How to Inject a Mounjaro Single Dose Pen in the UK (October 2026)

01 · The core answer

Is the Mounjaro pen single dose or single use?

No. The Mounjaro supplied in the UK is a pre-filled multi-dose pen called the KwikPen, and it comes in six strengths: 2.5mg, 5mg, 7.5mg, 10mg, 12.5mg and 15mg.¹ Each KwikPen contains four weekly doses.¹ That means one pen is used across a month of weekly injections, not thrown away after a single use.

This matters because many online videos and written guides describe a differently designed pen. If a guide mentions steps that do not match the pen in your hand, stop and check it against the patient information leaflet in your box.

Our guides on the multidose pen question and on using the multi-dose pen cover the same device from other angles. If you were hoping to buy one weekly dose on its own, see whether you can buy a single dose of Mounjaro.

02 · What to do next

What should you do if you have a Mounjaro pen in front of you?

Read the leaflet that came with the pen, then follow the dialling and injection steps for the KwikPen.

If you have not started treatment yet, the Mounjaro pen starts at £169.99 for the 2.5mg starter pen, with in stock across all six doses. The consultation is free and reviewed by a GPhC-registered prescriber. Needles, a sharps bin and injection guidance are included with every order.

03 · Dialling the dose

How do you set the dose on a Mounjaro KwikPen?

You set the dose by turning the dose knob until the dose indicator shows the correct dose in the window.

Our page on where the dose window is on the Mounjaro pen shows you what to look for. The patient information leaflet in the box gives the illustrated, step-by-step handling of the pen, including attaching the needle, so keep it somewhere you can reach it.¹³

04 · Where to inject

Where can you inject Mounjaro?

Mounjaro is injected under the skin (subcutaneously). The 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 A simple habit is to move between sites in a set order, so you never have to remember where the last injection went. The back of the upper arm is only practical when another person can inject you, because you cannot reach it safely yourself.

Stomach injections are the most common choice for people injecting alone, as long as you stay clear of the belly button by the distance above. Choose skin that looks and feels normal, and avoid areas that are sore or damaged. If a site stays painful or you notice persistent skin changes, raise it with your prescriber.

05 · When to inject

What day and time should you inject Mounjaro?

Inject 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, because Mounjaro works the same morning or evening. What matters is the same day each week.

Pick a day and time you will remember. Many people choose a weekend morning so early side effects fall on days off, then stick to it. A phone reminder or the free GLPTrackr companion app can help you keep the routine.

Can you change your injection day?

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 Plan the move so the gap is never shorter than that, then carry on weekly from the new day.

06 · Missed doses

What if you miss a Mounjaro injection?

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

Do not double up to catch up. If you are unsure which side of the cut-off you are on, contact your prescriber or our support team before injecting. Support is available Monday–Friday 9am–5pm by phone on 0333 207 0413 or by email at support@everydaymeds.co.uk.

07 · Storing the pen

How do you store a Mounjaro pen?

Keep Mounjaro pens in a fridge at 2–8°C and never freeze them. Once in use, a pen 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.¹ Keep the pen cap on to protect it from light, and never use a pen that has been frozen.¹³

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.¹

08 · Travelling with your pen

Can you travel with a Mounjaro pen?

Yes, 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. Check destination rules for travelling with prescription injectables before you fly.¹

Because the pen holds several weekly doses, you can take the pen you are using rather than needing a separate device for each injection day away from home.

09 · Dose ladder

Which dose will your pen contain?

Everyone starts Mounjaro on 2.5mg once a week. This starting dose is about letting your body adjust, not about weight loss itself. After at least 4 weeks the dose increases to 5mg, and can then step up by 2.5mg at a minimum of 4-week intervals (7.5mg, 10mg, 12.5mg) up to a maximum of 15mg weekly, depending on how you respond and tolerate it.¹

Many people settle at a maintenance dose of 5mg, 10mg or 15mg. Higher is not automatically better, and your prescriber will guide the right pace.¹¹ Each strength is a separate pen, so when your dose changes you begin a new pen at the new strength. Our page on using the four-dose pen explains how the weekly doses are spread across a pen.

If you want to see how the strengths are supplied individually, read about the 15mg single pen or how a single dose of Mounjaro is priced.

10 · Altering doses

Is splitting or stretching doses safe?

No.

The licensed dose ladder already starts low at 2.5mg for tolerability. Altering doses outside the licence means unknown dosing accuracy and no safety data.

If you are tempted to adjust because a single-dose guide seems to describe something different, speak to your prescriber instead. Related pages such as the Mounjaro multiple dose pen explain the pen design, and our guide to a single pen and methotrexate covers a common medicine question.

11 · What to expect

What should you expect after the injection?

The first weeks on 2.5mg are about adjustment, and experiences differ widely. Some people notice appetite change and early loss in week one, others feel little until a higher dose, and both are normal. Early loss includes water weight, so the trend over weeks matters more than any single weigh-in. Mild nausea, altered appetite and tiredness in the first days after each injection are the commonest early effects and usually settle. Serious side effects are uncommon but need urgent attention. Seek immediate medical help 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.

Weight loss on Mounjaro is gradual by design. 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. These are trial averages, individual results vary, and treatment works alongside a reduced-calorie diet and increased physical activity, not instead of them.²

Tirzepatide has a half-life of about five days, so after a final dose it takes roughly four to five weeks to clear the system. There is no way to speed this up, and nothing needs doing while it clears.¹¹ Report any suspected side effect through the MHRA Yellow Card scheme.¹⁹

12 · Getting treatment

How do you get a Mounjaro pen in the UK?

Mounjaro is available on the NHS, but access is being phased in over several years. NICE recommends it for adults with a BMI of at least 35 plus at least one weight-related condition, and the NHS primary-care rollout began in June 2025 with the highest-need groups first (initially BMI 40+ with four or more qualifying conditions).⁴ Full rollout is expected to take years, which is why many people who meet the licensed criteria choose regulated private treatment rather than waiting.⁶ Mounjaro must not be used during pregnancy, and it should be stopped at least one month before trying to conceive. If you become pregnant during treatment, stop the medicine and tell your prescriber promptly.

Privately, the process with us has four parts:

• A free online consultation, a short health questionnaire with no charge and no obligation.
• A review by a GPhC-registered prescriber. 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 by our registered pharmacy (GPhC 9012878), with same-day dispatch when ordered by 3pm.
• Free next-day tracked delivery in discreet, temperature-controlled packaging.

Supply is official LillyDirect, meaning genuine KwikPens direct from Eli Lilly's UK distribution. New customers save £40 on their first order with code FIRST40, and an automatic £25 reorder discount applies to every future order (code DOSE25). Start with our weight loss clinic or view the single pen price guide and 15mg pen price page.

Mounjaro (tirzepatide) is a prescription-only medicine, used alongside a reduced-calorie diet and increased physical activity. Individual results vary. This page is information, not a substitute for medical advice.