The best weight loss injections for women in the UK right now

Step 1, work out which injection is the right starting point for you

Mounjaro and Wegovy both slow gastric emptying and reduce appetite, but they do so through different mechanisms. Mounjaro is a dual GIP and GLP-1 receptor agonist, the only medicine of its kind licensed for weight management in the UK. Wegovy targets GLP-1 receptors alone. In the SURMOUNT-5 head-to-head trial, published in the New England Journal of Medicine in 2025, tirzepatide produced greater average weight reduction than semaglutide 2.4mg over 72 weeks. That said, individual responses vary, and trial averages are population figures, not personal predictions.

For women specifically, a couple of things are worth knowing before you start. If you take an oral contraceptive pill, there is practical guidance specific to women on these injections that your prescriber will cover: tirzepatide can reduce pill absorption in the first four weeks of treatment and for four weeks after each dose increase, so an additional non-oral method (such as condoms) is recommended during those windows. NHS guidance notes there is no equivalent evidence of reduced pill effectiveness with semaglutide. Both medicines are not recommended during pregnancy, breastfeeding, or if you are actively trying to conceive.

The right injection for you is the one a prescriber selects after reviewing your full picture, BMI, comorbidities, other medicines, and your preferences. This page on finding the best injection for your situation goes deeper if you want to read more before booking. Men looking into these treatments can also find guidance written specifically for weight loss injections for men, covering how the clinical picture can differ.

Step 2, understand the licensed schedule before your first pen arrives

Both injections follow a gradual titration schedule designed to reduce gastrointestinal side effects. Mounjaro starts at 2.5mg, that first pen's job is to let your body adjust, not to produce the full therapeutic effect. The prescriber steps the dose up, typically every four weeks, through 5, 7.5, 10, 12.5 and up to 15mg. Wegovy follows a similar logic: 0.25mg rising through 0.5, 1.0, 1.7 and up to 2.4mg (with a 7.2mg single-dose pen now MHRA-approved for certain patients). The exact schedule and any changes to it are decided by your prescriber, not by the packaging.

Both medicines are injected subcutaneously once a week. Choosing the right site and rotating it properly helps avoid skin reactions. Injection site technique is worth reading before you start, most people settle on the abdomen or thigh. Storage is straightforward: both pens live in the fridge at 2–8°C; refer to the Patient Information Leaflet for the exact window during which a pen can be kept at room temperature, since that detail varies and the leaflet is the authoritative source.

Disposal matters too. Used pens and needles should go into an approved sharps container rather than general waste, your local council or pharmacy can advise on collection. The 1-litre sharps container available from our pharmacy is one option for home disposal.

Step 3, know the side effects and when to act

The side-effect profile for both medicines is led by gastrointestinal symptoms: nausea, loose stools, constipation, reflux and burping are the most commonly reported. These tend to be most noticeable after starting or stepping up a dose, and many people find they settle within a couple of weeks. Fatigue, headaches and injection-site reactions are also reported. The NHS tirzepatide patient page and the equivalent semaglutide page list these in full alongside the less common effects worth knowing.

One specific warning: in January 2026, the MHRA issued a Drug Safety Update highlighting acute pancreatitis as an infrequent but potentially serious side effect of GLP-1 medicines. If you develop severe stomach pain that radiates to your back, with or without vomiting, seek urgent medical help and stop the injection. Report any suspected side effect, including reactions you are unsure about, via the MHRA Yellow Card scheme, that data directly informs ongoing safety monitoring of these medicines.

A question our prescribers hear regularly: what happens if a dose increase lands the week before a holiday? The honest answer is that timing adjustments are a clinical decision, made with your prescriber. Aftercare is part of what a legitimate service provides. At nume, prescribers are available seven days a week precisely because these questions come up outside of normal Monday-to-Friday hours.

Step 4, access your prescription through a regulated route

Mounjaro and Wegovy are available on the NHS, but criteria are strict and phased. NHS England's current rollout for tirzepatide prioritises patients with high BMI and multiple weight-related conditions; Wegovy is available through specialist weight management services, where waiting lists are often long. Our treatment overview page covers both the NHS and private routes clearly.

Private treatment through a GPhC-registered online pharmacy is the practical route for many women who either do not meet NHS thresholds yet or cannot wait. The process at nume runs like this: a free consultation submitted online, reviewed the same day by a named GPhC-registered Independent Prescriber (a real clinician, not software), identity verified with photo ID and live weight confirmation on video, and (once clinically approved) the pen dispatched before the end of that working day if the order came in before noon. It arrives the next working day via DPD, in plain unbranded packaging, tracked to your door. Ordering before 12pm means it can arrive the following morning, which a lot of people find reassuring when they are juggling school and work around the clock.

The cost of weight loss injections in the UK varies by medicine, dose and provider; that page gives an honest breakdown of what a legitimate price includes. For a prescription medicine, the cheapest listing answers the wrong question. Clinical oversight, genuine supply chain and aftercare are what keep you safe. If you have read enough to decide you want to start, begin your free consultation and a prescriber will take it from there.