What age can you take weight loss injections in the UK?

The misconception: that these injections are suitable for teenagers who struggle with their weight

It's a question our prescribers hear most weeks, often from parents: could Mounjaro or Wegovy help a teenager who is significantly overweight? The honest answer is no, not through any legitimate UK route. Both medicines are licensed strictly for adults, meaning people aged 18 and over. This isn't a conservative policy choice by individual clinics, it reflects the terms of the MHRA product authorisation and the clinical trial programmes that underpinned it. Neither Mounjaro nor Wegovy has been evaluated for safety and effectiveness in under-18s in the UK, and prescribing them to anyone below that threshold would fall outside the licensed indication.

The concern is understandable. Obesity in younger people is a real and serious issue, and parents watching a child struggle deserve better than a flat refusal with no explanation. But the absence of a UK-licensed treatment for under-18s isn't a gap that a private pharmacy can fill, it's a regulatory boundary that exists because the evidence base simply isn't there yet. If a young person's weight is affecting their health, a GP is the right starting point; specialist paediatric pathways exist, even if access to medication within them is limited.

For adults, the situation is different. Once you reach 18, the conversation shifts to BMI, health conditions and clinical suitability, which is where the real eligibility assessment begins. The weight thresholds for weight loss injections set out the BMI criteria in plain terms.

What the UK licences say about adults, and whether there's an upper age limit

Neither Mounjaro nor Wegovy carries an upper age limit in their UK product licences. The SmPCs (Summary of Product Characteristics, published on the eMC) describe the licensed population as adults with a BMI of 30 or above, or a BMI of 27 or above alongside at least one weight-related condition such as high blood pressure, type 2 diabetes, high cholesterol or obstructive sleep apnoea. That applies whether you are 25 or 75.

In practice, older adults are more likely to have the kinds of complex health histories (polypharmacy, kidney function changes, cardiovascular conditions) that a prescriber will want to assess carefully. That doesn't disqualify anyone automatically; it means the clinical review carries more weight. A 68-year-old with well-managed hypertension and a BMI of 34 may well be a suitable candidate. A 70-year-old on multiple interacting medicines may need more careful thought. This is exactly why the NICE guidance on tirzepatide (TA1026) and semaglutide (TA875), published by the National Institute for Health and Care Excellence, frames these medicines as part of a managed clinical programme rather than a standalone product anyone can simply purchase.

The broader question of whether you can take weight loss injections covers the full range of clinical considerations beyond age alone.

Private treatment at 18 versus NHS access, the threshold isn't just age

Reaching 18 opens the door to clinical assessment; it doesn't automatically open the door to treatment. Through the NHS, access to Mounjaro is currently restricted to adults meeting quite specific criteria, including high BMI thresholds and the presence of multiple weight-related conditions, as part of a phased rollout. Wegovy is available through specialist weight management services, often with significant waiting times. The NHS medicines page for tirzepatide sets out how the medicine works and what patients should expect.

Private treatment through a regulated online pharmacy offers a different route for adults who meet the licensed criteria but don't yet qualify under the NHS thresholds, or who simply can't wait. At nume, every consultation is reviewed by a GPhC-registered Independent Prescriber (a real clinician, not automated software) who checks age, BMI, health history, current medications and any contraindications before any prescription is issued. There are no shortcuts in that process. If you're wondering whether you can take weight loss injections for just a month, that's something a prescriber can talk through with you once treatment has been established. You can read more about how long treatment typically continues once it has been established.

For context on what private treatment involves financially, the cost of weight loss injections in the UK covers the landscape honestly, including what a legitimate price should and shouldn't include.

Pregnancy, breastfeeding and other age-adjacent considerations

Age isn't the only life-stage factor a prescriber considers. These medicines are not recommended during pregnancy, while breastfeeding, or for women who are actively trying to conceive. If any of those situations apply, treatment would not be appropriate regardless of age or BMI. Women of childbearing age taking weight loss injections are advised to use effective contraception; for tirzepatide specifically, oral contraceptives may be less reliably absorbed in the early weeks of treatment, so an additional non-oral method is recommended for the first four weeks and after each dose increase. This is documented in NHS guidance on weight management injections and is something a prescriber will discuss during the clinical review.

These aren't small print, they are central to a safe assessment. The same applies to any history of medullary thyroid carcinoma or certain gastrointestinal conditions, which would prompt a more detailed prescriber conversation regardless of how straightforwardly a person otherwise meets the age and BMI criteria. If you have questions before starting a consultation, the frequently asked questions cover many of the practical points, and our team is reachable through the contact page if you need something more specific.

Ready to find out whether treatment is right for you? Start your free consultation and a GPhC-registered prescriber will review your details the same day.