How to Do Your Second Mounjaro Injection (October 2026)

01 · The core answer

How to inject your second Mounjaro dose

Your second Mounjaro injection follows the same routine as your first, using the pen you already started. Mounjaro is injected under the skin (subcutaneously) once a week, on the same day each week, at any time of day, with or without food.¹ Each KwikPen contains four weekly doses.¹ So there is nothing new to open and nothing to reorder yet. You simply pick the pen up from the fridge and repeat what you did last week.

The exact illustrated steps are printed in the patient information leaflet that comes with the pen, and that leaflet is the authority for the mechanics.¹³ If you want the same material from a different angle, our guide on how to inject the Mounjaro KwikPen goes through the pen itself.

• First, wash your hands and check you have the right day. Your second dose is due on the same weekday as your first.
• Next, take the pen from the fridge, check the label and look at the medicine through the pen window as the leaflet describes.
• Then attach a fresh needle from your supply, exactly as the leaflet shows, and remove the needle covers when it tells you to.
• Follow any preparation step the leaflet gives for your pen. Do not rely on a video or a friend's habit over the printed instructions.
• Turn the dose knob until the correct dose shows in the window.
• Choose a new site, clean the skin, inject as the leaflet describes, and dispose of the needle safely.

Needles, a sharps bin and injection guidance are included with every order from us, so you should not need to buy anything extra. If you are still waiting for your pen or are working out what to order next, our page on how to order your second dose explains the process.

02 · Setup

How to set up a Mounjaro pen for the second dose

Setting up the Mounjaro pen for your second dose means checking the pen, fitting a new needle and setting the dose in the window. Start by confirming the pen is the one with your name and strength on the label, and that it has been kept in the fridge with the cap on.

The dose is set by turning the dose knob until the dose indicator shows the correct dose in the window. The number you can see in the window is the check, not the sound you hear, so do not count clicks.

Still on the starting strength, the second injection is normally the same 2.5mg dose as your first. Everyone starts on 2.5mg, and after at least 4 weeks the dose increases to 5mg.¹ For a full picture of this stage, see our overview of the Mounjaro second dose.

03 · Where to inject

Where you can inject Mounjaro

Licensed injection 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

Rotate the site with each dose.¹ In practice that means your second injection should go somewhere different from your first. If you used the left side of your stomach last week, use the right side or a thigh this week. A simple habit is to note the site on your phone or in a tracking app after each dose, so you are not relying on memory seven days later.

Choose skin that is intact and free from irritation. Avoid areas that are tender, bruised or scarred. If you cannot reach the back of your upper arm yourself, do not try; that site is only licensed when someone else gives the injection. Our free companion app, GLPTrackr, can help you keep a record of dates and doses across your whole journey.

04 · Same day each week

Timing: the same day each week

The most important timing rule is to keep the same day each week. There is no "best" time of day: Mounjaro works the same morning or evening, with or without food. What matters is the same day each week.¹ Pick a day and time you will remember. Many people choose a weekend morning so early side effects fall on days off, and that is a sensible approach if your week is busy.

You can change your weekly injection day if needed, as long as at least 3 days (72 hours) have passed since your last dose.¹ If your second dose has landed on an awkward day, for example because you are travelling, this is the rule that decides what is possible. Do not move it closer than the rule allows just to fit a plan.

05 · Late or missed second dose

What if your second dose is late or missed?

If your second dose is late, the answer depends on how late. 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 That is the full answer to the common question about whether you can inject twice: you must not take extra injections to catch up, and you must not double up.

If you are struggling, contact us and our prescribing team can talk through the options. Our guide to taking your second dose covers the same ground in a shorter format.

06 · Storage and travel

Storing your pen between injections

Between injections, the pen goes back in the fridge with the cap on. Keep Mounjaro pens in a fridge at 2–8°C and never freeze them.¹ Once in use, a pen can be kept out of the fridge not above 30°C for up to 30 days — useful for short trips — after which it should be discarded.¹ Keep the pen cap on to protect it from light, and never use a pen that has been frozen.¹

You can fly with Mounjaro. Carry pens in hand luggage, because hold luggage can fall below freezing, ideally in a cool bag with the prescription label or a copy of your prescription.¹ In-use pens tolerate up to 30 days not above 30°C, so most holidays need no special arrangements; for hot climates use an insulated pouch. Unopened pens should be kept in the fridge and keep until the expiry date printed on the box. If an unopened pen has been out of the fridge, check with the pharmacy before using it rather than relying on a remembered day limit, because figures circulating online often come from other countries' labels.

07 · After the second injection

What to expect after your second injection

After the second injection, most people notice little that is new. The 2.5mg starting weeks are about adjustment, and experiences differ widely: some people notice appetite change and early loss in the first week, others feel little until a higher dose, and both are normal.¹ Mild nausea, altered appetite and tiredness in the first days after each injection are the commonest early effects and usually settle.¹

Early loss includes water weight, so the trend over weeks matters more than any single weigh-in. Weight loss on Mounjaro is gradual by design. The first weeks on 2.5mg are an adjustment phase and losses are usually modest; most measurable progress builds from 5mg onward, month by month.¹

For context on results, 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, and treatment works alongside a reduced-calorie diet and increased physical activity, not instead of them. Do not expect those figures from the second injection; they describe much longer treatment at higher doses.

If a symptom worries you or is not one you were told about, speak to your prescriber, and you can report suspected side effects through the Yellow Card scheme.¹⁹ We have more detail on what is normal in what to expect from your second dose and second dose side effects.

08 · Common mistakes

Common mistakes to avoid on the second jab

The commonest second-injection mistakes are small, and all are avoidable.

• The number in the window is the check, not the sound.
• Reusing the same site. Rotate the site with each dose.
• Injecting early. Moving your day is allowed only if at least 3 days have passed since your last dose.
• Doubling up after a gap. Never take two doses within 3 days of each other.
• Leaving the pen exposed. Keep the cap on, keep the pen out of heat and never use a frozen pen.

Another point: dose changes are your prescriber's decision. Many people settle at a maintenance dose of 5mg, 10mg or 15mg, and higher is not automatically better.¹ If you later need to plan costs for a higher strength, see our page on the Mounjaro 5mg price, and your next pen can be arranged through the Mounjaro pen page.

09 · Using the same pen again

Using the pen again: what repeats and what changes

When you use the pen a second time, the routine repeats but the details move on. The day, the dose strength and the pen are the same; the needle and the injection site are new. The medicine is still inside the pen from your first dose, which is why the same KwikPen is used for all four weekly doses.¹³

Do you need to prime the pen every time? Preparation steps are set out in the patient information leaflet for your pen. Read it again before the second dose rather than working from memory. Our page on using the KwikPen for the second dose sets out the same points with a pen-focused view.

Treatment is also reviewed over time. If you have lost less than 5% of your starting weight after 6 months on the highest dose you can tolerate, your prescriber will discuss whether continuing or stopping is right for you.¹ That is some way off from your second injection, but it shows why the early weeks are about routine, not results.

10 · Getting support

Getting help with your injections

If you are nervous about injecting, you can get support. Our prescribing team provides ongoing monthly reviews, dose-titration and follow-up assessments, plus side-effect support. Our support team is available Monday to Friday, 9am to 5pm, by email at support@everydaymeds.co.uk, by account portal chat or by phone on 0333 207 0413.

Mounjaro is a prescription-only medicine, supplied only after an online consultation reviewed by a GPhC-registered prescriber. It is used alongside a reduced-calorie diet and increased physical activity. Individual results vary, and this page is information, not a substitute for medical advice. You can read more about our approach on the weight loss clinic page.

11 · Serious side effects

Serious side effects: when to get help straight away

Serious side effects are uncommon but need urgent attention. Get medical help straight away for: severe, persistent stomach pain that may spread to your back, with or without vomiting (possible pancreatitis); pain in the upper right abdomen, fever or yellowing of skin/eyes (possible gallbladder problems); or signs of a severe allergic reaction such as swelling of the face or throat and difficulty breathing. If you take insulin or a sulfonylurea alongside Mounjaro, watch for low blood sugar (shakiness, sweating, confusion) — your prescriber may need to adjust those medicines.¹