Mounjaro

What is Mounjaro and how does it work?

Mounjaro is a prescription-only weight loss injection containing the active ingredient tirzepatide. You self-inject once a week, with each pen prefilled with four doses. That means one pen should last you four weeks.

Mounjaro works by mimicking two natural hormones in your body: GLP-1 and GIP. Similar weight loss treatments only mimic GLP-1, so Mounjaro's dual-action is often linked to stronger results.

This dual-action effect helps you lose weight by:

• lowering your appetite
• reducing cravings
• slowing digestion to keep you fuller for longer
• helping your body manage sugar from food more effectively, which can reduce energy crashes and snacking between meals

However, Mounjaro works best when paired with lifestyle changes, like eating a balanced diet, staying active, and building habits you can stick with long-term.

How long does Mounjaro take to work?

Mounjaro starts working from your very first dose, so you may notice your appetite and cravings easing within the first week. It’s normal, though, if it takes you a few weeks to feel the full effect.

You might not see much change on the scales in month one, however. Bigger changes tend to show up as you keep going with your treatment and increase your doses at a pace that works for you.

How much weight can you lose with Mounjaro?

On average, people lose around 22.5% of their body weight on Mounjaro. To put that into perspective, if you weighed 100kg (approx. 16 stone), you could lose 22.5kg (3.5 stone) in just under a year and a half (72 weeks).

But that's just an average. Your own results will depend on things like your starting weight and how closely you stick to your diet and exercise plan.

How long do you need to take Mounjaro?

"There's no fixed length of time. Many people stay on Mounjaro long-term to help maintain their results, while others choose to stop once they reach their goal weight. It's a very personalised plan.

"Weight loss isn't just about the number on the scales. Rather, it's about building habits that last. How long you stay on Mounjaro really depends on you, your goals, and how your body responds.

"We're here to support you at every stage, whether that's a few months or a few years."

Dr Rashi Malhotra, General Practitioner

Mounjaro eligibility

Mounjaro is suitable for people with a BMI of 30 or over, or a BMI of 27 or over alongside a weight-related condition like high blood pressure, high cholesterol, or prediabetes.

To get started, you'll complete a short online consultation, answering a few questions about your health and medical history. One of our clinicians will then review this to check if Mounjaro is safe and suitable for you.

Finding the right Mounjaro dose

Everyone starts on the lowest dose of 2.5mg to give your body time to adjust safely.

After that, your journey is your own. You'll gradually step up at a pace that suits you, spending at least four weeks on each dose, until you reach your maintenance dose. This might be 15mg, or it might be a lower dose – whatever gets you the best results with the fewest side effects.

You can see an example Mounjaro dosing schedule in the image below:

What to do if you miss a dose

• Less than four days late: Take it now and carry on as normal.
• More than four days late: Skip it and take your next dose on your usual day.
• More than two weeks late: Speak to your prescriber before continuing.

Never take two doses together to make up for a missed one.

Thousands of patients, real results

Sophie lost four stone in nine months on Mounjaro:

“I’m a lot happier in myself, which reflects on other people around me. I have a lot more confidence and can happily buy clothes and feel good in them.”

Baylee lost over nine stone, going from 20 stone to 11 stone:

“Mounjaro has been amazing. I’ve had minimal side effects, and it’s been a lifesaver for the symptoms of my pre-existing medical conditions. I’d recommend this to anyone who’s struggling to lose weight.”

Richard lost over two stone, alongside improvements to his blood pressure and cholesterol:

“I’ve lost over two stone and feel stronger and healthier. Mounjaro has given me peace of mind, knowing that a healthy weight is achievable.”

See more of what's possible with Mounjaro.

Your first Mounjaro order

You can only get Mounjaro once a clinician has reviewed your consultation and issued a prescription. Once you're approved, we'll get your order ready for fast, discreet delivery straight to your door.

With your first order, you'll receive:

• your Mounjaro pen, prefilled with your prescribed dose
• four single-use needles, so there's nothing extra to buy
• a sharps bin
• the patient information leaflet
• a welcome pack with full instructions

You'll also get free ongoing support from our clinicians throughout your journey, plus reorder reminders and guides to help you get the most from your treatment, all at no extra cost.

How to inject Mounjaro

Mounjaro is injected once a week, either by yourself or with someone's help. The KwikPen is designed to make this simple, and full instructions come with every order.

Here are eight simple steps for how to inject Mounjaro:

1. 1. Check your pen.
2. 2. Wash your hands.
3. 3. Attach a new needle.
4. 4. Prime the pen.
5. 5. Choose your injection site.
6. 6. Inject yourself.
7. 7. Remove the needle.
8. 8. Dispose of the needle.

Read our step-by-step guide on how to inject Mounjaro for the full walkthrough, or watch our video below. 

Where to inject Mounjaro

You can inject Mounjaro into your:

• abdomen
• upper arm
• thigh

If you want to inject in your upper arm, you'll need to get someone else to do it for you.

Storing your Mounjaro pens

• When it arrives: Pop unopened pens straight in the fridge, between 2°C-8°C.
• Once opened: You can keep a pen at room temperature for up to 30 days.
• If it overheats or freezes: Don't use it and dispose of it safely instead.

If you're travelling with Mounjaro, take your pens in hand luggage rather than packing them in the hold, since temperatures there can fluctuate. If you're travelling to a hot climate, use a cooling case to keep it at the right temperature.

It's a good idea to travel with the box your treatment originally came in. This will have your prescription attached, which is useful in case anyone needs to check it against your passport. 

It's also worth checking your destination's rules on bringing medication with you.

Read our full guide on travelling with Mounjaro for further details.

Disposing of your Mounjaro pens

Needles must be disposed of in a sharps bin. Once the needle's removed, the pen itself can be recycled. Sharps bins can be collected by your local council once they're full.

Potential Mounjaro side effects

You may encounter some side effects when using Mounjaro, though not everyone experiences them. Side effects tend to happen when starting treatment or increasing your dose.

Very common side effects may include:

• nausea
• vomiting
• diarrhoea
• constipation
• stomach pain

Common side effects may include:

• mild reactions where you inject, like rashes, bruising, or swelling
• indigestion
• quick pulse
• bloating
• wind and belching
• tiredness
• dizziness
• hair loss

Uncommon side effects may include:

• gallstones
• injection-site pain
• taste changes

For more information, read our full guide to Mounjaro side effects.

How long do side effects last?

Most side effects settle within a few days or weeks as your body adjusts. However, side effects may briefly return after you increase your dose.

How can I manage my side effects?

You can manage most Mounjaro side effects by:

• staying hydrated
• eating smaller, regular meals
• avoiding fatty or spicy foods
• taking over-the-counter treatments like antacids or laxatives

When to seek medical support

Speak to your prescriber if side effects don't improve or start to worry you. Get medical help straight away for signs of a serious reaction, like severe stomach pain, yellowing skin, severe vomiting or facial swelling.

For more information about side effects, please read the patient information leaflet.

Alternatives to Mounjaro

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