Tirzepatide peptide mixing chart: what the search results won't tell you

Why a mixing chart exists, and why it should raise a red flag

Raw tirzepatide peptide powder is sold online, often marketed as a "research chemical". To use it as an injection, buyers must reconstitute it with bacteriostatic water, calculate a dose in micrograms per millilitre, and draw it into an insulin syringe. If you want to understand exactly how those calculations work, our tirzepatide mixing chart page explains what that process involves and why it carries real risk. The MHRA has not approved any compounded tirzepatide product for human use in the UK, and the supply chain for these powders is entirely unregulated.

This is not a technicality. In October 2025 the MHRA raided the first illicit UK site manufacturing counterfeit tirzepatide pens, seizing roughly 20 million doses of illegally traded weight-loss medicines with an estimated street value of around £45 million. Many fake products circulating online contain unknown substances, wrong concentrations, or no active ingredient at all. You can report suspect sellers directly through the MHRA's Yellow Card scheme, which accepts reports from patients as well as clinicians.

A question our prescribers hear most weeks is some version of: "I found it online for a fraction of the price, is it the same thing?" The honest answer is no. Purity, sterility, and concentration are guaranteed in a licensed pen. They are not guaranteed in a powder bought from a website with no regulatory oversight. More detail on what the licensed medicine actually is sits on our tirzepatide overview page.

What licensed Mounjaro actually looks like, and why no chart is needed

The NHS medicines page for tirzepatide describes Mounjaro as a pre-filled, multi-dose KwikPen containing a clear, colourless to slightly yellow solution. Each pen delivers four weekly subcutaneous injections at the pen's labelled strength. The dose is set at the factory. You attach a new needle, dial to the dose window, and inject. That is the entirety of the preparation step, a far cry from weighing lyophilised powder, calculating a reconstitution volume, and hoping your maths is right at 7am.

The six licensed UK strengths (2.5 mg, 5 mg, 7.5 mg, 10 mg, 12.5 mg, and 15 mg) are detailed in the NHS guide to tirzepatide, which is also a good reference for injection technique, storage, and what to do if a dose is missed. The prescriber decides which strength is appropriate based on a clinical assessment; patients do not choose a dose themselves, and they certainly do not calculate one from a chart. If you are comparing treatments or costs, our Mounjaro pricing page covers what a private prescription actually includes.

Storage for the pre-filled pen is refrigerated at 2–8°C; for exact room-temperature windows, the pen's Patient Information Leaflet is the definitive source. Injection sites are the abdomen, thigh, or upper arm, rotated each week. None of that requires a chart. It requires reading the leaflet once.

Eligibility for licensed tirzepatide, the criteria that matter

NICE recommended tirzepatide (TA1026, published December 2024) for adults with a BMI of 35 or above alongside at least one weight-related health condition. Lower thresholds apply for some ethnic backgrounds under UK guidance. Private prescribing through a GPhC-registered pharmacy follows the licensed indications: adults with a BMI of 30 or above, or 27 or above with a qualifying condition such as high blood pressure, type 2 diabetes, or obstructive sleep apnoea. The prescriber reviews the full clinical picture, not just the BMI figure.

That clinical review is what separates a legitimate prescription from a peptide powder ordered off the internet. At our pharmacy, a GPhC-registered Independent Prescriber reads every consultation (a real clinician, not automated software) on the same day the form is submitted. Our clinical team page gives more detail on how that oversight works. For a fuller picture of who is likely to be suitable, the weight-loss treatments overview sets out the eligibility framework plainly. If you want to understand where tirzepatide sits within the broader landscape of licensed weight-management options, the tirzepatide and peptide context page covers that ground.

One practical note on the NICE guidance: if less than 5% weight loss is achieved after six months at the highest tolerated dose, continuation is reviewed. That review should happen with a prescriber, not by adjusting a home-mixed dose upwards on the basis of an online chart.

If you have been using a mixing chart: what to do now

People arrive at compounded peptide products for understandable reasons, cost, access, frustration with waiting lists. Those frustrations are real. But the practical risks of unlicensed peptide powders include dosing errors that can cause severe nausea, hypoglycaemia, and acute pancreatitis. The MHRA issued a Drug Safety Update in January 2026 specifically highlighting pancreatitis as a known, serious risk with GLP-1 class medicines; that risk is compounded when the dose is uncertain.

If you have been reconstituting a tirzepatide peptide and want to move to the licensed medicine, a prescriber can assess your current situation. Transfer patients are reviewed with the same clinical rigour as new starters. Our FAQs page addresses common questions about switching, and the tirzepatide chart page offers further context on how dose progression works under medical supervision. The difference between a mixing chart and a prescriber-led titration schedule is the difference between guesswork and clinical oversight.