How to ask for weight loss injections — and what happens when you do

Before you ask: knowing whether you're likely to be in scope

Picture this: you've been reading about tirzepatide or semaglutide, you've looked at the trial results, and you're wondering whether this is something a prescriber would even consider for you. That wondering is the right first step. Before you speak to anyone, it helps to know roughly where you stand.

The licensed eligibility criteria for both Mounjaro and Wegovy cover adults with a BMI of 30 or above, or a BMI from 27 upwards alongside at least one weight-related condition. Conditions that count include high blood pressure, raised cholesterol, obstructive sleep apnoea, prediabetes and type 2 diabetes, among others. Thresholds are lower for some ethnic backgrounds under UK clinical guidance. BMI is a starting point, not the whole picture; a prescriber will consider your full medical history, any medicines you already take, and whether there are reasons the treatment wouldn't be appropriate, such as a personal or family history of certain thyroid conditions.

The NHS has its own, stricter phased criteria for who qualifies through the health service. Getting weight loss injections via the NHS currently involves meeting specific BMI and comorbidity thresholds that are narrower than the licensed SmPC criteria, and waiting lists vary considerably. Private treatment through a regulated pharmacy uses the licensed criteria and has no waiting list, subject to clinical approval.

Running the numbers (BMI, existing conditions, current medicines) before you have the conversation means you can make better use of the time. The NHS BMI calculator at NHS.UK takes less than two minutes.

Talking to your GP: what to say and how to frame it

Lots of people worry about being dismissed. GPs see this concern regularly, and most are familiar with both Mounjaro and Wegovy now that NHS prescribing for tirzepatide has begun rolling out in primary care. You don't need a rehearsed speech. A clear, factual opening tends to work well: "I've been reading about the licensed weight management injections. I meet the BMI criteria and I have [condition]. I'd like to discuss whether I might be a suitable candidate."

For a detailed look at how to structure that GP conversation (including what evidence to bring and what questions to expect back) our guide on asking your doctor specifically covers the preparation in full. One thing worth knowing: your GP is not the only clinical route. Whether you can ask your GP depends partly on your surgery's participation in the new GP contract and your local ICB's commissioning position.

If you're thinking of raising this at a GP appointment, timing a routine review around a Monday or a point in the month when you have a bit of breathing room (rather than squeezing it in as an afterthought at the end of a short appointment) gives the conversation the space it needs. Your GP cannot prescribe based on BMI alone; they'll want to discuss your health history, and that takes longer than five minutes.

Asking through a private online pharmacy: what the process actually looks like

A GPhC-registered online pharmacy follows the same clinical logic as a GP: a prescriber must assess your suitability before anything is issued. What differs is the structure and the timeline.

At nume, the process starts with a free consultation, a clinical questionnaire that covers your medical history, current medicines, weight history and goals. A real clinician reads it the same day; not software, not a routing algorithm. Identity is verified by photo-ID. Weight is confirmed on a live video call. If the prescriber determines treatment is clinically appropriate, the prescription is issued and the medicine dispatched the same day for orders placed before midday. Delivery is free and tracked, arriving the next working day in plain, unmarked packaging.

Every subsequent order is reviewed before it goes out, including dose increases, which require evidence that the previous dose has been tolerated. There are no subscriptions and no auto-renewals. If you want to understand the full weight loss injection landscape before deciding which medicine to ask about, that context is useful ahead of your consultation.

Before using any online pharmacy, check it on the GPhC register at pharmacyregulation.org. A legitimate pharmacy will have a valid registration number you can look up. Sellers offering these medicines without a prescription, or via social media with prices that seem unusually low, are a serious risk: the MHRA has warned repeatedly about counterfeit pens, some of which have contained insulin rather than the medicine on the label.

What to expect after the conversation: the clinical review and what follows

Asking is the start, not the end. Whatever route you take, expect questions rather than a rubber stamp. A prescriber who simply approves everyone without review is not a prescriber you want. The conversation will typically cover: your BMI and weight history, any conditions that might make treatment more or less suitable, what other medicines you're taking (some interact with the way GLP-1 medicines affect gastric emptying), your understanding of how the injections work, and what support you'll have alongside them.

If you're approved, you'll receive information on how to use your pen correctly. Once it arrives, reading through the Patient Information Leaflet before your first dose is not optional reading, it covers injection sites, storage, what to do if you miss a dose, and side effects to watch for. A practical walkthrough of the injection process is covered separately in our guide on how to inject weight loss injections.

Common side effects are mostly gastrointestinal (nausea, loose stools, indigestion, reduced appetite) and tend to be most noticeable in the first few weeks or after a dose step up. They ease for most people as the body adjusts. The NHS page on tirzepatide has a full side-effect profile worth reading before you start. You should seek medical help promptly for severe, persistent stomach pain that radiates to the back, which can signal pancreatitis.

The results question is almost always the next thing people want to know. How long weight loss injections take to work and what the clinical trial data actually shows is worth reading before you form expectations. For a fuller picture of the cost side, the treatment page sets out what's included in a private prescription through nume.