How much bac water should you mix with 30 mg tirzepatide?

What licensed tirzepatide in the UK actually looks like, and why mixing doesn't enter the picture

The MHRA's guidance on GLP-1 medicines is clear: the only legally supplied tirzepatide for weight management in the UK is Mounjaro, produced by Eli Lilly as a pre-filled, multi-dose KwikPen in strengths from 2.5 mg up to 15 mg. Each pen contains four pre-measured weekly doses. You dial the dose, you inject, that is the entire process. There is no powder, no vial, no syringe to fill, and no bacteriostatic water at any point. If a product is being sold as 30 mg tirzepatide requiring reconstitution, it is not Mounjaro. It is not an MHRA-licensed medicine. And it is not legal to supply it in the UK as a treatment.

This distinction sits at the heart of the pricing question many people are actually asking when they search for mixing ratios. Unlicensed compounded tirzepatide sometimes appears online at prices well below the legitimate market, and questions such as how much bac water to use for 30 mg tirzepatide can look like a technical detail rather than a warning sign. It isn't. The MHRA has raided a domestic manufacturing site producing counterfeit tirzepatide pens and has seized roughly 20 million doses of illegally traded weight-loss medicines with an estimated street value of around £45 million. You can read more about the genuine safety risks on the Mounjaro overview page, and you can verify any online pharmacy's registration status directly on the GPhC register.

The practical upshot: if someone is telling you how much water to mix with 10 mg tirzepatide, they are not describing a licensed UK product. If you want to understand how much bac water to mix with tirzepatide and why that question simply does not apply to anything legally available here, that page sets it out clearly. Report suspect sellers at the MHRA's Yellow Card portal.

How UK private pricing for licensed tirzepatide actually works

Understanding the real cost structure helps cut through a lot of confusion. Licensed Mounjaro is priced per pen, per month, and the price varies by dose. Following Eli Lilly's UK list price revision in September 2025, private market prices for a single pen have been widely reported to range from roughly £149 to around £375 a month depending on the strength and provider. These are the only £ figures that reflect the legitimate, licensed market, everything else is a different product or a different risk profile.

Those headline figures, though, are where the comparisons get tricky. Some advertised prices cover the medicine alone. They don't include the prescribing consultation, the clinical assessment, the prescription fee, or the delivery charge. By the time each element is added separately, the apparent saving often shrinks or disappears entirely. The full breakdown of Mounjaro pricing in the UK walks through what to look for line by line.

We understand this can feel disheartening, especially if you've spent time looking for a more affordable route and found what looked like a much cheaper option. That's a completely reasonable place to land. The price gap between licensed and unlicensed products is real, and it exists precisely because licensed products carry clinical oversight, quality controls, a cold chain, and a prescriber who is accountable for your care.

What nume's pricing includes, and what we don't offer

nume is not the lowest-priced route to tirzepatide. That's a deliberate position. What a single price at nume covers is: your consultation, the prescriber's clinical review, the prescription, the medicine from Eli Lilly's authorised UK supply chain, and free next-working-day DPD delivery in plain packaging. There are no add-on fees at checkout. There are no subscriptions and no auto-renewals; each repeat order is clinically reviewed before it is approved. Current treatment pricing is listed on the weight-loss treatments page.

We also don't run discount codes, voucher schemes or promotional pricing. If you've seen a code advertised for tirzepatide from any seller, treat it as a flag: prescription-only medicines supplied with price incentives and no verifiable clinical assessment are a recognised pattern in the counterfeit market. A named GPhC-registered Independent Prescriber reads every consultation at nume, you can read more about our clinical team's approach on the clinical oversight page.

For a prescription medicine, price is the wrong question to lead with

The licensing framework for tirzepatide exists because the medicine has real effects on the body (slowing gastric emptying, reducing appetite, and producing significant metabolic change) and those effects need clinical supervision. NICE's appraisal of tirzepatide, TA1026, sets out the evidence base and the eligibility criteria that inform responsible prescribing. None of that infrastructure exists around unlicensed compounded products.

The right question isn't which price is lowest. It's whether the supply chain is legitimate, whether a qualified prescriber has assessed whether this treatment suits you, and whether there's clinical support if something doesn't go to plan. Those things aren't add-ons to the service, they are the service. You can explore what licensed treatment looks like and whether it might be appropriate for you on the weight-loss treatments overview, or go straight to a free consultation with our prescribers to have your questions answered by a clinician directly.

If you're still looking into the reconstitution side of things (for example researching how much bac water to mix with 10 mg tirzepatide) the short answer remains the same: for licensed UK treatment, it isn't.