature for 30 minutes before using. This should minimise any stinging or discomfort.
2. Wash your hands with soap and water.
3. Prepare the pen. Check for damage and the liquid looks clear – if it’s not clear, the pen looks damaged or you believe it could have been frozen, do not use it.
4. Attach a new needle to the pen.
5. Turn the dose switch until you hear 2 clicks.
6. Prime the pen by holding the pen with the needle pointing up to collect air bubbles at the top.
7. Adjust the dosage to ‘1’.
8. Insert the needle, push down the dose knob and slowly count to 10.
9. Pull the needle out. Check the dose count is back to ‘0’.
10. Remove the needle and dispose of it in your sharps bin.
11. Replace the pen’s cap.

You can read in more detail our How To Use The Mounjaro Kwikpen guide.

How The Mounjaro Kwikpen Makes Self-Injecting Simple

The Mounjaro Kwikpen is designed to may weekly self injections as easy as possible.

• The pen contains the precise amount of medication so there’s no need to draw the medicine into a syringe.
• The dose window lets you know when the dose has been fully administered.
• The needle is hidden in the pen, so you don’t need to see it.
• The autoinjector means it will inject properly with minimum force.

How long do I have to stay on Mounjaro?

Mounjaro is designed for long term use. Typically maintenance doses are used to help you stay at a healthy weight and BMI.

How often should Mounjaro be taken?

Mounjaro should be taken once a week, on the same day of the week. It can be taken at any time of the day, with or without food.

Select a time and day that is easy for you to remember. You could set a reminder on your phone so you don’t miss a dose.

What happens if I miss a dose?

If you miss a dose of Mounjaro and it’s been less than 4 days/96 hours, take your missed dose. If you’ve missed your dose by more than 4 days/96 hours, skip it and wait for your next dose.

Never take 2 doses at once to make up for a missed dose.

Mounjaro Injections Dosage Guide

Mounjaro injections are available in the following 6 dosages:

• 2.5mg
• 5mg
• 7.5mg
• 10mg
• 12.5mg
• 15mg

Most people start on 2.5mg once a week for the first four weeks. After that, it’s usually increased to 5mg once a week.

If needed, your prescriber may gradually raise your dose in 2.5mg steps, up to a maximum of 15mg, usually leaving at least four weeks between each increase.

You will not always need the highest dose. The aim is to find the dose that works well for you while keeping side effects manageable.

The Mounjaro Maintenance Dose

After starting Mounjaro, your dose is gradually increased to help your body adjust. Once you reach a dose that works well for you - with minimal side effects - you’ll be prescribed a maintenance dose. This could be 5mg, 10mg or 15mg depending on your individual response and tolerability.

People typically need a maintenance dose because obesity is a chronic condition, not a short term issue. In the SURMOUNT-4 clinical trial, people who stopped tirzepatide regained around 14% of body weight, while those who continued lost additional weight (around 26% total loss from baseline). Without maintenance, hunger and cravings return and weight gradually increases.

Your maintenance dose will help keep your weight stable. You can read more in our How Does the Mounjaro Maintenance Dose Work guide.

Mounjaro Injections Ingredients

Active ingredient: tirzepatide

Other ingredients: sodium phosphate dibasic heptahydrate, benzyl alcohol, glycerol, phenol, sodium chloride, sodium hydroxide, concentrated hydrochloric acid and water for injections.

For the most up-to-date list of ingredients, please check the Patient Information Leaflet inside the box.

Side Effects of Mounjaro Injections

Like all medications, Mounjaro can cause side effects, although not everyone will experience them.

The most common side effects are digestive and include:

• Nausea
• Diarrhoea
• Vomiting
• Stomach (abdominal) pain
• Constipation

These are usually mild to moderate and are more likely to occur when starting treatment or increasing the dose.

Other side effects can include:

• Indigestion
• Feeling more tired than usual
  
  

In rare cases, more serious side effects can occur, including:

• Inflammation of the pancreas (pancreatitis)
• Severe allergic reactions
• Gallbladder problems
  
  

If you have any concerns about side effects, you can discuss these with our experienced pharmacists, who are available to provide guidance and support. Where appropriate, they can recommend suitable treatments for conditions such as nausea and diarrhoea, helping you stay comfortable while continuing your plan.

You can read more in our Managing Common Side Effects of Mounjaro guide.

Mounjaro Injections Warnings & Interactions

Mounjaro may not be suitable for everyone. You should not use it if:

• You are allergic to tirzepatide or any of the ingredients
  
  

You should speak to a healthcare professional before using Mounjaro if you:

• Are pregnant, think you may be pregnant or are planning a pregnancy
• Are breastfeeding or planning to breastfeed
• Have a history of pancreatitis
• Have severe digestive problems
  
  

Important:

• Mounjaro may affect how well oral contraceptives work, so additional contraception may be needed
  
  

For full details, including all warnings and possible side effects, please see the Patient Information Leaflet.

What Are The Best Mounjaro Alternatives? (Comparison)

Mounjaro isn’t the only option available if you’re looking for support with weight loss, and it may not be the right fit for everyone. Information about other weight loss injections and oral tablets is also available if you’d like to compare treatment options.

Other treatments include:

• Wegovy Weight Loss Injection
• Orlistat 120mg Capsules
• Nevolat Daily Weight Loss Injection
• Xenical 120mg Capsules
• Mysimba 8mg/90mg Prolonged-Release Capsules
• Alli 60mg Capsules
• Ozempic Injections
  
  

There’s also a new tablet alternative to the Wegovy injection:

• Wegovy Pill

This treatment is currently awaiting approval from the MHRA in the UK. If you’d like to be kept informed about when this treatment becomes available, you can sign up for our email updates here.

These options may be more suitable depending on your medical history, your goals and how you respond to treatment. Some people also consider alternatives if they experience side effects, reach a plateau or are looking for a more cost-effective option.

If you’re unsure which treatment is right for you, a prescriber can review your individual situation and help you choose an option that feels manageable and aligned with your goals.

Mounjaro Injections vs Wegovy Injections (Comparison)What Is the Difference Between Mounjaro and Wegovy?

If you’re weighing up Mounjaro vs Wegovy, a number of factors may be crossing your mind, price, subscription models and – most importantly – how they work for your body.

Mounjaro acts on two appetite-related hormones, GIP and GLP-1, while Wegovy works on GLP-1 only. That might not sound like much, but it can affect how full you feel, how hungry you get and how easy it is to eat less.

Mounjaro vs Wegovy Injections: Comparison

If you’re looking for a bit more guidance, you can explore our guides How Do Mounjaro and Wegovy Compare for Weight Loss? and Can I Switch from Mounjaro to Wegovy?

Can I Switch Between Mounjaro and Wegovy Injections?

Yes, you can switch between Mounjaro and Wegovy, but it’s important to do so with support from a healthcare professional.

Although both treatments are once-weekly injections that can help manage your appetite and support weight loss, they contain different active ingredients and have different dosing schedules. This means you cannot swap them on a like-for-like basis or use them together.

If you do switch, you will usually have a short break before starting your new treatment, and your dose will be carefully adjusted based on how you have been responding to it, including any side effects.

If you have any questions about switching, The Independent Pharmacy’s UK-based prescribers can provide expert advice and guide you through the safest way to make the change.

Mounjaro vs Ozempic Injections: Comparison

If you’re deciding between Mounjaro and Ozempic, it helps to understand what each treatment is designed for, as well as how they’re typically prescribed.

What Is the Difference Between Mounjaro and Ozempic Injections?

Mounjaro is licensed for weight management in the UK, meaning it can be prescribed to support weight loss alongside healthy lifestyle changes.

Ozempic, on the other hand, contains semaglutide and is primarily prescribed to help manage blood sugar levels in people with type 2 diabetes. It is not licensed for weight loss, although some people may notice changes in appetite and weight while using it.

In certain cases, it may be prescribed off-label (meaning for a use outside its licence), depending on a clinician’s judgement.

They also work slightly differently in the body. Mounjaro targets two hormones involved in appetite regulation, GIP and GLP-1, while Ozempic works on GLP-1 alone, similar to Wegovy.

Mounjaro vs Ozempic Injections: Comparison

Mounjaro Injections vs Wegovy Pill: Comparison

Can I Switch From Mounjaro Injections to the Wegovy Pill?

Yes, you can switch from Mounjaro injections to the Wegovy pill, if the Wegovy pill becomes available in the UK. To make the switch, you would need to speak to your prescriber so they can make sure you do so in a clinically safe and appropriate way.

How To Buy Mounjaro Online

If you’re considering Mounjaro, it’s important to obtain it from a regulated UK pharmacy. This helps ensure your treatment is safe, appropriate and supported by qualified healthcare professionals.

Buying from unregulated or non-verified sources can put your health at risk. Medicines sold outside of regulated pharmacies may not be genuine, stored correctly or meet UK safety standards.

When you choose a regulated pharmacy, you can feel more confident that:

• Your treatment is genuine and sourced through approved supply chains
  
  
• Your prescription is reviewed by qualified healthcare professionals
  
  
• You have access to advice and support if you experience side effects
  
  
• You’re receiving accurate, up-to-date medical information

At The Independent Pharmacy, all treatments are prescribed following an online consultation and reviewed by our clinical team. You’ll also have access to our Health Hub, filled with clinically accurate health information, expert advice and practical support to help you feel confident and informed throughout your weight loss journey.

How do I get a prescription for Mounjaro?

To get a private prescription for Mounjaro, you need to complete our online assessment. You’ll need to answer some questions and send us some photos. Our pharmacists will then review your information to make sure that Mounjaro may be a safe and suitable weight loss option for you.

Can you get Mounjaro on the NHS?

Mounjaro is available on the NHS. However, you need to meet very strict criteria and it’s strictly rationed to those with the highest clinical need. According to NICE guidelines, you need:

• A BMI over 35
• Plus, one weight related health condition, such as high blood pressure or type 2 diabetes

To get Mounjaro on the NHS, make a GP appointment and your GP will refer you if they believe you meet the criteria.

Mounjaro Injections 2025 Price Increase

You may have noticed that the price of Mounjaro has changed over time. This is something that can happen with newer treatments, especially as demand increases and availability changes.

From 1 September 2025, the manufacturer of Mounjaro, Eli Lilly, increased prices across the UK to bring them in line with other European countries. Because Mounjaro is supplied by a single manufacturer, this change has affected all providers.

If you’re currently using Mounjaro or thinking about starting, it’s worth keeping in mind that prices can vary depending on the dose you’re prescribed and the provider you choose. If cost is a concern for you, it’s a good idea to speak to a prescriber about your options, as there may be alternative treatments or dosing plans that better suit your budget.

How Much Will My Weight Loss Journey Cost?

The cost of your weight loss journey with Mounjaro will depend on a few key factors, including your starting dose, how your dose is increased over time and how long you stay on the treatment.

Most people begin on a lower dose and gradually increase, which means your monthly cost may rise as your treatment progresses. It’s also worth remembering that weight-loss treatments are usually part of a longer-term plan, so it helps to consider affordability over time, not just the starting price.

If you’re unsure, a prescriber can help you understand what your treatment plan might look like and what you can expect to pay as you move through each stage.

How Often Do I Need To Do a Consultation?

Before starting Mounjaro, you’ll need to complete a consultation so a prescriber can check that it’s safe and suitable for you.

After that, you won’t usually need to repeat a full consultation each time you reorder, but your treatment will still be reviewed regularly. This helps ensure the medication is working well for you, your dose is appropriate and you’re not experiencing any side effects that need attention.

If anything changes with your health, your weight loss progress or how you’re tolerating the treatment, you may be asked to complete another consultation so your plan can be safely adjusted.