At a glance
| Wegovy | Xenical | |
|---|---|---|
| Form | Weekly injection | 3x daily with meals |
| How often | Injection: once-weekly | Three capsules daily, taken with each fat-containing meal |
| Weight loss in trials | Up to 14.9% — STEP 1 (68 weeks) | Up to 8.5% — Sjostrom 1-year RCT (52 weeks) |
| FDA approved | 2021 | 1999 |
| Made by | Novo Nordisk | Roche (Xenical) / GSK (Alli OTC) |
| How it works | A GLP-1 analogue with an extended half-life of approximately one week. | Blocks pancreatic lipase enzymes in the small intestine, preventing approximately 30% of dietary fat from being broken down and absorbed. |
| Monthly cost, self-pay | ~$1,350/mo | $40–$400/moover-the-counter strength; prescription runs to $400 |
| Most reported reaction | Nausea 44% (STEP 1) | Oily/fatty stools (steatorrhoea) 27% (XENDOS) |
Every figure in this table is read from the same trial and label records used everywhere else on this site.
Weight loss in each drug's main trial
No head-to-head trial has compared these two drugs.
STEP 1 (68 weeks)
Sjostrom 1-year RCT (52 weeks)
In clinical trials, participants taking semaglutide lost on average up to 14.9% of their starting body weight, and participants taking orlistat lost on average up to 8.5%. Those numbers come from two different studies: STEP 1 enrolled 1,961 adults with obesity or overweight with comorbidities, no type 2 diabetes over 68 weeks against placebo, while Sjostrom 1-year RCT enrolled 743 adults with obesity over 1 year (52 weeks) against placebo. Who took part, how long each trial ran and what each drug was measured against all move the percentage, so the two figures are not a measured difference between the drugs.
Monthly cost, self-pay
The bar spans the range in each drug's price record — lowest listed price to highest.
Injection: ~$1,350/month list price. Novo Nordisk NovoCare programme available. The Wegovy pill is priced separately (see the oral pill entry).
over-the-counter strength; prescription runs to $400
Prescription Xenical ~$200–$400/month; over-the-counter Alli (60mg) ~$40–$60/month.
Self-pay prices are what the manufacturer or the pharmacy lists, not what most people end up paying. Wegovy: ~$1,350/month. Xenical: $40–$400/month. Insurance, dose and pharmacy all change both figures.
Side effects reported in the trials
STEP 1 and XENDOS did not report the same reactions, so there is no shared row to line up. Each drug's own reported rates are listed below.
- Nausea44%
- Diarrhoea30%
- Vomiting24%
- Constipation24%
From STEP 1
- Oily/fatty stools (steatorrhoea)27%
- Faecal urgency22%
- Oily spotting on underwear27%
- Faecal incontinence8%
- Abdominal pain/discomfort14%
From XENDOS
A rate is the share of trial participants who reported that reaction, not a prediction for any one person.
How they differ in practice
How you take it
- Wegovy — Two forms: once-weekly injection (2.4 mg) OR once-daily pill (25 mg). Same drug, similar results, very different cost and convenience.
- Xenical — Oral capsule 120 mg, three times daily with meals (prescription). Also available OTC as Alli at 60 mg.
How soon it acts
- Wegovy — Noticeable effects within 4–8 weeks; maximum weight loss typically reached by 60–68 weeks
- Xenical — Weight effects begin from the first week (related to calorie malabsorption), but significant loss takes 8–12 weeks
Heart and metabolic findings
- Wegovy — The SELECT trial (n=17,604) demonstrated a 20% reduction in major adverse cardiovascular events (MACE — heart attack, stroke, or cardiovascular death) vs. placebo in adults with established cardiovascular disease and obesity, without diabetes.
- Xenical — In the 4-year XENDOS trial, orlistat reduced progression from prediabetes to type 2 diabetes by 37% compared to placebo plus lifestyle changes.
As stated in each drug’s trial record — not a claim about which drug protects the heart more.
Other findings recorded
- Wegovy — 20% reduction in heart attacks and strokes (SELECT trial, established CVD); improved blood pressure and cholesterol across STEP trials
- Xenical — 37% reduction in progression to type 2 diabetes (XENDOS, 4 years); only approved obesity drug with a 4-year safety dataset
If you stop taking it
- Wegovy — In STEP 4, stopping semaglutide after a 20-week run-in led to significant weight regain.
- Xenical — Weight is typically regained after stopping.
Common questions
Written and maintained by one person · Built with agentic AI tools · Every number checked against the cited trial · Not medical advice
Clinical evidence — Semaglutide and Orlistat
No head-to-head trial has compared these two drugs.
- STEP 1 — Semaglutide (injection): 1,961 adults with obesity or overweight with comorbidities, no type 2 diabetes, 68 weeks. New England Journal of Medicine, 2021. View source ↗
- Sjostrom 1-year RCT — Orlistat: 743 adults with obesity, 1 year (52 weeks). International Journal of Obesity, 2000. View source ↗
- XENDOS — Orlistat: 3,305 adults with obesity, including those with prediabetes, 4 years (208 weeks). Diabetes Care, 2004. View source ↗
- Wegovy (semaglutide) injection and tablets — FDA prescribing information — DailyMed View source ↗
- Xenical (orlistat) — FDA prescribing information — DailyMed View source ↗
Next step most people take
Built with agentic AI tools and not a substitute for medical advice
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