In short: The cost of some private weight-management medicines has risen since September 2025, when the manufacturer of tirzepatide increased its UK list price for private supply. If cost is a concern, do not ration doses, split or tamper with pens, or buy from unregulated websites. Instead, speak to a prescriber about your options, which may include a planned change of treatment, a supported pause, non-medicine approaches, or checking whether you qualify for NHS treatment.

This guide, written by a Ready Health prescribing pharmacist for patients in Standish, Wigan, Chorley, Horwich and across the UK, explains what changed and how to keep your treatment safe.

Why have private weight-management medicine costs gone up?

In August 2025 Eli Lilly announced an increase to the UK list price of tirzepatide (brand name Mounjaro) for private supply, taking effect in September 2025. The company said NHS supply arrangements were not affected. Pharmacies and clinics set their own private prices, so the impact for patients has varied.

Demand for these medicines has also grown quickly, and regulators have repeatedly warned that this demand has attracted illegal sellers offering fake or unlicensed products.

What should you avoid if treatment becomes harder to afford?

Skipping or stretching doses without advice. Irregular dosing can bring back side effects when you restart and makes it harder for your prescriber to judge how treatment is working.
Splitting doses or "microdosing". Pens are designed to deliver specific licensed doses. Trying to draw out partial doses can lead to inaccurate dosing and a risk of infection.
Stockpiling. Ordering more than you need can put pressure on supply for other patients and increases the risk of medicines being stored incorrectly.
Buying from unregulated sellers. The MHRA has warned about fake weight-loss pens and illegal online sellers, including products that have led to hospital admissions. Only obtain prescription medicines from a registered UK pharmacy or clinic after a proper consultation.

How can you check a pharmacy or clinic is legitimate?

Check that the pharmacy is on the General Pharmaceutical Council (GPhC) register.
Check that a clinic providing prescribing services is registered with the Care Quality Commission (CQC) in England.
Be wary of anyone who supplies a prescription-only medicine without asking about your health, or who promotes these medicines through social media adverts or influencers.

What are the safe options if cost is a concern?

Talk to your prescriber first. They can review your progress, goals and dose, and help you plan any change rather than stopping suddenly.
Consider a planned switch. Changing to a different licensed medicine is sometimes appropriate, but it needs careful timing and usually a lower starting dose. See our guide to washout periods when switching medication.
Plan for stopping, if you decide to. Studies show that many people regain some weight after stopping these medicines, so a plan for nutrition, activity, sleep and follow-up support is important.
Check NHS eligibility. NICE recommends both tirzepatide and semaglutide for some people with obesity. In England, tirzepatide is being rolled out in stages through GP practices for prioritised groups, and semaglutide is available through specialist weight management services. Your GP can advise whether you qualify.

Frequently asked questions

Can I lower my dose to make treatment last longer?

Only if your prescriber agrees. Some people maintain progress on a lower licensed dose, but this should be a clinical decision, not a cost-saving workaround.

What happens if I stop my weight-loss medicine suddenly?

Appetite often returns over the following weeks and some weight regain is common. Stopping is not usually dangerous in itself, but plan it with your prescriber, especially if you take medicines for diabetes.

Is it safe to buy cheaper pens online?

Only from a registered UK pharmacy following a consultation. The MHRA has warned that fake pens are circulating and can cause serious harm.

Can I get these medicines on the NHS?

Possibly. NICE recommends them for specific groups, and access depends on your BMI, weight-related health conditions and local NHS services. Ask your GP.

Key takeaways

Private costs for some weight-management medicines rose from September 2025.
Never split doses, tamper with pens or buy from unregulated sellers.
Talk to a prescriber before changing, reducing or stopping treatment.
Check whether you are eligible for NHS treatment through your GP.
Diet, activity and ongoing support remain central whatever you decide.

For background on how the two main medicines compare, see our article on the head-to-head trial of tirzepatide and semaglutide.

Sources and further reading

Last reviewed: October 2026 by Shamir Patel, Independent Prescribing Pharmacist, Ready Health. This article is general information and does not replace advice from your own clinician. Brand names are trademarks of their respective owners.

If you would like to review your weight-management plan, you can book a weight-management consultation at Ready Health in Standish, Wigan. A prescriber will look at your health, goals and circumstances and discuss all suitable options with you.