Are weight loss tablets as good as injections? What the evidence actually shows

Do the tablets work as well as injections, by the numbers?

Honestly, not quite — but the gap is smaller than it used to be. Until June 2026, GLP-1 medicines for weight loss in the UK came only as injections. Then the MHRA approved the Wegovy tablet (oral semaglutide) as the first oral GLP-1 licensed for weight management in the UK, making this a genuinely new comparison.

In the OASIS 4 phase-3 trial (307 adults without diabetes, 64 weeks, alongside lifestyle changes) oral semaglutide produced an average weight loss of around 13.6% against roughly 2.4% for placebo. Among participants who adhered fully to treatment, that figure rose to about 17%. That is a meaningful result. By comparison, the SURMOUNT-1 trial reported average reductions of around 20–21% at the 15mg dose of tirzepatide (Mounjaro injection) over 72 weeks, and Wegovy injection at 2.4mg averaged approximately 15% over 68 weeks in the STEP 1 trial, as published in the New England Journal of Medicine.

So, on average trial data: injections edge ahead, particularly at the highest tirzepatide doses. But averages rarely tell the whole story. A 13–17% reduction in body weight is clinically significant by any standard, and if you want to understand how weight loss tablets compare to injections in more depth, including what the numbers mean in practice, we cover that in full detail. For someone who finds injections genuinely difficult to manage, the tablet that they actually take consistently may outperform the injection they hesitate over.

Why might someone choose tablets over injections, or vice versa?

The appeal of a tablet is easy to understand. No needles, no refrigeration, no sharps disposal, and the routine is straightforward, first thing in the morning, a small sip of plain water, 30 minutes before food or coffee. It fits neatly into a morning without any additional kit. Some people feel strongly about injections; for them, the tablet removes a real barrier.

Injections, on the other hand, are taken just once a week, which many people find easier to remember than a daily dose. Storage is the main consideration: both Mounjaro and Wegovy injection pens need to be kept refrigerated between 2–8°C (tucked in the fridge door is the typical spot) whereas the Wegovy tablet needs no refrigeration at all, which matters for travel.

There are also practical eligibility differences. The Wegovy tablet is licensed for adults with a BMI of 30 or above, or 27–29.9 with at least one weight-related condition. The injections carry broadly similar thresholds. A prescriber considers the full picture: other medicines you take, your medical history, how you've responded to previous treatments, and what you're actually likely to keep up with. You can read more about which format suits different situations and how clinical assessment shapes that decision.

Are the side effects different for tablets and injections?

Both formats share a GLP-1 mechanism, so the side-effect profile is broadly similar: nausea, diarrhoea, constipation, indigestion and fatigue are the most commonly reported, usually most pronounced when starting or after a dose increase, and often settling over days to a couple of weeks. The NHS medicines information for semaglutide covers both oral and injectable forms.

In the OASIS 4 trial, gastrointestinal side effects were reported by 74% of participants on the oral semaglutide compared with 42% on placebo, a higher rate than typically seen with injections, though most events were described as mild to moderate and transient. Whether that reflects the route, the dose-escalation speed, or variability between populations is still being studied. There are also absorption considerations specific to the tablet: it should be taken on an empty stomach with a small amount of plain water, and nothing else (including other oral medicines) for at least 30 minutes afterwards, which is different from the injection's more flexible timing.

For a thorough look at what weight loss injections involve before you compare formats, this page on what injections are actually like covers the practicalities and the evidence in detail. Questions about the risks specific to injections are addressed separately at our page on injection risks.

So which one should you go for?

Neither format is universally better. What the evidence shows is that injectable tirzepatide currently achieves the highest average weight reduction of any licensed UK medicine for weight management, while oral semaglutide offers a genuinely effective tablet option that was simply unavailable in the UK before summer 2026. Where you sit on that spectrum depends on your BMI, health conditions, other medications, and what you'll realistically stick with.

Cost is a factor too. The cost of weight loss injections varies by dose and provider, and the Wegovy tablet's pricing is still settling as supply builds. Our treatment overview page shows what's currently available through nume and what's included in the price. A prescriber who has reviewed your full clinical picture is the right person to make this call, not a comparison table, however useful one might be as a starting point.

If you'd like a clinician to help you work out which treatment fits your situation, you're welcome to check your eligibility with us. Every consultation is reviewed the same day by a real GPhC-registered prescriber, not automated software.