Mounjaro (Tirzepatide) 10mg Injection for weight loss

How to use Mounjaro Injections (tirzepatide)

Mounjaro is a prescription-only medication, so it’s important to use it as directed. Always follow medical advice from trained professionals and verified resources.

Mounjaro dose schedule

Mounjaro weight loss injections are available in several different doses: 2.5mg, 5mg, 7.5mg, 10mg, 12.5mg, and 15mg. The Mounjaro injection price increases as the pen strength increases, as you’re paying for more medicine per pen.

Everyone starting treatment begins with the lowest dose (2.5mg) for at least one month. After the first month of using Mounjaro, most people will move up to the next dose and continue to gradually increase it over several more months of treatment in a process known as dose titration.

The standard Mounjaro dosage guide for weight loss is as follows:

• Weeks 1 - 4: Mounjaro 2.5mg

• Weeks 5 - 8: Mounjaro 5mg

• Weeks 9 - 12: Mounjaro 7.5mg

• Weeks 13 - 16: Mounjaro 10mg

• Weeks 17 - 20: Mounjaro 12.5mg

• Weeks 21+: Mounjaro 15mg

The dose is increased slowly to reduce side effects like diarrhoea or sickness with Mounjaro. How quickly you move through the doses depends on how well you tolerate the medicine and your progress. If you’re still experiencing bad side effects at the usual time for a dose increase, your prescriber may recommend continuing at your current dose for longer.

You do have to increase the Mounjaro dose, as the starting strength is a non-therapeutic dose that helps your body adjust to the medicine, rather than support weight loss. However, it’s not necessary to reach the highest 15mg dose to successfully lose weight. Many people see good weight loss on lower maintenance doses, such as 10mg and 5mg doses.

Prices for the Mounjaro KwikPen do increase as the strength of the medication increases. For example, the 5mg costs more than 2.5mg, and the Mounjaro 7.5mg price is higher than both lower strengths because each pen contains more tirzepatide.

How to store Mounjaro

There are specific instructions on how to store Mounjaro you should follow. After delivery, Mounjaro pens should be stored in the fridge (2°C to 8°C) as soon as possible and must be kept refrigerated until you’ve opened it to administer your first injection. After that, it can be stored at room temperature (up to 30°C) for no more than 30 days and kept out of direct sunlight and away from direct heat.

If you’re wondering how to travel with Mounjaro, it's recommended to keep your Mounjaro KwikPen in your hand luggage and use a cool bag with an ice pack, if needed.

How to inject Mounjaro

Many people feel nervous about injecting Mounjaro for the first time, but the key is preparation and practice. There are several key stages to injecting:

1. Preparing your dose

2. Injecting your dose

3. Post-injection

These are broken down with simple, step-by-step instructions in the user instructions that come with your KwikPen. Make sure to thoroughly read and understand them before your first injection, following each step exactly as directed.

Our top injection tips include:

• Reading the user instructions thoroughly

• Washing your hands before starting

• Giving yourself plenty of time on your injection day so you aren’t rushed

Please note: From April 2026, updated versions of the Mounjaro KwikPen will begin appearing in the UK. The injection process remains the same, but the manufacturer has introduced a design update to help reduce confusion about leftover liquid in the pen. There will no longer be a so-called "5th dose" or "golden dose".

Have a problem with your Mounjaro pen?

You can get expert assistance from the Lilly Mounjaro CAREline experts on how to troubleshoot any issues with using your Mounjaro pen (see below for more details).

Important Note: If your pen must be collected by Lilly for testing, then they are unable to return it as it will have been out of the cold chain and will become unusable.

Mounjaro (Tirzepatide) UK Support Details

Lilly UK Careline & Medical Information

• Phone: 01256 315 000

• Note: Press 1 for the Medical Information department.

• Opening Hours: Monday to Friday, 10:00 am – 4:00 pm (Excluding Bank Holidays).

Reporting Pen Issues or Side Effects

• Technical Issues: If your KwikPen is jammed, leaking, or damaged, call the Careline at 01256 315 000.

• Side Effects: Report side effects to the manufacturer via the Careline or to the regulator via the MHRA Yellow Card Scheme.

Key Resources & Guides

• Medical Portal: Lilly Medical UK

• "How to Use" Guide: Step-by-step KwikPen instructions

• Official UK Site: lilly.com

Side effects of Mounjaro Injections (tirzepatide)

Most people taking Mounjaro for weight loss will experience some side effects, but they are mostly mild and generally improve over the course of treatment. In a clinical study, 79–82% of participants experienced at least one adverse event, and has been reflected in real-world use (11).

We’ve broken the possible side effects down below into the most common, less common, and rare but severe symptoms. The list is not exhaustive, and you should always read the Patient Information Leaflet that comes with your medication.

Common Mounjaro side effects

The most common side effects of Mounjaro are digestive symptoms, including (8):

• Diarrhoea

• Vomiting

• Constipation

These affect more than 1 in 10 people but are typically worse when starting treatment or increasing your dose and can often be managed at home (8). Some people will experience severe digestive symptoms that don’t improve with time. If you experience this, speak to your prescriber.

Mounjaro can give you heartburn, cause stomach pain, or leave you feeling fatigued, but these symptoms are slightly less common, affecting up to 1 in 10 people.

Vision changes

Most people using Mounjaro don't experience vision problems, though temporary blurred vision can occur in the first few weeks due to blood sugar changes as your body adjusts to treatment. For those with type 2 diabetes and existing Diabetic Retinopathy, rapid blood sugar improvements can occasionally trigger a flare-up.

If you experience sudden or painful changes to your vision, or changes that don’t ease after a few days, pause treatment and seek a same-day appointment with your optician, or call NHS 111 for out-of-hours care.

Serious side effects

If you experience any of the following serious side effects, stop usingMounjaro and contact your doctor immediately:

Uncommon side effects (may affect up to 1 in 100 people)

• Inflamed pancreas (acute pancreatitis) which could cause severe pain in the stomach and back which does not go away. You should see a doctor immediately if you experience such symptoms.

Rare side effects (may affect up to 1 in 1000 people)

• Severe allergic reactions (eg anaphylactic reaction, angioedema). You should call 999 if you experience symptoms such as breathing problems, rapid swelling of the lips, tongue and/or throat with difficulty swallowing and a fast heartbeat.

Remember, the full range of possible side effects are listed in the Mounjaro KwikPen Patient Information Leaflet. Not everyone will experience side effects, and some may be mild or short-term when you start treatment or move up a dose.

If you would like to talk to our Healthcare Advisors about any concerns around side-effects please call us on 01295 262925 or email help@oxfordop.co.uk.

Pancreatitis

Pancreatitis (inflammation of the pancreas) is a possible side effect with GLP-1 receptor agonists and dual GLP-1/ GIP receptor agonists. It may affect up to 1 in 100 people and could cause severe pain in the stomach and back which does not go away, with persistent vomiting and/or fever. Call your doctor if you notice any symptoms. In rare reports this can have serious or fatal outcomes.

Seek urgent medical attention if you experience severe, persistent abdominal pain, that may radiate to your back and may be accompanied by nausea and vomiting, as this may be a sign of pancreatitis.

Do not restart GLP-1 receptor agonist or GLP-1/GIP receptor agonist treatment if pancreatitis is confirmed and report suspected side effects through the Yellow Card scheme.

Remember, the full range of possible side effects is listed in the Mounjaro KwikPen Patient Information Leaflet. You can also refer to our Ultimate Guide to Mounjaro Side Effects page for more detailed information.

If you would like to talk to our Healthcare Advisors about any concerns around side effects, please call us on 01295 262925 or email help@oxfordop.co.uk.