What Is Weight Loss Medication? UK Guide to Prescription Options

Who Might Benefit from Weight Loss Medication?

Improving diet and increasing physical activity are the foundations of weight management for everyone. However, for some people these measures alone are insufficient to achieve meaningful weight loss — particularly those with obesity, who face additional biological barriers including hormonal adaptations that actively resist weight loss and perpetuate hunger.

Prescription weight loss medication is designed to work alongside lifestyle changes, not replace them. It provides a physiological advantage that makes the calorie deficit achievable and sustainable for people who would otherwise struggle to maintain it. This is particularly relevant for those dealing with post-lockdown weight gain or other situations where body weight has become elevated and resistant to change.

Prescription Weight Loss Options in the UK

There are currently two main categories of MHRA-approved prescription weight loss medication available in the UK: GLP-1 receptor agonists (most notably liraglutide) and lipase inhibitors (orlistat). A newer generation of GLP-1 medications — including semaglutide — has been approved in the UK and is increasingly available via NHS and private prescribing pathways.

Liraglutide (Saxenda) — GLP-1 Receptor Agonist

Liraglutide is the active ingredient in Saxenda — a once-daily injection that works by mimicking GLP-1, a gut hormone that signals fullness to the brain. It reduces appetite, slows gastric emptying, and stabilises blood sugar, creating a natural calorie deficit without the severe hunger associated with conventional dieting.

• MHRA & FDA approved for chronic weight management
• Average 8–9% body weight loss over 56 weeks in clinical trials
• ~60% of users lose ≥5% body weight; ~33% lose ≥10%
• Once-daily subcutaneous injection via pre-filled pen
• Dose escalated gradually over 5 weeks to maintenance dose of 3mg
• Prescription required; available via NHS or private prescription

Common Side Effects of Liraglutide

The most common side effects are gastrointestinal — nausea, diarrhoea, and constipation — particularly during the dose escalation phase. These typically reduce significantly after the body adjusts to the medication. A small number of users experience more serious side effects, including pancreatitis, which requires immediate medical attention if severe abdominal pain develops.

Orlistat — Lipase Inhibitor

Orlistat is a lipase inhibitor that works by blocking the absorption of approximately one-third of the fat consumed in meals. It reduces the total calories absorbed from dietary fat, creating a calorie deficit without directly affecting appetite. The 120mg prescription dose is available as Xenical; a lower 60mg OTC dose is available as Alli without a prescription.

• MHRA approved; available in prescription (120mg) and OTC (60mg) forms
• Produces approximately 3–5% additional weight loss vs lifestyle alone
• Taken with each main meal containing fat (up to three times daily)
• Works through fat malabsorption — does not affect appetite
• Less effective than liraglutide, but useful for patients who cannot use injections

Comparing the Options

Eligibility for Prescription Weight Loss Medication

In the UK, prescription weight loss medication is clinically appropriate for adults who meet all of the following:

• BMI of 30 or above (obese), or BMI of 27 or above with a weight-related comorbidity (type 2 diabetes, hypertension, hyperlipidaemia)
• Have not achieved sufficient weight loss through lifestyle changes alone
• Are committed to ongoing dietary and activity modification
• Have no contraindications to the specific medication

Contraindications vary between medications. A full medical consultation — including a review of your medical history, current medications, and BMI — is required before any prescription is issued.

How to Access Weight Loss Medication in the UK

Prescription weight loss medication can be accessed via your NHS GP, an NHS specialist weight management service, or a GPhC-registered private online pharmacy such as Access Doctor. Access Doctor offers regulated online consultations reviewed by GPhC-registered pharmacist independent prescribers. If you meet the criteria, your prescription is dispensed and dispatched — typically arriving the next working day in discreet packaging.

Weight Loss Medication at Access Doctor

MHRA-approved prescription treatments including Saxenda (liraglutide). Online consultation reviewed by GPhC-registered pharmacist independent prescribers. Discreet next-day delivery.