How much water should you drink on semaglutide — and what does this cost you?

The biggest misconception: hydration on semaglutide is free, so you can cut corners on the service

Here is the myth worth correcting first. People sometimes approach semaglutide treatment the way they approach a supermarket own-brand: find the cheapest version and manage the rest yourself. Water is free, the thinking goes, so if you know to drink plenty of it, what are you really paying for?

The answer is clinical oversight. Dehydration on a GLP-1 medicine is not just an inconvenience. Severe vomiting or diarrhoea (which can happen after a dose increase) can lead to kidney problems if fluid losses are not replaced promptly. Knowing how much water you should drink on semaglutide is a starting point, not a safety net. A prescriber who reviews your progress can spot early warning signs, adjust your titration schedule or pause treatment if your body needs time to settle. That is the thing a low headline price rarely includes. The NHS patient information for semaglutide lists dehydration as one of the signs that requires urgent medical attention, it is not a minor footnote.

So when you are comparing costs, the real question is not which provider has the lowest number, but what happens when something goes wrong at 9pm on a Sunday. That is where the price gap between providers becomes meaningful, and where aftercare, included or excluded, changes everything.

What UK private semaglutide pricing actually looks like right now

Private semaglutide (Wegovy) treatment in the UK is priced per pen or per month, and costs vary between providers and by dose. Since Eli Lilly raised Mounjaro's list price significantly from September 2025, the broader weight-loss medicine market has shifted upward too. For context, understanding how much water to drink on Wegovy is just one of the practical questions that comes up alongside typical private prices for weekly injection treatments, which have been widely reported in the range of roughly £149 to £375 per month depending on the dose and provider, figures that should be treated as indicative, not fixed, because they move.

What headline prices often exclude is where the real story sits. A quoted monthly figure may not include the initial consultation fee, the prescription charge, the cost of follow-up clinical reviews before dose increases, or next-day delivery. Some providers charge separately for each of those. Add them up across a six-month titration and the gap between the cheapest-looking option and a genuinely all-in service can close considerably. Our Wegovy price guide walks through what those line items typically look like and how to compare them properly.

If a payday lands mid-week and you want to place an order, that is a reasonable moment to do it, our team processes consultations the same working day for orders placed before midday, Monday to Friday. The prescription, dispatch and delivery all flow from there without you needing to chase anything.

What nume's price includes, and why we are not the cheapest

At nume, one price covers your consultation, prescription, treatment, and free next-working-day tracked delivery. There are no hidden fees and no subscription that rolls over automatically. Every repeat order goes back to a prescriber for clinical re-review before anything is dispatched, and questions such as how much water you should drink on Wegovy, your weight, and any side effects you have reported all inform that decision. You can read more about how our clinical team approaches ongoing care on the clinical team page.

We are not the cheapest option available. That is a deliberate choice, not an oversight. The infrastructure behind a same-day clinical review, a GPhC-registered pharmacy (registration number 9012878, verifiable at the GPhC register), seven-day aftercare and evidence-checked dose increases costs money. We think that is money well spent on a prescription medicine with a real titration schedule and genuine physiological effects. If you want to explore your options, the affordable Wegovy page covers how to think about value rather than just price.

For more on what the treatment itself involves, the Wegovy overview is a good place to start. Or if you are still weighing up which treatment suits you, the weight-loss treatments page sets out the landscape clearly.

Why cheapest is the wrong measure for a prescription medicine

A small saving per pen is not the measure that keeps you safe. Semaglutide is a prescription-only medicine because its effects on the body are real and significant, slowing digestion, suppressing appetite, altering how your kidneys handle fluid. Reconstituting your own vials also raises practical questions, including how much water to add to 5mg semaglutide and, more broadly, how much water you add to semaglutide at each concentration, details that require clear clinical guidance rather than guesswork. Getting it right requires a prescriber who knows your medical history, not a checkout process.

The MHRA has repeatedly warned about counterfeit weight-loss pens sold online, some containing insulin rather than semaglutide. Sellers offering these medicines without clinical assessment are a red flag; if a price looks dramatically lower than the market, that is worth treating with scepticism rather than excitement. Suspected sellers can be reported through the MHRA's Yellow Card scheme. The FAQs page covers common questions about verifying a legitimate provider. And if you want to talk through your situation before committing, our contact page is there for that.

Hydration is one part of managing semaglutide well. Clinical supervision is the other. Both matter, and only one of them can be provided by a regulated prescriber who has actually reviewed your case.