How to Mix Tirzepatide 10mg: What UK Patients Need to Know (October 2026)

01 · The core answer

Do you need to mix tirzepatide 10mg?

No. Mounjaro is tirzepatide supplied as a pre-filled multi-dose pen (KwikPen) in six strengths: 2.5mg, 5mg, 7.5mg, 10mg, 12.5mg and 15mg.¹ The 10mg pen is already in solution and each pen contains four weekly doses.¹³

02 · Next step

What to do instead

If you want treatment, a GPhC-registered prescriber reviews a free consultation and decides whether Mounjaro suits you. See the Mounjaro pen and consultation for current prices, with all six doses in stock. For wider support, visit our weight loss clinic.

There is no safe, licensed way to add water to a KwikPen or to count units from one. Adding anything to a pen, or drawing medicine out of it, is outside its design. Read our explainers on water and tirzepatide and diluting Mounjaro for why.

03 · Using the 10mg pen

How the 10mg pen is used

Turn the dose knob until the indicator shows the correct dose in the window. You confirm the dose by the number shown, never by counting clicks.¹³ The pen will not let you dial past the medicine left inside. If the window will not turn to a full dose, the pen does not contain enough for one and should not be used for a partial injection.¹³

Follow the pen's instructions for the injection itself. Details are in our 10mg injection guide.

04 · Where 10mg fits

Where 10mg sits on the dose ladder

Everyone starts on 2.5mg once a week. After at least 4 weeks the dose increases to 5mg, then can step up by 2.5mg at a minimum of 4-week intervals up to a maximum of 15mg weekly, depending on response and tolerance.¹ Many people settle at 5mg, 10mg or 15mg; higher is not automatically better.¹¹

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

05 · Why we avoid vial mixing

Why vial-mixing is not advised

Powder sold as a 10 mg tirzepatide peptide is not the licensed UK product. Mixing it yourself means unknown dosing accuracy and no safety data. "Microdosing" (taking smaller or more spread-out doses than the pen is designed to deliver) is not licensed, not supported by the pen's design and not endorsed by any UK regulator.¹

Counterfeit and unregulated medicines are the subject of MHRA alerts, and you can report problems through the Yellow Card scheme.⁷ Genuine KwikPens from us come via official LillyDirect supply, dispensed by our GPhC-registered pharmacy (9012878).

06 · Storage

Storing your pen

Keep pens in a fridge at 2–8°C and never freeze them. Once in use, a pen can be kept out of the fridge at a temperature not above 30°C for up to 30 days after first use, and must then be thrown away. Do not use a pen that has been above 30°C or has been frozen. Keep the cap on to protect it from light.¹³