The real cons of Wegovy — and what they mean for you

You're queasy, it's day three, and you're wondering whether this is worth it

That scenario plays out for a lot of people in the first weeks on Wegovy. Nausea is the most frequently reported side effect, and it can be accompanied by vomiting, loose stools, constipation, indigestion, or a combination of all of these. The NHS semaglutide page lists these as common reactions, and they tend to be most noticeable after starting treatment or after each dose increase. For most people they settle within a week or two. For some, they don't, or they return each time the dose goes up.

Beyond the stomach, fatigue and headaches show up in the first few weeks too. Injection-site reactions are possible but usually mild. Gallbladder problems are a less common but more serious concern: gallstones become more likely when body weight changes quickly, which is a relevant consideration for anyone losing weight at pace. Pancreatitis is rare but serious; in January 2026, the MHRA issued a Drug Safety Update specifically flagging acute pancreatitis as a known risk with GLP-1 medicines, emphasising the importance of seeking urgent help for severe or persistent stomach pain that travels to the back. That guidance is worth reading if you're weighing up whether to start. You can report any suspected side effects using the Yellow Card scheme.

None of this is unique to Wegovy, and for many people the side-effect burden is manageable. But it's one of the genuine cons, and anyone who tells you otherwise hasn't been paying attention.

The 'maximum two years' problem most people don't know about

Here's a detail that catches people off guard. NICE's recommendation for semaglutide (Wegovy) on the NHS (TA875) stipulates use for a maximum of two years, within a specialist weight management service. That's not a side note; it's baked into the recommendation itself. If you're accessing Wegovy through the NHS, you're accessing it within that framework, and continuation beyond two years isn't the default. For context on how NHS access works in practice (who qualifies, what's involved) the NICE TA875 guidance sets out the full criteria.

The deeper problem is biological. Semaglutide reduces appetite and slows gastric emptying while you're taking it. Stop the medicine, and those effects stop too. Studies have consistently shown that weight returns, often substantially, after treatment ends. That's not a failure of willpower; it reflects how these medicines interact with the body's weight-regulating systems. It does mean that Wegovy, for most people, is a long-term commitment rather than a short course, and the NHS framework doesn't always make that straightforward. If you'd like a broader look at both sides of the picture, the pros and cons of Wegovy for weight loss page goes into more depth on this balance.

The cost and access picture honestly laid out

On the NHS, access to Wegovy remains limited to specialist services with meaningful waiting times. In private practice, the monthly cost is not trivial. Following Eli Lilly's price adjustments in 2025, the wider GLP-1 market has seen private prices for weight-loss injectables range roughly £149–£375 per month depending on dose and provider, figures reported at the time. Wegovy sits within that range. Anyone researching the cheapest Wegovy available in the UK will find offers that look attractive; some are legitimate, some are not. Counterfeit and unlicensed weight-loss injections have flooded the market, and the MHRA's enforcement operations through 2025 uncovered approximately 20 million doses of illegally traded medicines worth around £45 million. Sellers offering prescription medicines without a clinical assessment are a red flag, full stop.

On cost more broadly: treatment price alone doesn't capture the full picture. A legitimate private service includes clinical assessment, prescription, dispensing, and aftercare. When any of those are missing, the saving isn't really a saving. You might also want to read about what makes up a semaglutide prescription so you know what you're comparing. Some people also look into whether a Wegovy alternative might suit them better, which is a reasonable question, and one a prescriber can actually answer for your specific situation.

Is Wegovy the right option, or is something else a closer fit?

Wegovy's cons don't exist in a vacuum. Tirzepatide (Mounjaro), a dual GIP and GLP-1 receptor agonist, showed greater average weight loss than semaglutide 2.4mg in the SURMOUNT-5 head-to-head trial published in the New England Journal of Medicine in 2025. The oral semaglutide tablet (Wegovy tablets) was approved by the MHRA in June 2026 for people who'd prefer not to inject; it has its own routine, taken first thing in the morning on an empty stomach, at least thirty minutes before anything else, including your first coffee of the day.

The point isn't that Wegovy is a bad option. For many people it's the right one. The point is that the cons of Wegovy look different depending on your health picture, your preferences, your eligibility, and how you weigh up a side-effect burden against expected benefit. That's a clinical conversation, not a Google search. A more detailed comparison of the trade-offs involved is available on the pros and cons of Wegovy page, or you can read about semaglutide's broader cons across its uses. When you're ready to talk it through properly, speak to our prescribers, the consultation is free, and a real clinician reviews your information the same day.