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Mounjaro® Injectable Pen

Effective GLP-1 weight loss treatment

45,000+ service reviews
  • Lose up to 20% body weight
  • Weekly self-injection pens
  • Supports healthy weight loss by reducing appetite and making you feel fuller
  • No subscriptions

Real results with
MedExpress

Kirsten before
Before
Kirsten after
After

Management of my appetite was the biggest challenge, so the medication has really just been game-changing. I’ve been trying to lose weight for 14 years. As soon as I knew about this medication from my research, I ordered it the same night I found out it was available.

Chloe J after 2 months
George before
Before
George after
After

Management of my appetite was the biggest challenge, so the medication has really just been game-changing. I’ve been trying to lose weight for 14 years. As soon as I knew about this medication from my research, I ordered it the same night I found out it was available.

Chloe J after 2 months

Weight loss that’s 6× more effective

Illustration of weight loss using GLP-1 injectable treatments showing it is 6 times more effective than diet alone

Mounjaro® information

Mounjaro® KwikPen (tirzepatide) is an innovative injectable weight loss drug. It mimics natural GLP-1 and GIP hormones in your gut, helping you control your appetite and making you feel fuller for longer. When paired with a reduced-calorie diet and increased physical activity, it results in effective, healthy weight loss.
Mounjaro® is an injectable medication that comes in a pre-filled pen. It needs to be used once weekly, on the same day. The pen itself is simple to use and the needles are very small, so it’s relatively pain-free and easy to get used to.
Mounjaro® can be injected in the abdomen, thigh or upper arm at any time during the day, with or without food. It’s recommended that you use it around the same time each week — this will regulate the medication’s effectiveness.
You’ll receive clear instructions with your first order on the specifics for applying your treatment confidently. Our team are also on hand to answer any questions.
Mounjaro® (tirzepatide) is an injectable weight loss drug for people with a BMI over 30. For individuals with weight related health concerns, they may be eligible with a BMI over 27. These related concerns include high blood pressure, diabetes, heart disease and raised cholesterol.
If you have Type 2 diabetes and a BMI less than 27, we can’t prescribe you Mounjaro® for weight loss.
Your treatment starts at a low dose and then increases every four weeks. When you first start using Mounjaro®, the starting dose is 2.5 mg, once a week, for four weeks. The dose will then be increased after every four weeks until you reach the recommended dose of 15 mg a week.
This chart shows how your dosage will increase over five months:
Mounjaro® dosage guide
The clinical team will review your weight with every order to ensure this product is working for you. This way we can ensure the dose which you peak at is optimal for you. At this peak, for us to continue prescribing Mounjaro® to you, you’ll need to have lost around 5% of your initial body weight after a period of time.
Mounjaro® is one of the most effective weight loss treatments available. On average, people lose 20.9% body weight over 36 weeks and 25.3% body weight over 88 weeks.
In a study of people with type 2 diabetes on metformin, the active ingredient in Mounjaro® was shown to be twice as effective as Wegovy®.
When you order Mounjaro® for the first time, you’ll receive 1 pen that includes each of your 4 doses for your first 28 days of treatment. It’s important to store it in a refrigerator between 2-8°C. Mounjaro® comes in a single-dose pen that requires no mixing. You’ll also receive:
  • A sharps bin with your first order
  • 4 needles (One to use for every time you inject)
  • Swabs to clean your skin before injecting
  • An instruction leaflet
  • Extra tips to help you lose weight
With each new order, you’ll receive your next pen at the right strength for you.
When you’ve been using Mounjaro® for 3 weeks, it’s time to think about ordering your next pen from us. At this time, we’ll send you a reminder to log on and complete a weight loss consultation.
If you’re responding well to treatment, at the next order you can increase your dose. We’ll then send you an additional pen in a temperature-controlled delivery packaging. It’s important to store these in a refrigerator between 2–8°C. This pack will last you 28 days. After you finish your 3rd pen, remember to return to MedExpress to reorder supplies so you can continue treatment uninterrupted.
The clinical team will review your weight with every order to ensure this product is working for you. When you’ve used your highest tolerated dose for 6 months, we’ll review your progress. For us to continue prescribing Mounjaro® to you, you’ll need to have lost around 5% of your initial body weight.
Your health and wellbeing are our top priority, so please reach out to the MedExpress clinical team if you have any concerns while taking Mounjaro.
You’ll receive a sharps bin with your first order. This is a special waste bin that’s used to store sharps material, like needles, until it can be safely disposed of.
After every use, dispose of the needle into the sharps bin. After the 4 doses, and once the needle has been removed, the pen can be disposed of in your household waste or the sharps bin. When full, your sharps bin can be collected for disposal by your local council.
Once you’ve started treatment, you’ll be able to purchase more sharps bins with new orders.
Mounjaro® can be kept unrefrigerated for up to 30 days. However, we recommend you return the pen to the fridge after each use.
We’re here to support you throughout your weight loss journey, offering tips to help you manage side effects and providing reassurance if you have any concerns.
While Mounjaro has helped many people reach their health goals, it’s crucial to understand what to watch for along the way. Below, we’ve outlined the most common and rare side effects, along with guidance on when to seek help.

Very common

These side effects may occur in more than 1 in 10 people and usually go away over time. They are most common when first starting Mounjaro and when increasing the dose.
  • Examples: feeling sick (nausea), vomiting, diarrhoea, stomach pain, constipation.

Common

These side effects may occur in up to 1 in 10 people.
  • Examples: dizziness, a reduction in blood pressure, indigestion, heartburn, bloating, burping, flatulence, fatigue, injection site reactions (redness, swelling), gallstones, allergic reaction (e.g, rash, itching, and eczema), low blood pressure, hair loss.

Uncommon

These side effects may occur in up to 1 in 100 people.
  • Examples: Injection site pain, changed sense of taste, increased heart rate.
  • SERIOUS: acute pancreatitis. This is inflammation of the pancreas that can cause severe stomach pain which can radiate to your back that doesn’t go away. Most patients feel very ill with pancreatitis and may present with severe vomiting (i.e., vomiting 3 times or more in one day, or having coffee ground or blood in the vomit). You should call 999 or attend A&E right away if you experience these symptoms.
  • SERIOUS: acute gallbladder disease. This is inflammation of the gallbladder (also known as cholecystitis) that can cause a sudden sharp pain in the upper right side of your stomach that radiates towards your right shoulder. The affected area of the stomach will feel very tender and deep breathing can make the pain worse. You should call 999 or attend A&E right away if you experience these symptoms.

Rare

These side effects may occur in up to 1 in 1000 people.
  • SERIOUS: severe allergic reaction (anaphylaxis). This can present as difficulty breathing, swelling of lips, tongue and/or throat, difficulty swallowing, rapid heartbeat. You should call 999 or attend A&E right away if you experience these symptoms.
If you have any questions about side effects or how to manage them, we’re here to support you.

Mounjaro® facts

  • Treatment type
    GLP-1 + GIP injectable pen
  • Weight loss in 9 months
    Average 20.9% body weight
  • Weight loss in 20 months
    Average 25.3% of body weight
  • Available strengths
    2.5mg – 15mg
  • Active ingredient
    Tirzepatide
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How it works

  1. Step 1 illustration

    1. Answer quick questions

    No GP or pharmacy visits, just a quick online consultation.

  2. Step 2 illustration

    2. Choose a GLP-1 treatment

    Select from our recommended UK-licensed weight loss injectables.

  3. Step 3 illustration

    3. Get it delivered direct

    Your treatment arrives in discreet packaging, direct to your door.

Find a treatment

Mounjaro® FAQs

Mounjaro® is a once-weekly injection that’s given in the arm, leg or abdomen. It uses a very small, fine needle for a near-painless injection just below the surface of the skin. The Mounjaro® pen comes with clear instructions for use. It has a simple dial in order to deliver the right amount of medication for your treatment stage. Once you’ve had the injection, remove and dispose of the needle in a sharps bin. Replace the cap and store as instructed.
Each Mounjaro® pen contains 4 dosages. Given this is a weekly dosage, one pen lasts 4 weeks. The needles should be disposed of after each administration.
The strength of the injection is increased every 4 weeks until the highest tolerated dose, or the maximum dose is reached.
The clinical team will review your weight with every order to ensure this product is working for you. When you have used your highest tolerated dose for 6 months, we will review your progress. For us to continue prescribing Mounjaro® to you, you’ll need to have lost around 5% of your initial body weight. You are likely to be able to continue using it for up to two years with clinical guidance.
The clinical team will review your weight with every order to ensure this product is working for you. When you have used your highest tolerated dose for 6 months, we will review your progress. For us to continue prescribing Mounjaro® to you, you’ll need to have lost around 5% of your initial body weight.
If you have any queries or concerns at any time, you can contact our support team
If you experience symptoms such as persistent nausea, vomiting and diarrhoea with your current Mounjaro® dose, speak to our customer care team for advice. We may recommend continuing or decreasing your dose to see if that helps improve your tolerance.
We can also give you tips to help manage any symptoms and get maximum benefit from the medication. It’s important to not increase your Mounjaro® dose until your body is ready, so make sure you contact MedExpress if you have persistent side effects.
If you are concerned or alarmed by your symptoms review the patient information leaflet or seek medical attention
Yes, Mounjaro® KwikPen is licensed for weight loss in the UK.
Mounjaro® should be stored in a refrigerator and kept at 2–8°C, or in a cooler/ice pack when travelling. Don’t freeze it, or use it if it has been frozen. Keep the cap on when the pen isn’t in use to protect it from light.
If a dose is missed, it should be administered as soon as possible, within 4 days after the missed dose. If more than 4 days have passed, skip the missed dose and administer the next dose on the regularly scheduled day. In each case, patients can then resume their regular once weekly dosing schedule.
Mounjaro should not be used during pregnancy.
If you are of childbearing age and sexually active, you should use contraception while taking Mounjaro.
As Mounjaro may reduce the effectiveness of your oral contraceptive pill, you must use an additional barrier form of contraception, such as condoms, or switch to a non-oral method such as an IUD or implant.
Recent research has shown that Mounjaro may reduce the effectiveness of your oral contraceptive pill. This could increase the risk of an unplanned pregnancy.
To stay protected, you must use an additional barrier form of contraception, such as condoms, or switch to a non-oral method such as an IUD or implant while using Mounjaro.
If you experience severe diarrhoea that lasts for over 24 hours, or vomiting within three hours of taking your oral contraceptive pill, you may need a repeat dose of your oral contraceptive pill. Contact your GP or call 111 for medical advice if this occurs.
If you experience persistent vomiting or diarrhoea, consider a non-oral method of contraception. Contact your GP to discuss your options.
If you are planning on becoming pregnant, it is recommended that you wait at least one month before your last dose of Mounjaro before trying.
If you are planning to become pregnant, it is recommended that you wait at least one month after your last dose of Mounjaro before trying.
No, we advise patients to not use Mounjaro while breastfeeding. It is not yet known whether Mounjaro passes into breast milk, so the risk to a breast fed baby can’t be ruled out.
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Backed by our experienced UK-based medical team

Dr Catriona Maybury picture

Dr Catriona Maybury

Medical Director | MBChB, MRCP, PhD

GMC: 6130975

Declan Lismore picture

Declan Lismore

Superintendent Pharmacist | MPharm, MRPharmS, MPSI, PGDip

GPhC: 2073498

Dr Paul Davis picture

Dr Paul Davis

Senior GP and Medical Lead | BSc MB BS DCH MRCGP

Dr Safia Hussain picture

Dr Safia Hussain

GP Lead | MBBS, BSc, MRCGP, DRCOG, PGDip Clinical Dermatology

Mounjaro® prices

Treatment begins with a low starting dose, which may be gradually increased every four weeks based on your progress.

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Authored by Dr Clare Morrison. Last reviewed 01 February 2025 by Liyya Patel and Siobhan Titre.