Mounjaro Injections (tirzepatide)

Mounjaro and Wegovy are both MHRA-approved medications for weight management, and although they both work in a similar way by reducing hunger and cravings, these weight loss injections are scientifically different.

Wegovy is a glucagon-like peptide-1 (GLP-1) receptor agonist containing Semaglutide, while Mounjaro is a dual GIP and GLP-1 receptor agonist containing Tirzepatide. 

Read more here about the differences.

While they are both once-weekly injections, they are not the same. Ozempic is used to treat diabetes, produced by Novo Nordisk, and contains the active ingredient Semaglutide. Mounjaro is used for weight management. It is made by the pharmaceutical company Eli Lily and contains the active ingredient Tirzepatide.

The Mounjaro KwikPen should be placed in your fridge (set between 2°C and 8°C) as soon as possible after delivery 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 travelling, it’s recommended to keep your Mounjaro KwikPen in your hand luggage and use a cool bag with an ice pack, if needed.

You might be slightly nervous the first time you’re getting ready to inject, 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

Make sure to thoroughly read and understand the user instructions that come with your KwikPen, following each step as directed. 

Our top injection tips include:

1. Reading the user instructions thoroughly
2. Washing your hands before starting
3. Choosing your injection site carefully to avoid side effects
4. Giving yourself plenty of time on injection day so you aren't rushed

Whether you inject in your abdomen, thigh or arm doesn’t affect the effectiveness of the drug.

It is your personal preference. Some people find that the abdomen is the least painful of the three injection sites, whereas the upper leg allows more visibility for injecting compared to the arm, which is a less visible option.

If you choose the same injection site, you should make sure it’s at least one fingertip space away from where you injected the week before.

Red bump

Yes, up to 1 in 10 people will experience redness, itching and swelling on the injection site. This is normal and these injection site reactions will disappear as your body gets used to the medicine. You can take an anti-histamine tablet and apply a cooling compress to the area to help treat this.

If for any reason these reactions become more severe, you should contact your healthcare provider right away as it may be a sign of a more severe allergic reaction.

Surplus liquid

Seeing liquid on the skin after injecting Mounjaro is normal and is commonly referred to as leakage or backflow.

It can be caused by many factors such as injection speed, volume of solution or the angle you insert the needle.

You must ensure that you leave the needle in the skin at least 3 seconds after injection, this should help prevent so much liquid on the skin. Never give yourself a second dose, no matter how much liquid is left on your skin.

Yes, you can. You can take Mounjaro up to 3 days early or more than 3 days after your last dose.

There is a small chance you might experience extra or stronger side effects when taking your next dose early, especially if you are also going up a strength. This isn’t a problem, but you should be aware.

This table shows the earliest you can take your next dose based on your current regular Mounjaro day.

Yes, you can take Mounjaro up to 4 days late. Then inject your next dose as usual on your original scheduled day. If it is over 4 days, you must skip the missed dose. Then inject your next dose as usual on your original scheduled day.

This all depends on how well you tolerate the dose you are on. If you are taking any strength of Mounjaro, you have no side effects and still losing weight, we advise that you stay on that dose.

On the other hand, if you have increased your dose of Mounjaro and you are experiencing unbearable side effects, you may want to consider reducing your dose.

If you have taken a dose of Mounjaro for at least 4 weeks, have no side effects and have stopped experiencing weight loss, you may have hit a weight loss plateau and could consider increasing your dose. You should reflect on your eating and exercising first.

When you request a change of dose our healthcare professionals will consider this and help you make the best and safest decision for you.

The "magical 5th dose" refers to the extra medication that remains in a Mounjaro pen after you've used the four standard doses. Each Mounjaro pen is designed and licensed to deliver four weekly injections of your prescribed dose, but some patients think there’s enough medication left over for a potential fifth injection. This isn’t the case.

The extra liquid is only there to accommodate for the liquid that may be lost during the priming stage before each weekly injection. There is not a secret 5^th dose in the pen.

You should always follow the official use instructions, as it can be unsafe to do otherwise.

Remember:

• The pen isn't designed to deliver a full fifth dose
• You wouldn’t be getting the correct amount of medication
• Mounjaro is licensed and optimised for four doses per pen only

Whilst there isn’t a specific diet to follow, it’s recommended that you follow a healthy & balanced diet. Focus on creating balanced meals that contain adequate protein and fibre. Make sure to drink plenty of fluids too.

You should drink at least 6 - 8 servings of water a day (one serving is a 250ml glass).

Try to avoid drinking with meals as this can cause you to feel too full and stop you from being able to eat your meal. We advise drinking water at least 30 minutes before or after a meal.

Aim for 3 meals a day, with snacks in between if needed, to provide your body with steady energy throughout the day. A balanced meal should look like:

• Filling half your plate with non-starchy vegetables, salad or fruit
• Filling a quarter with wholegrain carbohydrates
• Filling the other quarter with lean protein
• Include a small serving of healthy fats within your meal

One of the most important steps while using weight loss injections is maintaining a balanced, nutrient-rich diet. Even though you're eating less, choose foods that provide the essential vitamins & minerals your body needs. Prioritise lean proteins, colourful vegetables, whole grains and healthy fats to support your overall health during weight loss.

Rapid weight loss can sometimes lead to side effects like temporary hair loss if your body isn't getting enough nutrition. By focusing on nutrient-dense meals, you can help minimise these effects naturally.

If you're finding it challenging to meet your nutritional needs through food alone, oral vitamin supplements can provide additional support:

• Daily multivitamin – to cover any nutritional gaps from reduced food intake
• Biotin, zinc, and selenium (often found in skin, hair and nails formulas) – may help support hair health during weight loss
• Vitamin B complex and iron – can help combat tiredness from lower calorie intake

Remember, supplements should complement a healthy diet, not replace it. If you're concerned about your nutritional intake or experiencing side effects, let us know during your next consultation or contact our team here.

Any exercise is great and it's important to move your body daily. This might be something you need to build up to, and to get the best results from your weight loss journey you should consider a range of different exercise types. Try light aerobatic exercises like walking / brisk walking or jogging, and strength training such as lifting weights and doing squats to help build muscle and boost your metabolism.

The effectiveness of oral contraceptive pills can be reduced by up to 20% when using Mounjaro for weight loss. Oral contraceptives need to be absorbed by the body to work, but because Mounjaro slows down the emptying of the stomach (and may cause diarrhoea in some patients), this can reduce absorption and the reliability of the pill. 

It’s advised to use a barrier method of protection (such as condoms) when using Mounjaro, and especially in the first 4 weeks after you start treatment or increase dose levels. If you’re increasing dose levels every month, you may need to consider a longer term contraceptive barrier method.
 

If you become pregnant while taking Mounjaro, you should stop immediately and let your doctor know you’ve been taking it.  

According to studies, Mounjaro is most effective if it is taken continuously for 12 months or longer.

After 12 months, you can also decide whether you will stop treatment or stay on a maintenance dose.

You can stop Mounjaro at any point in your treatment, this is completely up to you. If you stop treatment we advise that you continue to maintain a healthier lifestyle to prevent any unwanted weight gain.

You can speak to a member of our trained team if you have any questions about stopping or continuing your treatment with Mounajro.

A Mounjaro maintenance dose is the dosage you continue taking once you've reached your weight loss goals or found the dose that works effectively for you.

Your maintenance dose is determined by several factors: how well you're tolerating the medication, the weight loss results you're achieving, and any side effects you experience. Some people maintain their results on lower doses like 5mg or 7.5mg, while others may need the maximum dose of 15mg to sustain their weight loss.

Remember, Mounjaro is most effective when combined with a healthy diet and regular exercise, regardless of your maintenance dose.
 

When you stop using Mounjaro, you will notice your appetite increasing or returning in full within a few weeks. If you haven't made any necessary lifestyle adjustments, you could regain some of the weight you lost. Regular exercise and healthy eating are two ways to stay on top of your weight loss and prevent regaining it.

Many patients also opt to take a maintenance dose, which is usually a lower dose level and helps them maintain their weight loss over the longer term.

There are not any reports of people experiencing withdrawal symptoms when discontinuing the use of Mounjaro. The medicine can take up to 25 days to entirely leave your system, so any side effects you are experiencing should also go by then.

Some patients are able to switch, but just because you’ve been prescribed Mounjaro, it doesn’t mean you can automatically switch to Wegovy. Explore our dedicated switching page to see if it might be suitable for you.

Yes, but this should be done under medical supervision with a proper “washout” period. This means letting the current treatment flush out of your system before switching to a different treatment. The length of the washout period depends on which medication you’re taking, the severity of any side effects and the dose level. Explore our dedicated switching page for more information.

Eli Lilly - who make Mounjaro - increased their prices across all strength levels from 1st September 2025. This means they are charging more per pen and this is affecting every Mounjaro KwikPen retailer