Mounjaro Injection
Mounjaro weight loss injections (Tirzepatide) are the UK’s most effective prescription weight loss injection, clinically proven to help you lose up to 22% of your starting weight. It works by mimicking two hunger-relating hormones (GLP-1 and GIP) this means fewer cravings, smaller appetite and sustainable results.
You can buy Mounjaro through our GPhC-registered online pharmacy with free clinical support throughout your treatment.
Every weight loss treatment with The Family Chemist includes free access to online nutrition coaching powered by Nutrable. After your purchase is approved, you’ll receive your access code by email. You can also find your access code in your Family Chemist dashboard.
Prices starting from:
£164.99
Mounjaro Price
Mounjaro cost in the UK varies by dose. At The Family Chemist, we strive to offer our customers affordable private care, we regularly check our prices against competitors to ensure you’re getting the best value for money.
What is Mounjaro?
Mounjaro is a once-weekly injection that supports weight loss and long-term weight management. It reduces food cravings and appetite so you feel fuller for longer.
In Clinical trials adults taking the highest dose alongside diet and exercise lost up to ~22% of their bodyweight over 72 weeks.
The active ingredient is Tirzepatide. It mimics the action of two hormones, GLP-1 and GIP, that act on the areas of the brain involved in regulating appetite.
Mounjaro is available on prescription only in the UK, through licensed providers such as The Family Chemist.
Your journey
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After you choose your preferred treatment, our clinicians will review your consultation.
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“Every consultation is reviewed carefully to ensure treatment is safe, appropriate, and tailored to the individual. Patient wellbeing is always our priority.”
Sunny Dhain – Clinical Director | MRPharmS | PGDip | GPhC registered pharmacist
How do Mounjaro weight loss injections work?
Mounjaro targets two receptors in the body: GIP and GLP-1. Both are involved in regulating appetite, blood sugar and the way the body uses energy.
The GLP-1 receptor lowers appetite and supports blood sugar control, while the GIP receptor plays a part in energy balance and in how fat is stored and used.
Mounjaro activates both at once, which is why it may produce greater weight loss than the treatments targeting GLP-1 alone. This results in less hunger and more control over portion sizes.
How effective is Mounjaro?
- 5mg injection – 15.0% average weight lost
- 10mg injection – 19.5% average weight lost
- 15mg injection – 20.9% average weight lost
- Placebo saw a 3.1% average of weight lost.
Who can take Mounjaro?
Mounjaro is for adults who meet specific clinical criteria and can use it safely under medical supervision. You may be eligible if you:
Have a BMI of 30 kg/m² or above (clinically obese)
Have a BMI of 27–30 kg/m² with a weight-related condition such as high blood pressure, high cholesterol, pre-diabetes, or heart disease
Are from an ethnic background, where lower BMI thresholds may apply (typically from 27.5 kg/m²) due to increased metabolic risk
Are transferring from another provider and wish to continue treatment with us
Eligibility also depends on your current weight, health conditions, medication and medical history.
Complete an online consultation to check your eligibility today.
Can you get Mounjaro on the NHS?
Yes, but access is limited. Not every GP practice prescribes it, because availability depends on local NHS services and the eligibility criteria are strict.
The rollout is happening in phases over several years, with priority given to patients with the highest medical need. Many people will not yet qualify and may want to consider private treatment if they would rather start sooner.
Who Is Eligible for Mounjaro on the NHS?
To qualify during the initial launch, you need a BMI of 40 or above, plus at least four of the following:
- High blood pressure
- High cholesterol or abnormal blood fats
- Obstructive sleep apnoea
- Heart or cardiovascular disease
- Type 2 diabetes
Has Mounjaro been clinically tested?
The SURMOUNT-1 trial provides strong evidence for Mounjaro’s effectiveness in weight management. In this study, adults with obesity or who were overweight but did not have diabetes, experienced significant weight loss when using tirzepatide.
The results showed that Mounjaro weight loss injections can support meaningful weight reduction in eligible patients when used alongside diet and lifestyle changes. The trial also helped demonstrate its safety profile, although Mounjaro may not be suitable for everyone and should only be used following clinical assessment.
How long does Mounjaro take to work?
Most patients using Mounjaro weight loss injections notice early changes within the first 2 to 4 weeks, with more substantial results developing over 8 to 12 weeks as the dose is increased.
Average weight loss on different Mounjaro doses
Key points about Mounjaro weight loss injection results:
Early effects (2–4 weeks): Reduced appetite and improved portion control after starting the Mounjaro pen.
Progressive weight loss (8–12 weeks): Visible fat loss as the dose is titrated safely.
Maximum results (up to 72 weeks): Clinical studies show up to 22.5% body weight loss on the highest dose when injecting Mounjaro alongside lifestyle changes.
Dose escalation matters: Gradual increases help minimise side effects and improve long-term results.
Best outcomes: Achieved when Mounjaro injections are combined with a balanced diet and at least 150 minutes of weekly physical activity.
Additional benefits: Improvements in waist circumference, blood pressure, cholesterol levels, and insulin sensitivity.
How do I use Mounjaro weight loss injections?
Mounjaro is available in multiple dosages: 2.5mg, 5 mg, 7.5 mg, 10 mg, 12.5 mg, and 15 mg solutions for injection, each supplied in one pre-filled pen designed for easy use.
Before using Mounjaro, always read the instructions for use and the package leaflet provided with your pen for the latest information and guidance.
- Initial Phase: Start with 2.5 mg once weekly for the first four weeks.
- Titration: Increase the dose in 2.5 mg increments every 4 weeks as advised, up to a maintenance dose of 5 mg, 10 mg, or 15 mg weekly, depending on tolerance and response.
Concerned about giving yourself an injection?
“Many patients feel anxious about the idea of self-injecting at first. However, Mounjaro is designed to make the process as straightforward and comfortable as possible. It is supplied in a pre-filled pen device rather than a traditional syringe, making administration simple and controlled. The needle used is very fine and significantly smaller than those typically used for routine injections, and the pen mechanism delivers the dose, without the need for manual pressure.”
– Sunny Dhain MPharm, PGDip Independent Prescriber, Clinical Director
How to inject
We have a step-by-step guide for using the Mounjaro pen.
- Timing: once a week, ideally the same day and time to keep levels steady.
- Sites: the abdomen, upper thighs, or the outer part of the upper arms. Avoid veins and muscle, and rotate the site each week to reduce irritation.
- Preparation: use a new pen needle every time. Check the pen and needle for damage, and that the liquid is clear and colourless to slightly yellow.
- Disposal: put each used pen in a sharps bin.
Read the package leaflet supplied with your pen before your first injection.
What are the alternatives to Mounjaro?
Weight Loss Treatment Comparison
Several alternatives to Mounjaro are available for weight management, each using different active ingredients and mechanisms to support weight loss. The options below are commonly prescribed in the UK: To explore weight-loss treatments, visit our weight loss injections page and begin your medically supervised weight-management journey with guidance from our prescribing team.| Mounjaro | Wegovy | Liraglutide | Wegovy Tablets | Xenical | Orlistat | Alli | Mysimba | |
| Category | Injection | Injection | Injection | Tablet | Tablet | Tablet | Tablet | Tablet |
| Active Ingredient(s) | Tirzepatide | Semaglutide | Liraglutide | Semaglutide | Orlistat | Orlistat | Orlistat | Bupropion and Naltrexone hydrochloride |
| Mode of Action | GLP-1 receptor agonist and GIP mimetic | GLP-1 receptor agonist | GLP-1 receptor agonist | GLP-1 receptor agonist | Lipase inhibitor | Lipase inhibitor | Lipase inhibitor | Multimodal action |
| Administration | Once weekly | Once weekly | Once daily | Once daily | With meals | With meals | With meals | With meals |
| Dosage | Starting at 2.5mg, up to 15mg | Starting at 0.25mg up to 7.2mg | Starting at 0.6mg up to 3mg | Starting at 1.5mg up to 25mg | One up to three times a day | One up to three times a day | 60mg up to three times a day | One to four tablets a day |
| Weight Loss % | Up to 21% to 22.5% | About 21% | About 5% to 10% | About 14% to 20% | About 5% to 10% | About 5% to 10% | About 5% | About 5% to 10% |
| Common Side Effects | Nausea, indigestion, diarrhoea, vomiting, constipation, stomach pain | Nausea, indigestion, diarrhoea, vomiting, constipation, stomach pain | Nausea, hypoglycaemia, diarrhoea, constipation, headache, decreased appetite | Nausea, indigestion, diarrhoea, vomiting, constipation, stomach pain | Oily spotting, gas with discharge, faecal urgency, fatty/oily stool | Similar to Xenical: Oily spotting, gas, faecal urgency | Similar to Xenical but may be milder due to lower dose | Nausea, constipation, headache, dry mouth, dizziness |
| Manufacturer | Eli Lilly | Novo Nordisk | Generic | Novo Nordisk | Haleon | Generic | Not specified | Not specified |
Troubleshooting a Mounjaro Pen
Eli Lilly publishes troubleshooting guidance for the KwikPen. The three things patients ask us about most:
- Air bubbles are normal and do not affect the dose.
- Room temperature is not required. There is no need to warm the pen first.
- A drop of liquid or blood after injecting is normal. Press gently with cotton wool or gauze, without rubbing.
Monitoring and Adjustments
- Monitor your body’s response to Mounjaro. Adjustments to the dosage may be necessary based on effectiveness and side effects.
- If adding Mounjaro to other diabetes medications like sulphonylureas or insulin, monitoring and dose adjustments may be needed to reduce the risk of hypoglycemia.
Who cannot use Mounjaro?
You cannot use Mounjaro if you:
- Are pregnant or planning pregnancy
- Are breastfeeding
- Are over 75 years old
- Have severe stomach or gut conditions such as severe gastroparesis (where the stomach empties too slowly)
- Have certain types of diabetic retinopathy (an eye condition related to diabetes)
- Have been diagnosed with acute pancreatitis
Use Mounjaro with caution if you:
Have a history of pancreatitis
Mounjaro has not been widely studied in patients with previous pancreatitis. Stop treatment immediately and seek medical help if you develop severe stomach pain, nausea, or vomiting.
Take diabetes medication
Using Mounjaro alongside diabetes medication such as insulin or sulphonylurea medicines can increase the risk of low blood sugar (hypoglycaemia). Your prescriber may need to adjust your dose and monitor you closely.
Experience severe gastrointestinal side effects
Common side effects such as nausea, vomiting, or diarrhoea can lead to dehydration, which may affect kidney function — particularly in older adults. Staying well hydrated is important.
Take other oral medications
Mounjaro can slow stomach emptying and affect how some oral medicines are absorbed, especially medicines where the dose needs to be very precise to work safely. Your prescriber may review your medication regimen.
Mounjaro side effects
What are the most common side effects of Mounjaro?
- Diarrhea
- Nausea
- Vomiting
- Constipation
- Low blood sugar – particularly when taken with certain diabetes medications.
Can Mounjaro Cause Low Blood Sugar?
- Shaking
- Sweating
- Dizziness
- Hunger
- Rapid heartbeat.
It’s important to inform your doctor if you experience these symptoms.
Other common side effects of Mounjaro
- Faster pulse
- Allergic skin reactions such as rash, itching or eczema
- Stomach pain
- Indigestion
- Bloating
- Burping or wind
- Heartburn or acid reflux
- Feeling tired
- Low blood pressure
- Hair loss
- Irritation, itching or redness where the injection was taken
- Changes in blood test results – increased pancreatic enzymes
Uncommon side effects of Mounjaro
What are the long-term side effects of Mounjaro?
What should I do if I experience serious side effects from Mounjaro?
- Pancreatitis
- Allergic reactions
- Gallbladder problems
If you experience any symptoms of these such as breathing difficulties, swelling of the throat, face, and mouth, fainting, severe stomach and back pain, then stop taking Mounjaro and seek medical help immediately.
This is not a full list of possible side effects. Always read the patient information leaflet before using Mounjaro so you understand the possible side effects, warnings and precautions and if you experience side effects not listed above, complete a MHRA Yellow Card report.
What is the difference between Mounjaro and Wegovy?
Mounjaro and Wegovy are both weekly weight-loss injections that help reduce appetite, make you feel fuller and support long-term weight loss. The main difference is the active ingredient used and how they work in the body.
Mounjaro contains Tirzepatide, which targets two hormones (GLP-1 and GIP). These hormones help control appetite, fullness and blood sugar levels.
Wegovy contains Semaglutide, this only targets the GLP-1 hormone which helps to reduce hunger and make you feel fuller for longer.
Both weight loss injections are effective but the right option depends on your weight-loss goals, and how well you tolerate the treatment. Our clinicians will help you decide which treatment is most suitable for you.
Can I switch between Mounjaro, Wegovy and Wegovy Tablets.
Yes. Please see below dose equivalences.
Does Mounjaro affect the contraceptive pill or HRT?
Mounjaro (tirzepatide) slows stomach emptying, which can affect how well some oral medications are absorbed.
Oral contraceptive pills: Mounjaro may reduce the effectiveness of oral contraceptives, particularly when starting treatment and after each dose increase. If you take an oral contraceptive pill, you should use a barrier method of contraception, such as condoms, for 4 weeks after starting Mounjaro and for 4 weeks after each dose increase. Alternatively, you may wish to consider a non-oral contraceptive method.
Oral HRT: Mounjaro may also affect the absorption of oral HRT tablets. If you are taking oral HRT, you should inform your GP or HRT prescriber that you are starting Mounjaro. They can advise whether any monitoring, treatment adjustments, or alternative formulations of HRT may be appropriate.
If you experience a return or worsening of menopausal symptoms, new breakthrough bleeding, or any other unexpected changes after starting Mounjaro or increasing your dose, you should seek medical advice.
These considerations are most relevant during the first 4 weeks after starting Mounjaro and for 4 weeks following each dose increase.
Mounjaro treatment starts at 2.5mg once a week. You will usually stay on this dose for the first 4 weeks. This gives your body time to adjust and may help reduce early side effects.
After 4 weeks our clinician may increase your dose to 5mg once a week. If you need more support and are tolerating the treatment well, your dose may then be increased gradually by 2.5mg at a time. You will usually stay on each dose for at least 4 weeks before moving up.
The highest approved adult dose is 15mg once a week. The UK patient leaflet and EMA product information both describe this step-up dosing schedule.
You should only increase your dose when advised to. Increasing your dose too quickly or taking more than prescribed can increase the chance of side effects such as feeling sick, stomach discomfort, dehydration, and tiredness.
Not everyone needs to reach the highest dose. Some people get good results on a lower or middle dose and prefer to stay there, especially if it helps them manage side effects. Higher doses may provide more appetite control for some people, but they may also increase the chance of side effects and cost more.
What is the Mounjaro maintenance dose?
A Mounjaro maintenance dose is the dose you stay on long term to help maintain the weight you’ve lost.
The recommended maintenance doses are usually 5mg, 10mg or 15mg once a week. The right dose can vary from person to person and will depend on your progress, side effects and how well you tolerate the treatment.
Not everyone needs to reach the highest dose. Many people stay on the dose that gives them steady results while keeping side effects manageable.
Our clinicians will help decide which maintenance dose is most suitable for you.
How to buy Mounjaro online in the UK
You can buy Mounjaro weight loss injections online once a clinician has assessed you and issued a prescription.
Start with a consultation covering your health, current medications, weight, and goals. Our clinicians review every consultation and will come back to you with questions if anything needs explaining.
After that, your online account is where you check progress and message our clinical team.
Where should you buy Mounjaro?
Only buy Mounjaro from a regulated UK pharmacy or an approved healthcare provider. With The Family Chemist, your consultation is reviewed by a qualified prescriber, and if treatment is approved, you get clear guidance and ongoing support for as long as you are with us.
You also get a free support programme built by our in-house nutritionists and clinicians: practical advice on eating well, physical activity and building habits that last, plus trackers and goal-setting tools to keep you organised.
If you have any questions during treatment, our clinical team is here to provide clear and reliable support.
Start your weight-loss journey with confidence
Starting treatment with The Family Chemist is simple, secure and guided by our clinical team.
Complete a short online medical questionnaire
Our prescribers review your information to check if treatment is suitable
Receive personalised next steps and access to your free support package
Request your treatment securely online
Take the first step towards a healthier weight with expert support from The Family Chemist. Start your consultation now.
Sources
- Tirzepatide once weekly for the treatment of obesity in people with type 2 diabetes (SURMOUNT-2): a double-blind, randomised, multicentre, placebo-controlled, phase 3 trial (2023) The Lancet [accessed 9th February 2026]
- Tirzepatide Once Weekly for the Treatment of Obesity (2022) The New England Journal of Medicine [accessed 9th February 2026]
- Mounjaro 2.5/5/7.5/10/12.5/15mg KwikPen solution for injection in pre-filled pen (2024) EMC: Patient Information Leaflet [accessed 9th February 2026]
- Wegovy 0.25 mg, FlexTouch solution for injection in pre-filled pen, emc [accessed 9th February 2026]
- A Study of Tirzepatide (LY3298176) in Participants With Type 2 Diabetes Who Have Obesity or Are Overweight (SURMOUNT-2) (2024) Clinical Trials [accessed 9th February 2026]
- A Study of Tirzepatide (LY3298176) In Participants After A Lifestyle Weight Loss Program (SURMOUNT-3) (2024) Clinical Trials [accessed 9th February 2026]
- Continued Treatment With Tirzepatide for Maintenance of Weight Reduction in Adults With Obesity (2024) JAMA [accessed 9th February 2026]
- Mounjaro is the first in a new class for the treatment of type 2. Diabetes (2023) Mounjaro [accessed 9th February 2026]
- How to use Mounjaro (2023) Mounjaro [accessed 9th February 2026]
- MHRA authorised diabetes drug Mounjaro (tirzepatide) for weight management and weight loss (2023) GOV.UK. [accessed 9th February 2026]
- Effectiveness of Dulaglutide in the Real World and in Special Populations of Type 2 Diabetic Patients (2020) NIH [accessed 9th February 2026]
- Lilly’s SURMONT-2 results published in The Lancet show tirzepatide achieve a mean weight reduction of 15.7% at the highest dose (15mg) in adults with obesity or overweight and type 2 diabetes (2023) Eli Lilly [accessed 9th February 2026]
- Tirzepatide for managing overweight and obesity (2024) NICE [accessed 9th February 2026]
- Two-year effects of semaglutide in adults with overweight or obesity: the STEP 5 trial (2022) Nature Medicine [accessed 9th February 2026]
- Once-Weekly Semaglutide in Adults with Overweight or Obesity, The New England Journal of Medicine [accessed 9th February 2026]
Medically
reviewed by
Tannaz Sohrabi (MPharm, PGDip, IP, MRCPharm)
GPhC Number: 2225756
Last reviewed: 17th April 2026
Meet our
medical professionals
Aaliyah Nelson
Nutritional Coaching
BSc (Hons) Nutrition: 47988
Standards first
always
