Doctor Prescribed Weight Loss Injections: What to Expect

You've found the injections online, but now you need an actual prescription

Picture this: you've spent an evening reading about Mounjaro and Wegovy, you broadly meet the BMI criteria, and you're ready to start. Then you realise that every regulated UK pharmacy requires you to go through a prescriber first. That isn't an obstacle placed in your way, it's the law, and it's there for good reason.

Tirzepatide and semaglutide are both classified as Prescription-Only Medicines under UK law. A prescriber (a doctor, an independent pharmacist prescriber, or a nurse prescriber) must review your medical history, current medications, and relevant health information before a prescription can be issued. For a medicine that slows gastric emptying, reduces appetite, and can interact with oral contraceptives or affect how your body absorbs other drugs, that review genuinely matters.

What's changed in recent years is where that consultation happens. You no longer have to book a GP appointment and wait three weeks. Regulated online pharmacies with their own GPhC-registered prescribers can do this same assessment remotely, lawfully, thoroughly, and often the same day. The process for getting weight loss injections prescribed online follows the same clinical standards as a face-to-face consultation; the location just differs.

One check worth doing before you hand over any payment: search the pharmacy's name on the GPhC's public pharmacy register. It takes about forty-five seconds, and it tells you immediately whether the service is registered. If it isn't listed, walk away.

What these medicines are and why a prescriber decides which suits you

The two licensed options are meaningfully different, and choosing between them isn't something a website should do on your behalf, that's the prescriber's job. Still, understanding the basics helps you have a more useful conversation.

Mounjaro (tirzepatide), made by Eli Lilly, is the only dual GIP and GLP-1 receptor agonist licensed for weight management in the UK. It activates two separate gut-hormone pathways involved in appetite regulation and blood-sugar control. It comes in six strengths from 2.5mg to 15mg, starting low to let your system adjust rather than for immediate effect. In the SURMOUNT-1 clinical trial, participants on the highest dose saw average body-weight reductions of around 20–21% over 72 weeks, figures that, until recently, were associated only with surgical intervention.

Wegovy (semaglutide), made by Novo Nordisk, works on the GLP-1 pathway alone. It has a longer track record in the UK, and the MHRA approved a higher 7.2mg maintenance dose in early 2026, narrowing the gap with tirzepatide's results. Both are once-weekly subcutaneous injections; both carry a Black Triangle designation, meaning they're under additional MHRA monitoring.

Which is appropriate for you depends on your medical history, any current medications, and how you respond to each dose level. The prescriber makes that call, not the medicine's marketing, and not this page. A useful starting point for the broader picture is the overview of weight loss injections covering both medicines side by side.

Who qualifies, and what the assessment covers

The licenced eligibility criteria give the prescriber a framework to work from. For both Mounjaro and Wegovy, the broad private prescription criteria are: adults with a BMI of 30 or above, or 27 or above alongside at least one weight-related condition. That condition might be high blood pressure, high cholesterol, obstructive sleep apnoea, or type 2 diabetes, among others. For some ethnic backgrounds, UK clinical guidance applies thresholds 2.5 kg/m² lower.

Meeting those numbers on paper doesn't automatically mean treatment is appropriate. A prescriber also considers what other medicines you're taking, your history with thyroid or pancreatic conditions, whether you're pregnant or breastfeeding (these medicines aren't recommended in either case), and whether you're under 18 (they aren't licensed for this age group). The assessment is a genuine clinical conversation, not a box-checking exercise.

If you want to understand whether you're likely to meet the criteria before starting a consultation, you can read about whether your doctor can prescribe weight loss injections and how that decision gets made, including the conditions that affect eligibility. The NHS route to weight loss injections has stricter, phased criteria, worth reading if you want to know how the two routes compare.

Side effects are part of the assessment conversation too. The most common ones are gastrointestinal (nausea, constipation, indigestion, and occasional vomiting) typically most noticeable after the first injection or a dose increase, and settling for most people within a couple of weeks. If you want to understand what clinical oversight looks like before you begin, it helps to read about how a prescribed weight loss injection is assessed, issued, and monitored by a regulated prescriber. The NHS patient page on tirzepatide lists these in plain language and is worth bookmarking for reference alongside your Patient Information Leaflet.

Cost, what's included, and the one question worth asking any provider

Private prescribing means you pay directly. The cost of these injections has shifted, Eli Lilly raised Mounjaro's UK list price from September 2025, and private market prices since then have typically ranged from around £149 to £375 per month depending on dose and provider, as widely reported. Context for those numbers is on the weight loss injection cost page.

The number that matters isn't the headline figure, it's what that figure includes. Some providers show a medicine price and charge separately for the consultation, prescription, delivery, and clinical follow-up. Others bundle everything. Ask before you commit: is the consultation included? Is the prescription fee? What happens if you have a question mid-treatment?

At nume, a single transparent price covers the consultation, prescription, medicine, and free next-working-day DPD delivery. Our clinical team includes GPhC-registered Independent Prescribers (real clinicians, not automated systems) who review every consultation the same day it's submitted. There's no subscription, no automatic renewal; every repeat order is reviewed again. You can read more about how we work on the about us page.

For a prescription medicine, price is an incomplete measure. The right question is whether the service is clinically sound, the supply chain is the licensed one, and the prescriber is accountable. Those are harder to fake than a low number.

If you'd like a prescriber to review your suitability, the first step is straightforward, and free.

Start your free consultation with our clinical team.