Mounjaro (tirzepatide) is a once-weekly injection that helps you lose weight by targeting hormones that regulate appetite and blood sugar. It's clinically proven to help you lose weight and improve your health.
Mounjaro® Weight Loss Injections
(tirzepatide)
Clinically proven to help you lose weight and improve your health.

- 4 weekly doses
- Includes clinical review
- Cold-chain delivery
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UK registered cliniciansCare from qualified professionals
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Fast, tracked deliveryDiscreet and reliable
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Ongoing supportHere when you need us
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Sharps bin includedSafe and convenient
New to Mounjaro
Complete your eligibility assessment to see if Mounjaro is right for you.
Start assessmentAlready taking Mounjaro
Switch using evidence of your current prescription and dose.
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Clinically reviewed facts
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Active ingredientTirzepatide
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Weekly injectionOnce a week
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Six strengths2.5 mg – 15 mg
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UK clinician reviewPrescribed if suitable
Your treatment, supported from day one
A simple, secure process with expert care at every step.
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1
Complete your assessment
Tell us about your health, goals and lifestyle. It only takes a few minutes and is completely confidential.
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2
Clinician reviews your details
A UK-registered clinician will review your assessment and recommend the right treatment for you.
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3
Delivered discreetly
Once approved, your medication is sent in discreet packaging, with ongoing support whenever you need it.
How Mounjaro works
Mounjaro (tirzepatide) helps to reduce appetite and increase feelings of fullness, and Happy Pharmacy provides ongoing support to help you build healthier routines for the long term.
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Reduces appetite
Helps you feel less hungry and eat less.
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Increases fullness
Helps you feel fuller for longer so you're less likely to snack between meals.
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Supports healthier habits
Our clinical team and resources help you build sustainable routines.
Mounjaro doses at a glance
Six strengths, prescribed gradually according to your response and clinical review.
Mounjaro key points
- Treatment usually starts at 2.5 mg
- One injection, once each week
- Four weekly doses in every KwikPen
- Dose increases only following clinical review
Mounjaro dose schedule
Most people start on 2.5 mg and may increase the dose every 4 weeks, subject to clinical review.
- 2.5 mg Weeks 1–4Start
- 5 mg Weeks 5–8
- 7.5 mg Week 9+If needed
- 10 mg Week 13+If needed
- 12.5 mg Week 17+If needed
- 15 mg Week 21+If needed
Your clinician will only increase your dose when appropriate. Not everyone needs the highest dose.
Your weight loss journey.
All in one place.
Manage your treatment, track your progress and see your Happy Rewards in the Happy Pharmacy app.
- Manage your treatment
- Track your progress
- View your rewards
Important safety information
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Who may be suitable
Mounjaro is for adults with a BMI of 30+ or 27+ with weight-related health conditions. A clinical assessment is required to confirm suitability.
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Common side effects
Nausea, diarrhoea, constipation, vomiting and stomach upset are common, especially when starting treatment. These usually improve over time.
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When to seek help
Seek urgent medical advice if you have severe or persistent stomach pain, signs of dehydration, or symptoms of pancreatitis (such as severe abdominal pain).
What is Mounjaro® and how does it work?
Mounjaro® is a prescription-only medicine containing tirzepatide. It is given as a once-weekly injection under the skin. It is licensed in the UK for weight management in eligible adults and also has a separate indication for treating type 2 diabetes.
How does Mounjaro help with weight loss?
Tirzepatide activates receptors for two naturally occurring hormones, GIP and GLP-1, involved in appetite and blood-sugar regulation. It can reduce hunger and help you feel fuller, so you eat less. It also delays stomach emptying, although this effect reduces over time.
Is Mounjaro approved for weight loss?
Yes. Its UK weight-management licence covers adults with an initial BMI of 30 or above, or 27 or above with at least one weight-related health condition. It is used alongside a reduced-calorie diet and increased physical activity. You do not have to have diabetes to qualify for weight-management treatment. For practical meal ideas, see our guide to what to eat on Mounjaro.
You can buy Mounjaro online from Happy Pharmacy following a consultation and prescriber approval. We also offer assessments for other prescription weight loss medications. A prescriber reviews your medical history, current medicines and individual circumstances before deciding whether treatment is suitable. Completing an assessment does not guarantee a prescription.
*SURMOUNT-1 studied adults with obesity, or overweight with a weight-related complication, without diabetes. Participants also received support with diet and physical activity. The 20.9% figure is the average reduction in starting body weight in the 15 mg group at 72 weeks, compared with 3.1% with placebo. Results vary; this is not a guaranteed outcome or a reason to increase your dose. Significant weight loss can also change body shape, and loose skin on Mounjaro may become more noticeable after a substantial reduction. SURMOUNT-1 trial results.
How is it different from Wegovy®?
The Wegovy® weight-loss injection contains semaglutide, which acts on GLP-1 receptors. Mounjaro contains tirzepatide, which acts on both GIP and GLP-1 receptors. These medicines have different dosing schedules and are not interchangeable. A prescriber can help assess which treatment is appropriate for you. For a fuller comparison, read our Mounjaro vs Wegovy guide. If you are comparing Mounjaro with the daily tablet, read our Wegovy pill vs Mounjaro guide.
What do Mounjaro® weight-management studies show?
Mounjaro has been studied in large clinical trials involving adults living with obesity, or adults who were overweight with a weight-related health condition. Trial results describe averages across groups; they cannot predict the result for an individual person.
*These figures use the SURMOUNT-1 treatment-regimen analysis. The study ran for 72 weeks and included dietary and physical-activity support. They are not guaranteed outcomes and should not be used to decide a dose.
What happened in SURMOUNT-1?
SURMOUNT-1 included 2,539 adults with obesity, or overweight with a weight-related complication, who did not have diabetes. Participants received once-weekly tirzepatide or placebo for 72 weeks alongside lifestyle support.
- Average weight reduction was 15.0% with 5 mg, 19.5% with 10 mg and 20.9% with 15 mg.
- Average weight reduction in the placebo group was 3.1%.
- Results differed between participants. Some people lost less or more than the average, and some stopped treatment before the study ended.
- Trial participants followed a reduced-calorie diet and increased physical activity, so the results do not show the effect of medicine alone.
When might you notice a change?
There is no fixed week-by-week weight-loss pattern. Appetite changes, side effects and weight change vary between people. Your prescriber may keep you at a dose for longer than four weeks, or decide that an increase is not appropriate.
| Treatment period | What may happen | What to do |
|---|---|---|
| Starting treatment | Your body adjusts to treatment. Some people notice appetite changes; others do not notice a clear change straight away. | Take the prescribed dose weekly and report troublesome side effects. |
| Dose review | Your prescriber considers response, side effects and your wider health before deciding whether to continue or increase the dose. | Do not increase, skip or repeat a dose without advice. |
| Ongoing treatment | Weight change can be uneven. Plateaus and changes in appetite can occur during treatment. | Attend reviews and discuss any treatment gap, side effects or concern about progress. |
| Type of Low Blood Sugar Event | 5 mg | 10 mg | 15 mg | Placebo |
|---|---|---|---|---|
| Serious low blood sugar (needed help from another person) | 0% | 0% | 0% | 0% |
| Very low blood sugar reading (below clinical threshold) | 0% | 0% | 0% | 1% |
| Pathway | Who It's For | Min. BMI | What This Means |
|---|---|---|---|
| 1a | Starting fresh — standard | ≥ 30 | A BMI of 30 or above is classed as obesity. No other health condition needed to qualify. |
| 1b | Starting fresh — with a health condition | ≥ 27 | A BMI of 27–29.9 can qualify if you also have a weight-related health condition (such as high blood pressure, type 2 diabetes, sleep apnoea, or others). |
| 1c | Starting fresh — adjusted for ethnicity | ≥ Threshold −2.5 | People from certain ethnic backgrounds carry a higher health risk at any given BMI. NHS guidance (NICE NG246) recommends a threshold 2.5 points lower for South Asian, Chinese, other Asian, Middle Eastern, Black African, and African-Caribbean backgrounds. |
| 2 | Switching from another provider | ≥ 21 | Already on a weight loss injection elsewhere? You can transfer if you have proof of your previous prescription, have lost at least 5% of your starting weight, and originally met Pathway 1 criteria. |
| 3 | Staying at target weight (maintenance) | ≥ 20 | If you've reached your target weight and it has been stable for 8–12 weeks, you may continue on the lowest dose that keeps you there. We will never prescribe below a BMI of 20. |
- Your BMI is 30 or above (Pathway 1a)
- Your BMI is 27+ with a qualifying health condition (Pathway 1b)
- Your BMI meets standard threshold minus 2.5 points with qualifying ethnic background (Pathway 1c)
- You're 18 or older
- You're not pregnant or breastfeeding
- You're willing to make some healthy changes to your diet and activity
- You're switching from another UK provider and have lost at least 5% already (Pathway 2, BMI ≥21)
- You are pregnant, trying to get pregnant, or breastfeeding
- You have type 1 diabetes
- You're already taking another weight loss injection (e.g. Wegovy®, Ozempic®)
- You have, or have had, pancreatitis
- You or a close family member have had medullary thyroid carcinoma (MTC) or MEN2
- You have severe problems with your stomach or gut emptying
- You are allergic to tirzepatide or any ingredients in Mounjaro®
- Your BMI is below 20 at any point during treatment
How to inject Mounjaro® KwikPen
This overview supports, but does not replace, the manufacturer’s full KwikPen instructions. Read them before use and ask your pharmacist to demonstrate anything you are unsure about.
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Prepare
Wash your hands. Check the strength, expiry, pen and solution against the leaflet’s checks.
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Attach a new needle
Swab the red seal. Attach a compatible needle. Keep its outer shield; discard the inner shield.
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Prime
Prime before every injection using the leaflet’s sequence. Confirm medicine appears at the needle tip.
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Choose your site
Use the thigh or abdomen, at least 5 cm from the navel. Another person can inject the upper arm. Rotate sites.
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Dial
Turn the knob fully until “1” appears. Do not count clicks to select a dose.
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Inject
Insert the needle. Press the knob fully and hold while slowly counting to five. Check “0” before withdrawing.
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If uncertain
Follow the leaflet’s incomplete-dose instructions. Do not redial or repeat the dose.
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Remove the needle
Carefully replace the outer shield, unscrew the needle into a sharps bin, then recap the pen.
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Store safely
Follow the leaflet’s storage limits. Discard after four doses or 30 days from first use, whichever comes first. Read how to store Mounjaro for guidance on refrigeration and expiry.
For a fuller illustrated explanation, see how to inject Mounjaro.
- Feeling sick (nausea)
- Diarrhoea
- Not feeling hungry
- Being sick (vomiting)
- Constipation
- Indigestion or an upset stomach
- Stomach pain
- Tiredness
- Redness, itching, or soreness where you injected
- Dizziness
- Heartburn or acid reflux
- Mounjaro hair loss and temporary thinning
- Gallstones (small stones in the gallbladder)
- Pancreatitis: severe, constant stomach pain that doesn't go away, sometimes spreading to your back — stop injecting and get help immediately
- Serious allergic reaction: swelling of your face, lips, or throat, difficulty breathing, or a spreading rash
- Kidney problems caused by severe dehydration from vomiting or diarrhoea
- Gallbladder problems: severe pain in the upper right side of your stomach, with fever or yellowing of the skin
For more detail, read our guide to Mounjaro side effects.
Mounjaro®, contraception and pregnancy
Important: Mounjaro may reduce protection from the contraceptive pill
If you take an oral contraceptive pill, use condoms in addition to your pill:
- For four weeks after starting Mounjaro.
- For four weeks after every dose increase.
Alternatively, discuss switching to a suitable non-oral contraceptive method, such as an implant or coil. Ask your clinician how to switch without a gap in protection.
For a fuller explanation of which methods are affected and when extra protection is advised, read our Mounjaro and the contraceptive pill guide.
Vomiting or severe diarrhoea can also reduce pill protection. Follow the instructions for your particular pill and ask a pharmacist or sexual health service if you are unsure.
How does this differ from Wegovy®?
Semaglutide does not carry the same recommendation for additional barrier contraception solely because treatment is started or increased. However, vomiting or severe diarrhoea can still affect the pill. Effective contraception remains important with either treatment.
Pregnancy, planning a pregnancy and breastfeeding
- Pregnancy: Mounjaro should not be used during pregnancy. If you think you may be pregnant, contact your prescriber promptly before taking another dose.
- Planning a pregnancy: stop Mounjaro at least one month before trying to conceive. Agree this with your prescriber and continue contraception during the waiting period.
- Breastfeeding: tell your prescriber before starting or continuing treatment. Current product information allows tirzepatide to be considered during breastfeeding following an individual assessment. However, Happy Pharmacy’s weight-management service does not prescribe during breastfeeding, as set out in our eligibility criteria above. Do not start or restart it without advice.
- Fertility: the effect of tirzepatide on human fertility is unknown. Mounjaro is not a fertility treatment or a contraceptive.
For broader evidence on treatment after 40, read our guide to Mounjaro benefits for women over 40. If menopause-related weight gain is your main concern, see our evidence-based guide to Mounjaro for menopause.
Further information: Mounjaro prescribing information and GLP-1 medicines and contraception: patient information.
| Source | Detail |
|---|---|
| SURPASS-1 | Rosenstock J et al. Effect of tirzepatide monotherapy on glycaemic control in adults with type 2 diabetes. Lancet. 2021;398(10295):143–155. |
| SURPASS-2 | Frías JP et al. Tirzepatide versus semaglutide once weekly in patients with type 2 diabetes. N Engl J Med. 2021;385(6):503–515. |
| SURMOUNT-1 | Jastreboff AM et al. Tirzepatide once weekly for the treatment of obesity. N Engl J Med. 2022;387(3):205–216. |
| Mounjaro® SmPC | Mounjaro® (tirzepatide) Summary of Product Characteristics. Eli Lilly and Company. Available at: electronic Medicines Compendium (emc). Last updated 2024. |
| NICE NG246 | National Institute for Health and Care Excellence. Obesity: identification, assessment and management. NICE guideline NG246. Published 2025. |
| NICE TA1026 | National Institute for Health and Care Excellence. Tirzepatide for managing overweight and obesity (TA1026). Published 2025. |
| NICE TA875 | National Institute for Health and Care Excellence. Semaglutide for managing overweight and obesity (TA875). Published 2023. |
| MHRA | Medicines and Healthcare products Regulatory Agency. Mounjaro® (tirzepatide) — MHRA approval for weight management. November 2023. |
Patient information
Official resources for Mounjaro use, safety, and guidance.
References
1. What Mounjaro (tirzepatide) is — official UK product information
• Summary of Product Characteristics (SmPC) – Mounjaro (tirzepatide) –
emc
• Patient Information Leaflet (PIL) – Mounjaro (tirzepatide) –
emc
2. How it’s used — manufacturer instructions
• Instructions for use / user manual – Mounjaro KwikPen – emc
3. Clinical effectiveness — weight loss outcomes from trials
• SURMOUNT-1 Trial – Tirzepatide once weekly for obesity (average weight-loss outcomes over ~72 weeks) –
NEJM
• SURMOUNT-1 Trial Registration –
ClinicalTrials.gov
• PubMed record (SURMOUNT-1) –
PubMed
4. Eligibility and access decisions — UK guidance context
• NICE Technology Appraisal (TA1026) – Tirzepatide for managing overweight and obesity – NICE
5. Safety and side effects — what to do and how to report
• Side effects, contraindications, warnings and precautions – SmPC (see section above) –
emc
• Yellow Card Scheme – what happens after you report –
MHRA Yellow Card
Medically Reviewed for Clinical Accuracy
Authored by:
Palvinder DeolSuperintendent Pharmacist (MPharm, MRPharmS, GPhC Registered)
Over 25 years’ clinical experience in UK community pharmacy and medicines optimisation.
Reviewed by:
Nigel HowardIndependent Prescriber (MPharm, GPhC Registered)
Over 20 years’ clinical experience in prescribing and patient-facing pharmacy services.
GPhC Inspection Result
Inspection Outcome: All Standards Met ✅
Our digital-first pharmacy achieved rare “Good Practice” recognition during our GPhC inspection on 19 May 2025, showcasing our commitment to safe, high-quality and innovative online healthcare.
View full inspection report →GPhC Registration No. 9013192 | Inspected 19 May 2025
Frequently asked questions
Can you buy Mounjaro online in the UK?
You can buy Mounjaro online from Happy Pharmacy following an online consultation and approval by a UK-registered prescriber. Your medical history and current medicines are assessed to determine whether treatment is suitable. Completing the consultation does not guarantee a prescription.
How much does Mounjaro cost per month in the UK?
The cost of Mounjaro depends on your prescribed strength and whether you choose a single purchase or subscription. Select your dose in the ordering box above to compare the current prices.
Why does the price of Mounjaro increase at higher doses?
Higher strengths of Mounjaro cost more because they contain a larger amount of the active ingredient tirzepatide. Dose increases are only made if clinically appropriate, so not everyone progresses to the highest strength.
Do I pay for a consultation separately?
No. Your online consultation and prescriber review are included, with no separate consultation fee. Treatment is supplied only if clinically appropriate. Delivery charges are shown at checkout.
How often do I need to reorder Mounjaro?
Each KwikPen contains four weekly doses. Arrange your next supply before your pen runs out, allowing time for clinical review and delivery. Repeat prescriptions and dose changes require prescriber approval. If you have taken a break, contact our team before restarting.
Can I stay on a lower dose to reduce cost?
You do not necessarily need the highest dose. The recommended adult maintenance doses are 5 mg, 10 mg and 15 mg once weekly; 2.5 mg is the starting dose, while 7.5 mg and 12.5 mg are intermediate steps. Your prescriber chooses the dose based on response and tolerability. Discuss affordability with the team, but do not change your dose yourself.
Is it safe to buy Mounjaro online in the UK?
Mounjaro is a prescription-only medicine and should only be supplied by a UK GPhC-registered pharmacy following a medical assessment. Always ensure the provider requires a consultation before prescribing.
Do I need a prescription for Mounjaro®?
Yes, Mounjaro® is a prescription-only medication. The supply of Mounjaro is only made if it is safe and appropriate, following an online assessment by one of our clinical team.
Is Mounjaro available on the NHS?
Yes, but access is limited and subject to strict eligibility criteria, local NHS funding, and referral pathways. Read our guide to NHS weight loss injection eligibility for the current routes and criteria.
Can I get Mounjaro without seeing a GP?
Yes. A UK-registered online pharmacy such as Happy Pharmacy can assess you and issue a prescription without an in-person GP appointment.
What is Mounjaro® used for?
Mounjaro® is primarily used in the NHS to manage type 2 diabetes and to aid weight loss in individuals with obesity or overweight with certain conditions.
Is Mounjaro approved for weight loss?
Yes, Mounjaro is now approved for weight loss in the UK for eligible patients. It was initially licensed for diabetes but is now authorised and licensed for weight loss management.
How much weight can I lose with Mounjaro®?
In SURMOUNT-1, adults with obesity or overweight with a weight-related complication, without diabetes, lost an average of 20.9% of their starting body weight in the 15 mg group at 72 weeks, compared with 3.1% with placebo. These figures use the treatment-regimen analysis and include support with diet and physical activity. Individual results vary and are not guaranteed; see the clinical evidence section above.
How long does Mounjaro take to start working?
There is no fixed timeline. Some people notice appetite changes early, while others take longer, and weight change can be uneven. Your prescriber reviews your response and side effects before deciding whether to continue or increase your dose. An increase is not automatic.
How long do I have to stay on Mounjaro?
Mounjaro is a long-term weight loss treatment. The duration depends on your weight loss goals, progress, and how well you tolerate the medication. Many patients stay on Mounjaro for 6–12 months or longer under medical supervision.
What happens when you stop taking Mounjaro?
Weight regain is possible if lifestyle changes are not maintained after stopping Mounjaro. To help maintain results, continue with healthy eating, regular exercise, and follow-up care with your doctor or pharmacist.
Read our guide on what happens when you stop taking mounjaro for further information.
Why am I not losing weight on Mounjaro?
Weight loss varies. If you’re not seeing results, review your diet, activity levels, and consistency. It may also be time to adjust your dosage. Speak to your online Happy Pharmacy Team.
Why do I still feel hungry on Mounjaro?
It’s common to still feel hungry on Mounjaro, especially in the early stages or at lower doses. Appetite suppression builds gradually, and factors such as diet, sleep, and hydration can also affect how full you feel during treatment. You can learn more about this in our guide on why do I still feel hungry on Mounjaro.
How long does Mounjaro delivery take?
After your consultation is approved and a prescription issued, orders are typically dispatched within one working day. Arrival depends on the delivery service and your location; next-day delivery is not guaranteed. See our delivery policy for available services and charges.
Is Mounjaro delivered in temperature-controlled packaging?
Yes. Mounjaro is shipped in temperature-controlled packaging to keep it within the required storage range during delivery.
How should I store Mounjaro®?
Before first use, refrigerate Mounjaro KwikPen at 2–8°C. Do not freeze or use a pen that has been frozen. Keep it protected from light and follow the leaflet supplied with your pen.
After first use, the pen may be kept unrefrigerated for up to 30 days at a temperature not above 30°C. Discard it after four doses or 30 days from first use, whichever comes first, even if medicine remains. Remove the needle after every injection and replace the cap.
Use a sharps bin for used needles. A sharps bin is included with your first order; additional bins can be purchased. Ask your pharmacist or local council about safe disposal. Read our guide to storing Mounjaro.
How long can Mounjaro be out of the fridge?
After first use, Mounjaro KwikPen may be stored unrefrigerated for up to 30 days at a temperature not above 30°C. Before first use, keep it refrigerated at 2–8°C. If an unused pen has been left out of the fridge, exposed to heat or frozen, contact your pharmacist before using it. Discard a pen after four doses or 30 days from first use, whichever comes first.
Can you lose weight on Mounjaro without exercise?
Yes, some people can lose weight on Mounjaro without structured exercise. The medication reduces appetite and increases feelings of fullness, which can lower calorie intake naturally. However, adding physical activity may improve long-term results and overall health. For more detail, read our guide on losing weight without exercise on Mounjaro.
Can I drink alcohol while taking Mounjaro?
Alcohol is not listed as a contraindication or named interaction in the current UK product information. However, it may worsen nausea, vomiting, diarrhoea or dehydration, and low blood sugar needs extra care if you also use insulin or a sulphonylurea. Read our guide to alcohol while taking Mounjaro for the UK 14-unit guideline and practical precautions.
What foods should I avoid on Mounjaro?
Avoid high-fat, greasy, or sugary foods that can worsen nausea. Eat smaller meals and avoid alcohol when possible, especially early in treatment. For practical meal ideas, see our guide to what to eat on Mounjaro.
What if I miss a dose of Mounjaro?
If you miss a dose, take it as soon as possible within four days (96 hours) of when it was due. If more than four days have passed, skip it and take your next dose on your usual day. Leave at least three days (72 hours) between injections, and never take a double dose to make up for one you missed.
If you have missed several doses or taken a treatment break, contact your prescriber before restarting; your dose may need to change. Read our missed Mounjaro dose guide.
Can I travel with Mounjaro?
Yes, you can travel with Mounjaro. As a prescription medication, it is allowed in hand luggage when flying and can be taken abroad, provided it is stored correctly and clearly labelled.
If you’re taking the contraceptive pill, can you use Mounjaro?
Mounjaro can affect oral contraceptive effectiveness. Use condoms alongside your pill for four weeks after starting treatment and for four weeks after every dose increase, or discuss a suitable non-oral contraceptive method with your prescriber.
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