Mounjaro®
Starting from £179.99/mo
Start journey Learn moreWhat the evidence says, who qualifies, and how private access actually works
What are weight loss injections, and why do they require a prescription?
The two medicines prescribed privately for weight management in the UK are tirzepatide, sold as Mounjaro, and semaglutide, sold as Wegovy. Both are once-weekly subcutaneous injections administered using a pre-filled pen. They belong to a class sometimes called GLP-1 medicines, which mimic hormones your gut releases after eating. The effect is a meaningful reduction in appetite and, more slowly, in gastric emptying, so meals feel satisfying at smaller portions.
Mounjaro goes a step further, activating both the GIP and GLP-1 hormone receptors. It is the only dual-agonist weight-loss medicine currently licensed in the UK. Wegovy targets GLP-1 only. Both carry the MHRA's Black Triangle (▼) designation, meaning they are under additional monitoring as newer medicines.
They are Prescription-Only Medicines under UK law. That classification exists because the clinical picture matters: other medicines, certain health conditions and individual risk factors all affect whether a GLP-1 injection is appropriate for a given person. A prescriber needs to see that picture before making a decision. Our overview of weight loss injections covers the mechanism and licensed uses in more detail, including the steps involved in getting a prescription.
Do private weight loss injections actually work, what do the trial figures show?
A question our prescribers hear most weeks is whether the trial results are real-world realistic. The short answer is that the evidence base is unusually large for a weight-loss medicine.
SURMOUNT-1, which enrolled 2,539 adults with obesity and no diabetes over 72 weeks, found that participants on the highest tirzepatide dose lost around 20–21% of body weight on average, according to the trial published in the New England Journal of Medicine. The STEP 1 trial for semaglutide 2.4mg reported an average reduction of around 15% over 68 weeks. In a more recent head-to-head study (SURMOUNT-5, published in the NEJM in 2025) tirzepatide produced greater average weight loss than semaglutide 2.4mg in adults with obesity.
These are averages from clinical trial populations alongside reduced-calorie diets and increased activity. Individual results vary, and no specific outcome can be guaranteed. What the figures confirm is that, for many people, these medicines produce clinically meaningful changes when used under proper supervision. NICE's appraisal of tirzepatide (TA1026) formally recognised this, recommending it for NHS use in eligible adults.
Who qualifies for a private weight loss injection in the UK?
Private licensing eligibility follows the medicines' UK marketing authorisations. Adults with a BMI of 30 or above can be considered for either medicine. Adults with a BMI of 27 or above may also qualify if they have at least one weight-related health condition, for example, high blood pressure, raised cholesterol, obstructive sleep apnoea, or type 2 diabetes. For some ethnic backgrounds, UK guidance recommends applying these BMI thresholds 2.5 kg/m² lower.
BMI is a starting point, not the whole story. A prescriber also considers your medical history, current medicines, and whether any contraindications apply. People who are pregnant, breastfeeding, or trying to conceive are not candidates for these medicines. The same applies to those under 18.
Private access matters for people who don't meet NHS criteria (which currently requires a BMI of 40 with four or more qualifying conditions for tirzepatide in the first cohort) or who simply cannot wait. You can read more about how NHS access to weight loss injections works and the criteria involved if that route is relevant to you. If you'd like to explore your options, getting a private prescription for a weight loss injection starts with a consultation, not a waiting list.
What does getting a private weight loss injection actually involve?
The process through a regulated online pharmacy is straightforward but should never be trivial. You complete a clinical questionnaire; a GPhC-registered Independent Prescriber reviews your answers personally, not software, not a pre-set algorithm. That review includes checking your eligibility, any medicines that might interact, and confirming your identity and current weight. If the prescription is appropriate and you order before noon on a working day, your treatment is dispatched the same day and arrives the following working day via tracked DPD delivery, in plain unbranded packaging.
A legitimate private clinic or online pharmacy will carry a verifiable GPhC registration. You can check any pharmacy at the GPhC register before handing over personal or health information. Providers who offer these medicines without a clinical assessment are not operating within the law, and medicines sourced outside the licensed UK supply chain carry real safety risks, the MHRA has seized large quantities of fake pens and issued clear public warnings about counterfeit supply.
If you are looking for in-person options, information on private clinics offering weight loss injections and options near you can help you compare routes. Aftercare matters as much as the prescription itself, you should be able to reach clinical support if side effects arise or questions come up between doses. At nume, starting your free consultation takes a few minutes, and our prescribers are available to support you seven days a week throughout treatment.
Looking to start your weight loss journey?
Take a quick eligibility quiz to explore your options and see how we can support you.