Over 20 answers to common questions for UK users of Mounjaro for weight loss. Straight to the point!

Are Mounjaro pens single use?

No. Each Mounjaro pen contains four doses. You use one dose per week using the separate needle provided.

After the fourth dose, you throw the pen away. Do not reuse a pen or share it with anyone else.

Can Mounjaro cause diarrhea?

Yes. Diarrhoea is a common side effect, especially when starting or increasing your dose.

This happens because Mounjaro slows down how quickly your stomach empties.

Drink plenty of water. If it’s severe or lasts more than a few days, talk to your doctor or pharmacist.

Can Mounjaro cause dizziness?

Yes. Dizziness can occur, often due to low blood sugar (especially if you also take insulin or certain diabetes tablets), dehydration from sickness or diarrhoea, or simply as a side effect of the medicine.

Dizziness affects ~1 in 10 users. Common causes include:

• Low blood sugar (if combined with insulin/sulfonylureas).
• Dehydration from nausea/diarrhoea.
  Action:
• Check blood sugar if diabetic.
• Drink water regularly; avoid sudden standing.
• If you feel dizzy, sit down until it passes. Tell your doctor if it happens often.
• If severe or with chest pain, contact your GP or NHS 111.

Can Mounjaro make you tired?

Yes, some users feel tired, especially when starting or increasing doses.

This is often due to reduced calorie intake or your body adjusting to the medication. Fatigue usually improves within weeks. To manage it:

• Prioritise 7–9 hours of sleep nightly.
• Eat balanced meals with lean protein and whole grains.
• Stay hydrated; aim for 6–8 glasses of water daily.

Can Mounjaro cause hair loss?

Hair loss isn’t a common direct side effect.

 Significant weight loss itself can sometimes cause temporary hair thinning. If you notice hair loss while using Mounjaro, discuss it with your doctor.

Can you drink alcohol on Mounjaro?

Be cautious. Alcohol can worsen common Mounjaro side effects like feeling sick or dizzy.

It can also affect your blood sugar levels. If you choose to drink, do so in moderation and be aware of how it affects you.

Avoid sugary alcoholic drinks.

Can you lose weight on Mounjaro?

Yes. Mounjaro (tirzepatide) is licensed in the UK to help adults with obesity (BMI 30+) or overweight (BMI 27+) with weight-related health problems lose weight, alongside a reduced-calorie diet and increased exercise.

• In the UK, you may get Mounjaro privately or on the NHS. Prescribing of Mounjaro on the NHS formally started in June 2025.
  • The roll out into the UK population is in phases; the patients with greatest needs receive higher priority.
  • Hence the first year targets individuals with BMI 40 (or more) and 4 or more weight related health conditions, and people of minority ethnic background with BMI >37.5, and weight related conditions.

How much weight loss on Mounjaro?

Studies show significant weight loss. People using the highest dose (15mg weekly) lost around 20-25% of their starting body weight on average after about 18 months when combined with diet and exercise. Results vary per person.

Is Mounjaro insulin?

No. Mounjaro (tirzepatide) is not insulin. It’s a different type of medicine called a GLP-1 and GIP receptor agonist. These behave like two hormones in the body that manage blood sugar and appetite in several ways.

Is Mounjaro used for weight loss?

Yes. Mounjaro is licensed in the UK specifically for weight management in adults with obesity or overweight with related health conditions, used alongside diet and exercise changes.

It is also used for type 2 diabetes.

What is the cost of Mounjaro?

Costs vary. As a private prescription in the UK, prices start around £220-£270 per box (containing one 4-dose pen). The exact price depends on the dose strength (2.5mg, 5mg, 7mg, 10mg, 12.5mg, 15mg) and the pharmacy. It is not routinely available on the NHS for weight loss.
*Source: Major UK Online Pharmacy Pricing (e.g., Chemist4U, Simple Online Pharmacy – July 2025)*

If Mounjaro gets warm?

Unopened pens: Keep refrigerated (2°C to 8°C). You can store an unopened pen at room temperature (up to 30°C) for up to 21 days if needed (e.g., when travelling). Throw it away after 21 days out of the fridge. In-use pens: Store your current pen at room temperature (below 30°C) and use it within 21 days.

If Mounjaro freezes, is it still good?

No. Do not use it. Never freeze Mounjaro. Freezing damages the medicine. If a pen has frozen, even if it thaws, it will not work properly. Throw it away safely.

Are Mounjaro and Zepbound the same medication?

Yes. Mounjaro and Zepbound both contain the exact same active medicine, tirzepatide. Zepbound is simply the brand name used for tirzepatide when it’s prescribed specifically for weight loss in some countries like the US. In the UK, it’s only called Mounjaro, whether used for diabetes or weight loss.

How safe is Mounjaro?

Mounjaro is generally safe when prescribed and monitored by your doctor. Common side effects include feeling sick, diarrhoea, and constipation, which often improve over time. Serious side effects (like pancreatitis or thyroid problems) are rare but possible. Tell your doctor about all your health conditions before starting.

Can I use Mounjaro when pregnant?

No. Mounjaro is not recommended during pregnancy or breastfeeding. Animal studies suggest potential risks, and human safety data is lacking. If planning pregnancy:

• Stop Mounjaro ≥2 months before trying to conceive.
• Switch to a pregnancy-safe alternative like metformin if needed for diabetes.

When is the best time to take Mounjaro?

Any consistent day/time weekly, with or without food. Key tips:

• Choose a day you’ll remember (e.g., Monday mornings).
• If changing days, wait ≥3 days (72 hours) between doses.
• Store unused pens refrigerated (2°C–8°C); in-use pens may last 21 days at room temperature (≤30°C), but best kept in the fridge.

If Mounjaro doesn’t work?

Talk to your doctor. Weight loss can vary. If you haven’t lost enough weight after several months on the highest tolerated dose, Mounjaro might not be the right medicine for you. Your doctor can discuss other weight management options.

Mounjaro injection sites?

Use these areas only:

• Stomach (5 cm away from your belly button).
• Thigh (front area, not near joints).
• Back of upper arm (if someone else injects you).
  Rotate sites weekly to avoid lumps. Never inject into muscle, scars, or moles.

Mounjaro dosage chart

Never self-adjust your dose. Your doctor decides increases based on tolerance and weight loss.

More Reading

• Mounjaro for Menopause Weight Gain: Help for Belly Fat and Fatigue?
• Mounjaro vs Wegovy UK: How to Choose the Best Weight Loss Injection
• How to Buy Mounjaro Privately in the UK
• Understanding A Lump in the Vaginal Area: Causes and Treatments
• Unlocking the Secrets of Weight Loss: 4 Science Backed Strategies for Your Success

Editing by AskAwayHealth Team

Disclaimer

All AskAwayHealth articles are written by practising Medical Practitioners on various healthcare conditions to promote quality healthcare. 

The advice in our material is not meant to replace a qualified healthcare practitioner’s management of your specific condition.
Don’t hesitate to contact a health practitioner to discuss your condition or reach us directly here.

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