The Mounjaro fifth dose

Mounjaro, also called tirzepatide, is a popular weight-loss injection that’s been making headlines for its incredible results—participants in the SURMOUNT-4 study using the Mounjaro 15mg dose lost 20.9% of their body weight in just 36 weeks! Each Mounjaro pen is designed to deliver four pre-measured doses, but some people notice a tiny bit of leftover liquid after the four doses and wonder if it’s a “fifth dose.” This leftover liquid, known as a “buffer,” ensures the pen delivers the correct amount each time—it’s not a full dose and isn’t safe to use because it’s not sterile and not meant for injection. So, stick to the four doses, follow your doctor’s advice, and enjoy the benefits of this game-changing treatment.

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What Is Mounjaro?

Mounjaro, also called tirzepatide, is a revolutionary weight-loss injection approved in November 2023 [1].

It’s specifically designed for adults who are obese (BMI over 30) or overweight (BMI between 27 and 30) and have weight-related health conditions, such as diabetes or high blood pressure [2].

How does Mounjaro work?

Mounjaro mimics two natural gut hormones, GLP-1 and GIP [3]. These hormones help with weight loss by:

1. Reducing hunger: You’ll feel less hungry, making eating smaller portions easier [4].
2. Making you feel full: You’ll feel satisfied after eating, so you’re less likely to snack or overeat [4].
3. Slowing digestion: Food stays in your stomach longer, keeping you full for a longer time [4].

How do you take Mounjaro?

Mounjaro is a once-a-week injection that comes in a convenient pen. Each pen contains four pre-measured doses, so it’s easy to use without any complicated measuring [5].

Each Mounjaro pen contains 3 ml of liquid, with each dose being 0.6 ml. Those of you quick at maths will have noticed that this means that some of Mounjaro is left over after injecting the fourth dose.

What is the “Mounjaro fifth dose”?

After using all four doses in the Mounjaro pen, you might notice a small amount of liquid left over. Some people call this the “fifth dose,” but it’s not a real dose. This leftover liquid, called a “buffer,” ensures each of the four doses is accurate.

Why you shouldn’t use the Mounjaro fifth dose?

It might be tempting to try and squeeze out that extra liquid, especially since Mounjaro can be expensive, but here’s why you shouldn’t:

1. It’s not measured correctly: The leftover buffer isn’t a proper dose. It might contain too much or too little tirzepatide, which means you could end up under-dosing or overdosing.
2. It could affect results: Using an inaccurate dose might make the medication less effective, slowing down your weight-loss progress.
3. It’s not safe: The buffer isn’t meant to be injected, and using it could lead to side effects or complications.

The Mounjaro fifth dose and the risk of overdose

Using more Mounjaro than prescribed can increase the chance of side effects like:

• Nausea: Feeling sick to your stomach.
• Vomiting: Throwing up.
• Diarrhoea or Constipation: Your digestive system might get out of whack, causing loose stools or difficulty going to the toilet.
• Indigestion: That uncomfortable feeling in your stomach after eating.

This is the active ingredient that helps with weight loss and managing certain health conditions.

What each Mounjaro pen contains?

The Mounjaro KwikPen is a pre-filled injection pen that contains a special ingredient called tirzepatide.

Each pen is super easy to use and comes with four doses of medicine already measured out, so there’s no guesswork involved.

Here’s a quick look at the different types of Mounjaro KwikPens and what they contain:

• Mounjaro 2.5 mg KwikPen: Each pen has four doses, with each dose containing 2.5 mg of tirzepatide in a 0.6ml solution.
• Mounjaro 5 mg KwikPen: Each pen has four doses, with each dose containing 5 mg of tirzepatide in a 0.6ml solution.
• Mounjaro 7.5 mg KwikPen: Each pen has four doses, with each dose containing 7.5 mg of tirzepatide in a 0.6ml solution.
• Mounjaro 10 mg KwikPen: Each pen has four doses, with each dose containing 10 mg of tirzepatide in a 0.6ml solution.
• Mounjaro 12.5 mg KwikPen: Each pen has four doses, with each dose containing 12.5 mg of tirzepatide in a 0.6ml solution.
• Mounjaro 15 mg KwikPen: Each pen has four doses, with each dose containing 15 mg of tirzepatide in a 0.6ml solution.

Each KwikPen is designed to deliver the exact amount of tirzepatide you need, depending on the dose your doctor has prescribed.

This makes it easy to use and ensures you’re getting the right amount of medicine every time. The pens are pre-filled and ready to go—just follow the instructions, and you’re all set!

If you have questions about Mounjaro or need help finding the right treatment, reach out to us at Courier Pharmacy—we’re always happy to help!

Mounjaro dosing

Why do you have to build up the doses of Mounjaro gradually?

When you start using Mounjaro, your doctor will gradually increase the dose over time. This is called “dose escalation,” and it’s done to help your body get used to the medication safely [5].

If you suddenly take more than your body can handle, it could overwhelm your system and worsen those side effects. That’s why it’s important to stick to the dose your doctor prescribed and avoid using any leftover liquid in the pen as an extra dose.

The right way to use Mounjaro: Dosing made simple

If you’re using Mounjaro, it’s super important to stick to the correct dosing instructions. Each Mounjaro pen is designed to give exactly four pre-measured doses, which are carefully calibrated to deliver the right amount of medicine every time.

So, the first rule? Use only the four doses per pen—no more, no less

Mounjaro gradual dose escalation: What it means and why it’s important

Mounjaro is designed with a gradual dose escalation plan, which means your doctor will slowly increase your dose over time. This step-by-step approach helps your body adjust to the medication, making you less likely to experience side effects like nausea or upset stomach.

In fact, during the SURMOUNT-1 trial, most side effects were reported at lower doses when people’s bodies were still getting used to the medication [6].

This is why it’s so important to follow your doctor’s instructions, not rush into higher doses or try to stretch the pen beyond its intended use.

Mounjaro dose escalation plan

Here’s a quick summary of how Mounjaro doses are typically increased:

What strengths of Mounjaro are available?

Mounjaro KwikPens come in these strengths:

• Mounjaro 2.5mg
• Mounjaro 5mg
• Mounjaro 7.5mg
• Mounjaro 10mg
• Mounjaro 12.5mg
• Mounjaro 15mg

Starting Mounjaro: Where do you begin?

When you first start Mounjaro, you’ll begin with the Mounjaro 2.5mg dose. This smaller dose is used for the first four weeks to help your body adjust to the medication.

After that, your doctor will gradually increase your dose based on how well you’re tolerating it and your weight-loss progress.

How does the Mounjaro dose progression work?

Mounjaro doses usually increase every four weeks, but the pace can vary depending on your needs:

• If you experience side effects, your doctor might keep you on a lower dose for a bit longer.
• If you’re happy with your results at a lower dose, you can stick with it.
• If you prefer to progress slowly, your doctor can adjust your schedule.

The maximum recommended dose is Mounjaro 15mg per week, and going beyond this can lead to serious side effects. Always follow your doctor’s advice to ensure safe and effective weight loss.

What are the Mounjaro maintenance doses?

These are the doses that you can stay on longer term, unlike the transition doses, which are designed to make the jump to higher doses more bearable.

The ideal maintenance dose of Mounjaro varies for each individual based on factors like how well you tolerate the medication and your overall health. The three Mounjaro maintenance doses are [7]:

• Mounjaro 5mg
• Mounjaro 10mg
• Mounjaro 15mg

A healthcare professional will help determine the best option for you. If you need guidance or have any questions, contact us for your FREE Mounjaro weight loss consultation.

Let’s settle this once and for all—there’s no such thing as a secret “fifth dose” in the Mounjaro KwikPen. Like most urban legends, it’s just a myth and this residual liquid is simply a buffer to make sure that you receive four accurate doses.

If you experience side effects or need more time to adjust, it’s okay to stay on a lower dose for longer. Combining Mounjaro with regular exercise and a balanced diet will help you get the best results. Not sure when to transition to a maintenance dose? Contact us for a FREE Mounjaro weight loss consultation.

When should you switch to a maintenance dose?

As your treatment progresses, your dosage will gradually increase to help your body adapt. This phase is often when you’ll notice reduced appetite and weight loss.

If you experience side effects or need more time to adjust, staying on a lower dose for longer is okay. Once you’ve reached your weight-loss goals or a dose that works well for you, it’s time to move to a maintenance dose.

Combining Mounjaro with regular exercise and a balanced diet will help you get the best results.

If you are not sure when to transition to a maintenance dose? Contact us for a FREE Mounjaro weight loss consultation.

The truth about the Mounjaro “Fifth Dose”

The leftover buffer isn’t designed to be used as a dose. It’s not safe, and it won’t work the way it’s supposed to.

So, instead, stick to the Mounjaro dose escalation program. This gradual increase in doses is carefully planned to help you lose weight effectively while keeping side effects to a minimum.

If you’re curious about Mounjaro or want to learn more about how it works, visit Courier Pharmacy for trusted advice and support.

What do you get when you order Mounjaro from Courier Pharmacy?

Along with your Mounjaro pen you also receive:

• Pen needles
• Alcohol swabs
• Shaprs bin
• FREE ongoing support and advice via email or phone.

Frequently asked questions about Mounjaro

Let’s simplify some of the most common questions about Mounjaro, the weight-loss injection. Whether you’re considering starting it or just curious, here’s everything explained in a way that’s easy to understand.

Who shouldn’t use Mounjaro?

Mounjaro isn’t for everyone and in some people it is not suitable [8]. You should avoid it if you:

• Are allergic to tirzepatide (the active ingredient) or other ingredients in the injection.
• Are pregnant or breastfeeding.
• Are under 18 years old.
• Have a history of medullary thyroid cancer (MTC) or Multiple Endocrine Neoplasia type 2 (MEN 2).
• Have had severe stomach or digestive problems like:
  • Gastroparesis (when your stomach empties too slowly).
  • Pancreatitis (inflammation of the pancreas).
• Have serious kidney or liver problems.
• Have diabetic retinopathy (eye damage caused by diabetes).

Can you drink alcohol while using Mounjaro?

It’s best to limit alcohol while on Mounjaro. Drinking can make side effects like nausea and dizziness worse. Want to learn more? Read our blog, Can You Drink Alcohol While Taking Mounjaro?.

Can you take Mounjaro with levothyroxine?

There aren’t any confirmed interactions between Mounjaro and levothyroxine (a thyroid medication), but it’s still important to monitor your thyroid levels [9].

Does Mounjaro cause thyroid cancer?

While early studies in animals raised concerns, there’s no strong evidence that Mounjaro causes thyroid cancer in humans. This was due to the presence of GLP-1 receptors in the thyroid of rodents, which are absent in humans [10].

How much weight can you lose with Mounjaro?

The SURMOUNT-1 trial showed these average weight loss results after 72 weeks [11]:

• 5mg dose: 16.4 kg (36.1 lbs).
• 10mg dose: 22.4 kg (49.4 lbs).
• 15mg dose: 23.8 kg (52.5 lbs) [1].

Does Mounjaro help with sleep apnoea?

Yes, studies suggest Mounjaro can help improve symptoms of sleep apnoea (a condition where breathing repeatedly stops during sleep) [12].

Does Mounjaro cause hair loss?

Around 5% of Mounjaro users have reported hair loss, but it’s unclear if this is due to the medication or rapid weight loss [13}.

How long do Mounjaro side effects last?

Common side effects like nausea, bloating, or constipation usually go away within a few days or weeks as your body gets used to the medication. Learn more in our blog, Mounjaro side effects.

References:

1. MHRA, 2023. MHRA authorises diabetes drug Mounjaro (tirzepatide) for weight management and weight loss. GOV.UK. Available at: https://www.gov.uk/government/news/mhra-authorises-diabetes-drug-mounjaro-tirzepatide-for-weight-management-and-weight-loss [Accessed 30 Nov. 2024].
2. Courier Pharmacy. (n.d.). Can you drink alcohol while taking Mounjaro? [online] Available at: https://courierpharmacy.co.uk/can-you-drink-alcohol-while-taking-mounjaro-2/ [Accessed 12 May 2025].
3. Coskun T, Sloop KW, Loghin C, Alsina-Fernandez J, Urva S, Bokvist KB, et al. LY3298176, a novel dual GIP and GLP-1 receptor agonist for the treatment of type 2 diabetes mellitus: from discovery to clinical proof of concept. Mol Metab. 2018;18:3–14. doi: 10.1016/j.molmet.2018.09.009.
4. Sinha R, Papamargaritis D, Sargeant JA, Davies MJ. Efficacy and Safety of Tirzepatide in Type 2 Diabetes and Obesity Management. J Obes Metab Syndr. 2023 Mar 30;32(1):25-45.
5. Eli Lilly and Company Limited. (2025) Mounjaro KwikPen 2.5?mg solution for injection in pre-filled pen: Patient Information Leaflet. Available at: https://www.medicines.org.uk/emc/product/15481/pil#gref (Accessed: 12 May 2025).
6. ClinicalTrials.gov. (2021). SURMOUNT-1: Tirzepatide for Weight Loss in Non-Diabetic Obese Individuals. Retrieved from https://clinicaltrials.gov/
7. Medical Mojo. (2025). Mounjaro maintenance doses. Available at: https://medicalmojo.co.uk/mounjaro-maintenance-doses/ (Accessed: 12 May 2025).
8. Medical Mojo. (2025). Who should not take Mounjaro? Available at: https://medicalmojo.co.uk/who-should-not-take-mounjaro/ (Accessed: 12 May 2025).
9. Medical Mojo. (2025). Mounjaro and levothyroxine: can you take them together? Available at: https://medicalmojo.co.uk/mounjaro-and-levothyroxine/ (Accessed: 12 May 2025).
10. Medical Mojo. (2025). Does Mounjaro cause thyroid cancer? Available at: https://medicalmojo.co.uk/does-mounjaro-cause-thyroid-cancer/ (Accessed: 12 May 2025).
11. Medical Mojo. (2025). Mounjaro weight loss week by week: how many kilos will you lose? Available at: https://medicalmojo.co.uk/mounjaro-weight-loss-week-by-week/#h-how-much-weight-can-you-lose (Accessed: 12 May 2025).
12. Medical Mojo. (2025). Mounjaro for sleep apnoea: read about the research. Available at: https://medicalmojo.co.uk/mounjaro-for-sleep-apnoea/ (Accessed: 15 May 2025).
13. Medical Mojo. (2025). Does Mounjaro cause hair loss? Available at: https://medicalmojo.co.uk/does-mounjaro-cause-hair-loss/ (Accessed: 15 May 2025).