Orlistat vs Wegovy: Which Is Better for Weight Loss?
Orlistat and Wegovy are both licensed for weight management in the UK, but they work in very different ways. Orlistat reduces how much dietary fat your gut absorbs. Wegovy contains semaglutide, a GLP-1 receptor agonist that acts on the brain's appetite and food-intake pathways. Wegovy has produced greater average weight loss in its major clinical trials than orlistat did in its own, although no trial has compared them directly. Orlistat costs considerably less privately, and Wegovy is now available as a daily tablet as well as a weekly injection. Which is suitable depends on a clinical assessment.
Orlistat vs Wegovy at a glance
| Orlistat | Wegovy (semaglutide) | |
|---|---|---|
| How it works | Reduces absorption of some dietary fat | GLP-1 receptor agonist; reduces appetite and food intake |
| How it's taken | Capsule with meals, up to 3 times a day | Daily tablet or weekly injection |
| Is it a GLP-1? | No | Yes |
| Trial weight loss* | 5.8 kg vs 3.0 kg placebo over 4 years | 14.9% (injection, 68 weeks); 13.6% (tablet, 64 weeks) |
| Main side effects | Oily stools, urgency, wind with discharge | Nausea, vomiting, diarrhoea, constipation |
| Medino price from** | £24.99 (84 capsules) | £99.99 (injection pen); £109.99 (30 tablets) |
| NHS access | Broader; can be prescribed by a GP | More restricted |
*Results from separate trials, not a head-to-head comparison. **Listed prices checked 7 October 2026; Wegovy prices rise with dose.
How orlistat and Wegovy work differently
Orlistat works in the gut. Wegovy works on appetite. That difference explains most of the other contrasts between them, from side effects to how each medicine is taken.
Orlistat inactivates gastric and pancreatic lipases, the enzymes that break down dietary fat into a form the body can absorb. The undigested fat passes out in stools; the NHS describes this as about a third of the fat from food. Very little orlistat reaches the bloodstream, and it doesn't act on hunger. Orlistat 120 mg (Xenical) is taken with each main meal containing fat, and a lower 60 mg strength (Alli, Orlos) is sold by pharmacies. For more on people's experiences with the treatment, see our Xenical and orlistat reviews.
Wegovy (semaglutide) mimics GLP-1, a hormone that helps regulate appetite and calorie intake. It acts on brain areas involved in hunger and the reward side of eating. It is licensed for adults with a BMI of 30 or more, or 27 to under 30 with at least one weight-related condition, as an injection or a tablet. Both forms start at a low dose that is increased gradually.
Is orlistat a GLP-1?
No. Orlistat is not a GLP-1 medicine. It's a gastrointestinal lipase inhibitor that reduces the absorption of some dietary fat. Wegovy (semaglutide) is a GLP-1 receptor agonist that acts on appetite and food intake. Orlistat has no effect on GLP-1 receptors and isn't designed to reduce hunger.
Which causes more weight loss: orlistat or Wegovy?
Wegovy has produced greater average weight loss in its major clinical trials than orlistat did in its major trials. Adults on Wegovy injections lost an average of 14.9% of their body weight over 68 weeks in STEP 1. In orlistat's largest long-term trial, XENDOS, participants lost an average of 5.8 kg over four years, compared with 3.0 kg on placebo.
There is no randomised trial comparing orlistat and Wegovy directly. These results come from separate studies involving different populations and study designs, so they can't tell us exactly how the two medicines would compare in the same group of patients.
| Evidence | Orlistat | Wegovy injection | Wegovy tablet |
|---|---|---|---|
| Study | XENDOS (Torgerson et al., 2004) | STEP 1 (Wilding et al., 2021) | OASIS 4 (Wharton et al., 2025) |
| Duration | 4 years | 68 weeks | 64 weeks |
| Population | 3,305 adults, BMI ≥30 | 1,961 adults, BMI ≥30 or ≥27 with a weight-related condition, no diabetes | 307 adults, BMI ≥30 or ≥27 with a weight-related condition, no diabetes |
| Dose | 120 mg three times a day | 2.4 mg once weekly | 25 mg once daily |
| Average weight change | −5.8 kg | −14.9% | −13.6% |
| Placebo | −3.0 kg | −2.4% | −2.2% |
| Lost ≥10% of body weight | 41% vs 21% placebo (at 1 year) | 66.1% vs 12.0% | 59.8% vs 14.1% |
Sources: XENDOS and Xenical SmPC; STEP 1 and Wegovy injection SmPC; OASIS 4 and Wegovy tablet SmPC.
Important: These are not head-to-head results and shouldn't be read as a prediction of individual weight loss. XENDOS reported weight change in kilograms; STEP 1 and OASIS 4 reported percentages.
What does an indirect comparison show?
A 2025 network meta-analysis in Nature Medicine estimated placebo-adjusted weight loss of about 3.1% with orlistat and 11.9% with semaglutide 2.4 mg. It found no head-to-head trial of the two medicines. Because this was an indirect comparison rather than a direct trial, it can't establish exactly how they would perform in the same patients, but it puts both medicines on the same scale.
How long before you know whether treatment is working?
Orlistat has a defined review point: the UK product information says it should be stopped after 12 weeks if a person hasn't lost at least 5% of their starting weight. Wegovy is increased gradually over several months, so its effect is judged later; for the injection, a decision on continuing is needed if 5% hasn't been lost after six months. Weight changes in the first few weeks aren't a reliable way to compare the two.
Orlistat vs Wegovy side effects
Orlistat and Wegovy both commonly cause digestive side effects, but of different kinds. Orlistat's mostly come from unabsorbed fat reaching the bowel. Wegovy's are mostly nausea, vomiting, diarrhoea and constipation, and are most frequent while the dose is being increased.
| Orlistat | Wegovy | |
|---|---|---|
| Most common effects | Oily spotting, wind with discharge, urgency, fatty or oily stools, abdominal pain | Nausea, vomiting, diarrhoea, constipation, abdominal pain |
| Linked to dietary fat? | Yes, more likely after higher-fat meals | No; mostly during dose increases |
| Other considerations | Can reduce absorption of fat-soluble vitamins and some medicines | Slows stomach emptying, which may affect some oral medicines |
Sources: Xenical SmPC; NHS; Wegovy SmPCs.
Orlistat. The most common side effects are bowel-related and become less frequent with longer-term treatment. Orlistat can interact with several medicines, including ciclosporin, warfarin, levothyroxine and some antiepileptics, so a pharmacist or prescriber needs to know what else you take.
Wegovy. Nausea was the most common side effect in both the injection and tablet trials, and most digestive effects were mild to moderate and short-lived. For more detail on the tablet, see our guide to Wegovy pill side effects.
Which has worse side effects: orlistat or Wegovy?
Neither has objectively worse side effects. The profiles are different, and tolerability varies between people. Orlistat's gastrointestinal effects are more likely after higher-fat meals, whereas Wegovy's gastrointestinal effects are not caused by dietary fat intake and tend to be most noticeable early in treatment. Previous experience with either type of medicine is worth discussing with a prescriber.
Orlistat vs Wegovy cost in the UK
Orlistat is considerably cheaper than Wegovy privately.
| Treatment | Medino price from* |
|---|---|
| Orlistat 120 mg (84 capsules) | £24.99 |
| Wegovy injection (1 pen, 4 weekly doses) | £99.99 |
| Wegovy tablets (30 tablets) | £109.99 |
*Listed prices checked 7 October 2026, including consultation and delivery. Wegovy's cost rises with the prescribed dose.
Wegovy prices also vary by formulation and provider. To compare current prices across UK pharmacies, see our Wegovy price comparison and Wegovy pill price comparison. A lower price doesn't make orlistat the right choice for everyone; cost is one factor among several.
Don't want injections? Orlistat vs the Wegovy tablet
If you'd rather not inject, orlistat is no longer the only licensed oral option. Since summer 2026, Wegovy has also been available in the UK as a once-daily tablet.
Orlistat and oral Wegovy are both taken by mouth, but they are pharmacologically very different treatments.
| Orlistat capsule | Wegovy tablet | Wegovy injection | |
|---|---|---|---|
| Medicine type | Lipase inhibitor | GLP-1 receptor agonist | GLP-1 receptor agonist |
| How often | With each main meal, up to 3 times a day | Once daily | Once weekly |
| How it's taken | With meals containing fat | On an empty stomach, then wait 30 minutes before eating, drinking or other medicines | Injection under the skin, with or without food |
Sources: Xenical SmPC; Wegovy SmPCs.
The Wegovy tablet and injection contain the same active ingredient but aren't simply interchangeable: they have different dosing schedules, and the tablet is absorbed less predictably. Which formulation, if either, is suitable is a decision for a prescriber. Our Wegovy pill vs injection guide covers the differences in more detail.
Can you take orlistat and Wegovy together?
Orlistat and Wegovy are not routinely used together, and you shouldn't combine them without a prescriber's advice. Neither UK licence covers using them in combination, there are no published trials of the combination, and NICE guidance presents them as separate options.
So if you're asking "can you take Wegovy and orlistat together?", there isn't the evidence to say it's effective or safe as a routine approach. Different mechanisms don't, on their own, make a combination safe. Practical concerns include:
- Overlapping side effects. Both commonly cause diarrhoea and abdominal symptoms, which could add up and increase the risk of dehydration.
- Absorption. Orlistat can reduce absorption of fat-soluble vitamins and some medicines, and semaglutide slows stomach emptying.
- Tablet instructions. Wegovy tablets have strict rules about food and other oral medicines.
If you're taking one and wondering whether adding the other might help, speak to your prescriber.
Can you switch from orlistat to Wegovy?
Yes, switching may be considered, but only after a clinical assessment. There is no orlistat-to-Wegovy dose conversion, because the medicines work in completely different ways. Orlistat and Wegovy are not dose-equivalent medicines.
Switching may be considered if orlistat hasn't produced sufficient weight loss or its side effects are difficult to tolerate. A prescriber needs to confirm that Wegovy is suitable, checking eligibility, medical history and other medicines. The licensed information doesn't set out an orlistat-to-Wegovy switching schedule; Wegovy is started at its licensed starting dose and increased gradually, as decided by the prescriber. Don't start Wegovy or stop a prescribed medicine without advice.
Orlistat vs Wegovy: which is better?
Wegovy has produced greater average weight loss in clinical trials, but that doesn't make it the better medicine for everyone. Orlistat works differently, costs much less privately and is easier to access on the NHS. Wegovy is now available as a daily tablet as well as a weekly injection. The right choice depends on eligibility, medical history, other medicines, tolerability and personal preference, assessed by a prescriber.
| If your priority is… | What to know |
|---|---|
| Greater average weight loss in trials | Wegovy has produced greater average weight loss, but there's no head-to-head trial against orlistat |
| Avoiding injections | Orlistat and Wegovy tablets are both oral, but very different medicines |
| Avoiding GLP-1 medicines | Orlistat is not a GLP-1 medicine |
| Lower private cost | Orlistat costs considerably less |
| Weekly dosing | The Wegovy injection is taken once a week |
| Different side-effect profile | Orlistat's are linked to dietary fat; Wegovy's are mainly nausea and bowel changes during dose increases |
This table is a decision aid for a conversation with a prescriber, not a prescribing guide.
Can you get orlistat or Wegovy on the NHS?
Orlistat is generally more widely available through the NHS than Wegovy. NICE recommends orlistat for eligible adults, and it can be prescribed in primary care, including by a GP. NHS access to Wegovy for weight management is more restricted: NICE recommends it only within specialist weight management services, for up to two years, for people meeting specific criteria. Wegovy tablets are not currently routinely available on the NHS. Being licensed doesn't mean a medicine is available to everyone on the NHS, and arrangements vary, so speak to your GP or local service.
References
- Neon Healthcare Ltd. Xenical 120 mg hard capsules – Summary of Product Characteristics. electronic medicines compendium (emc). https://www.medicines.org.uk/emc/product/2592/smpc
- Novo Nordisk Ltd. Wegovy FlexTouch solution for injection in pre-filled pen – Summary of Product Characteristics. emc, last updated 22 September 2026. https://www.medicines.org.uk/emc/product/13800/smpc
- Novo Nordisk Ltd. Wegovy 25 mg tablets – Summary of Product Characteristics. emc, last updated 16 June 2026. https://www.medicines.org.uk/emc/product/102347/smpc
- NHS. Orlistat: a medicine to treat obesity. Page last reviewed 6 May 2026. https://www.nhs.uk/medicines/orlistat/
- NICE. Overweight and obesity management (NG246): a guide for prescribing medicines to manage overweight and obesity. https://www.nice.org.uk/guidance/ng246/resources/a-guide-for-prescribing-medicines-to-manage-overweight-and-obesity-15299628589/chapter/Medicine-options-for-weight-management-in-adults
- Wilding JPH, et al. Once-weekly semaglutide in adults with overweight or obesity (STEP 1). N Engl J Med. 2021;384:989–1002. https://doi.org/10.1056/NEJMoa2032183
- Wharton S, et al. Oral semaglutide at a dose of 25 mg in adults with overweight or obesity (OASIS 4). N Engl J Med. 2025;393(11):1077–1087. https://pubmed.ncbi.nlm.nih.gov/40934115/
- Torgerson JS, et al. XENical in the prevention of diabetes in obese subjects (XENDOS) study. Diabetes Care. 2004;27(1):155–161. https://pubmed.ncbi.nlm.nih.gov/14693982/
- McGowan B, et al. A systematic review and meta-analysis of the efficacy and safety of pharmacological treatments for obesity in adults. Nat Med. 2025;31(10):3317–3329. https://pmc.ncbi.nlm.nih.gov/articles/PMC12532627/
- MHRA. First GLP-1 tablet for weight loss approved in the UK. 11 June 2026. https://www.gov.uk/government/news/first-glp-1-tablet-for-weight-loss-approved-in-the-uk
- NICE. Semaglutide for managing overweight and obesity (TA875). https://www.nice.org.uk/guidance/ta875/chapter/1-Recommendations
