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Mounjaro® Injectable Pen

Effective GLP-1 weight loss treatment

85,000+ service reviews

Lose an average of 22.5% of your body weight in 72 weeks (1 year, 5 months)*

Once-weekly self-injection pen

Helps quiet food noise by mimicking hormones that regulate appetite and fullness

No subscriptions

£999.99

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Check your eligibility

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The right dose when you need it

Once you've downloaded the app and subscribed to the SemaPen medication programme, we'll quickly send you the right Mounjaro pens when you need them. You'll also get a sharps bin to dispose of needles safely.

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Personalised, professional support

Choose a care plan to personalise the support you receive. Get expert help to lose weight safely and steadily, from smart health tracking to face-to-face video consultations with specialist dietitians.

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Fast, discreet delivery

You can share your success when you're ready. That's why your Mounjaro weight loss injections come directly to your door in discreet packaging.

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Money-back guarantee

That's right. If you don't achieve at least 5% weight loss after you purchase Mounjaro online and complete the programme, we'll provide a refund.*

Taking Mounjaro: a step-by-step guide

1. Prepare and inspect

Wash your hands thoroughly. Pull the cap off the Mounjaro pen and inspect the medication. Don't use it if it's expired, has the wrong dosage or looks discoloured or cloudy.

2. Attach the needle

Wipe the pen's inner seal with a swab. Select a new needle, remove the paper tab and screw it onto the pen. Pull off the inner and outer shields to reveal the needle.

3. Check the flow

Dial the pen until it reaches the prime position (marked by an extended line). Hold the pen upright, give it a few taps and push the dose knob until you see liquid squirt out.

4. Prepare your dose

Turn the dial until you see the number 1 in the window. This indicates one full dose. The dial should stop here.

5. Inject the needle

Take your Mounjaro injection by inserting the needle into the soft part of your belly or thigh. Push the dose knob and hold it down for 5 seconds.

6. Wait a week and repeat

Each Mounjaro pen contains enough medication for 4 doses (one per week for a month). It's a good idea to rotate injection sites with each weekly dose.

How the SemaPen medication programme works

Thanks to our advanced Semapen app and expert advice, weight loss just got a whole lot simpler.

Here's the thing. Online pharmacies often sell you medication and leave you to figure things out on your own.


But Semapen is different. As soon as you subscribe to the SemaPen medication programme, you'll unlock all the professional and practical support you need to lose weight and improve your health. Our aim? To give you the best chance of long-term success.


This means automatic delivery of each new dose. It means daily support through our app and personalised weight loss guidance  from real experts. And it means no in-person appointments, pharmacy visits or restrictive fad diets.


It's weight loss made simple. Finally.

What to expect

Signposts for success

It's weight loss with a clear way forward. When you subscribe to the SemaPen programme, you're joining a guided weight loss plan designed by UK obesity experts. Plus, you'll get access to our revolutionary app and support plans to help keep you on track.

Internet-enabled smart scale

Say 'no' to tedious updates and check-ins. You'll receive a £60 Withings® Body scale that sends updates to the app in real time. That means you and your team can track your journey together through your health dashboard. Easy.

Peace of mind

You're free to cancel your subscription at any time.***** And if you don't lose at least 5% of your body weight, you'll get your money back.*

The Semapen app

Get onboarded onto our app for quick approval if eligible – and take advantage of all the expertise and support you need to lose weight and live healthier. Manage your programme, track your weight and health, learn good habits with Semapen Academy and more.

Mounjaro dosage chart

You should take Mounjaro injections for weight loss once per week. You must take the medication on the same day each week. However, you can take it at any time of day, and you don't need to take it with meals.


The starting dose is 2.5mg per week. After your first month, we'll send you a new pen with a 5mg dose. The dose increases each month until it reaches 15mg from month six onwards.


It's important to increase the dose gradually because it takes time for your body to adjust to the medication. But don't worry about remembering to order the right dose. Subscribe to our Mounjaro programme and we'll automatically send you the right pen at the right time.

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A purple and white bottle of mounjaro insulin
A mountaro 7.5 ml syringe with a purple cap
A purple and white mountaro pen with a purple cap
A white and purple mountaro pen with a purple cap
A white and purple pen with the word mounjaro on it

What are the possible side effects?

Like all medications, Mounjaro can cause unwanted reactions or side effects.


The most common side effects experienced by Mounjaro patients are nausea and stomach upsets, including diarrhoea, vomiting and tummy pain. These side effects are fairly common but tend to happen less with Mounjaro than Wegovy.


For most patients, the side effects aren't too bad and can be treated effectively with home remedies. Many find they get less pronounced as they continue the treatment, too. However, they often get worse for a time when patients step up to a higher dose.


Mounjaro is also known to make the oral contraceptive pill work less effectively. If you currently take the contraceptive pill, you should change to an alternative form of contraception while using Mounjaro.


You may have heard of people experiencing hair loss or hair thinning while using Mounjaro. This affects a minority of patients but is actually caused by rapid weight loss, not by the medication itself. For most people, the hair thinning or loss gets better as they continue the treatment.


You should also be cautious of online platforms that offer Mounjaro for sale but lack credentials or do not require consultations. These platforms may be selling unsafe products.


This is not an exhaustive list of side effects. For more information, read our guide to the side effects of weight loss drugs.

Meet your experts

Semapen is part of Phoenix Health, the only private bariatric provider trusted to provide NHS treatment. Meet the experts who work for your success.

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