How to Get Air Bubbles Out of Mounjaro (October 2026)

01 · The short version

What to do if you see an air bubble in your Mounjaro pen

Stop, do not improvise, and go back to the instructions that came with your pen. The Mounjaro KwikPen is a pre-filled, multi-dose device, and the patient information leaflet sets out how to prepare it and how to inject.¹³ That leaflet, not a forum thread or a video, is the reference for how the pen is meant to be handled.

A practical sequence looks like this:

• Read the pen instructions in your leaflet again before you start, even if you have injected before.
• Check the pen looks as it should, with the cap on until you are ready, and that it has not been frozen or kept out of the fridge for longer than allowed.
• Set the dose by turning the knob until the correct number shows in the window.
• If something looks wrong or you are unsure, do not inject. Contact the pharmacy that dispensed it or your prescriber.

If you buy from us, our support team is available Monday to Friday, 9am to 5pm, on 0333 207 0413 or at support@everydaymeds.co.uk. Needles, a sharps bin and injection guidance come with every order.

02 · Your real safeguard

The dose window matters more than the bubble

You are not meant to judge the dose by looking at the liquid, and you are not meant to measure it by eye against the cartridge.

If you are tempted to fiddle with the pen to get rid of one, remember that the design is what protects your dose accuracy. Interfering with it, or trying to get more out of a pen than the four doses it is made for, is not something we support. For more on what to do with the remainder in a pen, see what to do with the remainder in a pen.

03 · Getting a pen

Where genuine pens come from

Bubble worries are easier to settle when you know your pen is genuine and has been stored properly. We supply Mounjaro through official LillyDirect supply, direct from Eli Lilly's UK distribution, and all six doses are in stock. Delivery is free next-day tracked delivery in temperature-controlled packaging, with same-day dispatch when ordered by 3pm.

Your first 2.5mg pen costs £129.99 with code FIRST40 (standard price £169.99), and every later order is £25 off the standard price. Ordering takes three steps:

• Free online consultation. A short health questionnaire, with no charge and no obligation. Start your free consultation.
• Prescriber review. A GPhC-registered prescriber reviews your answers. Payment is taken when you place the order; if the prescriber decides the treatment is not suitable, the order is refunded automatically in full.
• Dispensing and delivery. Our registered pharmacy dispenses your pen and sends it to you.

You can see the full range on our Buy Mounjaro page.

04 · Why people see bubbles

Why you might notice a bubble in the pen

Many people spot a bubble or a few tiny ones in the cartridge window and wonder if the pen is faulty. This is one of the most common worries among new injectors, and it is understandable. You are about to put a medicine into your body, and anything unexpected looks like a problem.

If you want a more specific walk-through of this question, we have two related pages: one on air bubbles in a Mounjaro injection and one on an air bubble in the Mounjaro pen.

05 · Do not use a syringe

Why drawing Mounjaro into a syringe is not the answer

Many bubble-removal tips online are written for vials and syringes, where you tap the barrel and push the plunger. Mounjaro in the UK is supplied as a pre-filled KwikPen, which is a different device with different instructions.¹ Those syringe techniques do not transfer to it.

Moving tirzepatide from a pen into a syringe, or pre-filling syringes yourself, is not how the medicine is licensed to be used. Altering doses outside the licence means unknown dosing accuracy and no safety data.¹

If you saw advice on peptide or compounded products, remember that it describes different products, not your prescribed pen.

06 · If you already injected

What if you have already injected and then noticed a bubble?

Stay calm, and watch how you feel over the next hours. Mounjaro is given under the skin, not into a vein, and the licensed sites are the stomach area at least 5cm from the belly button, the front of the thigh, or the back of the upper arm if someone else gives the injection.¹

If you feel unwell in a way that worries you, get medical help straight away. Tell your prescriber or pharmacist what happened, including which pen and dose it was.

You can also report a suspected problem, or any unexpected symptom, through the MHRA Yellow Card scheme.¹⁹ Reports help regulators spot patterns in how medicines and devices behave.

Do not inject a second dose to make up for a worry about the first. The rule on timing is clear: never take two doses within 3 days of each other.¹

07 · Storage and pen condition

Check storage first: it affects how a pen looks and works

Before blaming the pen for a bubble, check how it has been kept. Mounjaro pens belong in a fridge at 2–8°C and must never be frozen.¹³ Never use a pen that has been frozen.

Once a pen is in use, it can be kept out of the fridge not above 30°C for up to 30 days, which is useful for short trips, after which it should be discarded.¹³ Keep the cap on to protect the pen from light.

For an unopened pen that has been out of the fridge, do not rely on a day limit you remember from somewhere else. Figures circulating online often come from other countries' labels. Check the patient information leaflet and ask the pharmacy before using it.¹³ Unopened pens keep until the expiry date printed on the box when stored in the fridge.

When travelling, carry pens in hand luggage rather than hold luggage, because the hold can fall below freezing. A cool bag with the prescription label or a copy of your prescription is ideal.¹³ A pen that has been through a freeze is a good reason to contact the pharmacy rather than inject.

08 · Injecting step by step

A calm injection routine that leaves less room for worry

A consistent routine reduces the chance that you will hesitate over small things like a bubble. Mounjaro is injected once a week on the same day each week, at any time of day, with or without food.¹ There is no best time of day. What matters is picking a day and time you will remember. Many people choose a weekend morning so early side effects fall on days off.

• Take the pen out of the fridge and check the label, strength and expiry date match what you were prescribed.
• Wash your hands and choose your site, rotating it with each dose.¹
• Look over the pen. If it appears damaged, has been frozen, or you are unsure, stop and ask.
• Follow the injection steps in the leaflet exactly, setting the dose by the number in the window.¹³
• Dispose of the needle in your sharps bin, then return the pen to storage with the cap on.

09 · Missed or changed doses

If a bubble made you skip or delay your dose

Delaying an injection because you were unsure is the safe choice, but there is a window for catching up. If you miss a dose, take it as soon as you can within 4 days (96 hours) of the scheduled time, then carry on with your usual day.¹

If more than 4 days have passed, skip the missed dose entirely and take the next one on your normal day. Never take two doses within 3 days of each other.¹

You can also change your weekly injection day if needed, as long as at least 3 days (72 hours) have passed since your last dose.¹ If a pen problem keeps recurring, speak to the pharmacy about a replacement rather than working around it. Dispensed prescription medicines cannot be returned except faulty, damaged or wrong items, which you should report within 3 days.

10 · Leaks and other pen faults

Bubbles, leaks and other things that look wrong

A bubble is only one of several things that can make a pen look odd. Others include liquid at the needle, a cracked cartridge or a window that will not turn to your dose. Each is a reason to pause and check the leaflet, not to press on.¹³

If liquid appears after you finish, our page on what to do when a Mounjaro injection leaks out explains how to think about it, and why you should not repeat the dose.

Whatever the fault, keep the pen and its packaging, note the batch details on the box, and contact the pharmacy. That lets someone with the full facts help you, and it lets the issue be recorded properly.

11 · Why it is worth persisting

Keeping your treatment on track

In the SURMOUNT-1 trial of 2,539 adults, people taking tirzepatide alongside diet and exercise lost on average 15% of their body weight on 5mg, 19.5% on 10mg and 20.9% on 15mg over 72 weeks, compared with 3.1% with lifestyle changes alone.² These are trial averages, and individual results vary.

As a worked example, for someone starting at 100 kg, 20.9% is about 21 kg. Trial averages do not predict your own result, and treatment works alongside a reduced-calorie diet and increased physical activity, not instead of them.²

Progress is gradual by design. Think in months, not days, and judge it by trend rather than individual weigh-ins.¹ A single worrying pen is not a reason to abandon a plan; it is a reason to ask for help and get a clean replacement or answer.