Yes, and the effect size is published to one decimal place. In the largest trial reproduced in the FDA label — 1,961 adults with obesity or overweight and no type 2 diabetes, 68 weeks — mean body weight fell 14.9% on semaglutide 2.4 mg and 2.4% on placebo.
That is the approved injectable product. Whether a compounded semaglutide works is a different question with a different answer, and it is at the bottom of this page: no trial of any compounded semaglutide product has ever been published.
Weight, by trial and by dose
Every weight-reduction study in the label, at its primary endpoint. In all of them both arms received a reduced-calorie diet of roughly 500 kcal/day deficit and physical activity counselling, so the placebo column is what diet and counselling did on their own.
Wegovy label, Tables 8, 11 and 12. Mean percent change in body weight from baseline, least squares means, intention-to-treat.
Three patterns are worth pulling out. Type 2 diabetes blunts the result — 9.6% instead of 14.9% at the same dose. Intensive lifestyle therapy raises both arms, not just the drug arm. And tripling the dose from 2.4 mg to 7.2 mg bought 3.3 percentage points in Study 8, a difference the label reports as statistically significant and which you can weigh against the adverse-reaction gradient over the same dose step.
The mean hides the spread
A mean of 14.9% does not mean everyone lost about 15%. The responder analysis from the same trial is more informative:
Wegovy label, Table 8 — Study 2, n=1,961.
So roughly one in six treated patients did not reach 5%, and roughly one in three reached 20%. The label does not publish a way to tell in advance which group anyone is in, and states only that weight reduction was observed irrespective of age, sex, race, ethnicity, baseline BMI, baseline weight and level of renal impairment.
Note the placebo column too: 31.1% of people on a placebo injection lost at least 5% of body weight over 68 weeks. That is not a quirk of one trial. A meta-analysis of 69 placebo-arm datasets covering 20,454 patients in obesity drug trials found 20.4% of placebo-treated participants reached 5% loss and 8.3% reached 10%.
What happens when you stop
The label contains a withdrawal trial, which is the closest thing to a direct answer. 902 patients were escalated to 2.4 mg over a 20-week run-in; the 803 who reached the full dose were then randomised either to continue or to switch to placebo for the remaining 48 weeks.
From week 20 to week 68, the continuing group lost a further 7.9%. The group switched to placebo gained 6.9% — a 14.8 percentage point difference. The label adds its own caveat: because patients who could not tolerate titration were never randomised, the result may not reflect the experience of patients first starting the drug.
Does it work for blood glucose?
That is the older indication, and the Ozempic label reports it separately. In the 30-week monotherapy trial, HbA1c fell 1.4 percentage points on 0.5 mg and 1.6 on 1 mg, against 0.1 on placebo. 73% and 70% of treated patients reached an HbA1c below 7%, versus 28% on placebo.
Benefits the label puts a number on beyond weight
- Cardiovascular events. In a trial of 17,604 adults with established cardiovascular disease and obesity or overweight, the composite of cardiovascular death, non-fatal myocardial infarction or non-fatal stroke occurred in 6.5% on semaglutide versus 8% on placebo — hazard ratio 0.80. All-cause death was 4.3% versus 5.2%. Cardiovascular death alone was 2.5% versus 3%, and the label is explicit that superiority was not confirmed for that endpoint in the testing hierarchy.
- Liver disease. In noncirrhotic MASH with stage 2 to 3 fibrosis, 63% of treated patients had resolution of steatohepatitis without worsening fibrosis at week 72, versus 34% on placebo. Fibrosis improvement without worsening steatohepatitis was 37% versus 22%. This indication is approved under accelerated approval, and the label says continued approval may be contingent on a confirmatory trial.
- Body composition. The label states only that semaglutide lowers body weight with greater fat mass loss than lean mass loss. It publishes no ratio.
On how it does any of this, the label is brief: semaglutide is a GLP-1 analogue with 94% sequence homology to human GLP-1 that binds and activates the GLP-1 receptor, which is present in several brain regions involved in appetite regulation. It decreases calorie intake and delays gastric emptying. For cardiovascular risk reduction the label says plainly that the exact mechanism has not been established.
Do semaglutide tablets work?
Yes, and there are two different tablets. The 25 mg daily tablet is approved for weight reduction and produced a 13.6% weight loss at week 64 versus 2.4% on placebo, with 76.3% of patients losing at least 5% versus 31.3%. The 7 mg and 14 mg tablets are approved for type 2 diabetes and lowered HbA1c by 1.2 and 1.4 percentage points at week 26 versus 0.3 on placebo.
The interesting part is what makes them work at all. Absolute bioavailability is approximately 0.4% to 1% for the 3, 7 and 14 mg Rybelsus tablets, and 1% to 2% for the 1.5, 4 and 9 mg Ozempic tablets and the 25 mg Wegovy tablet. Over 99% of an oral dose never reaches the bloodstream. The two sets of strengths are not a weak and a strong version of the same thing — the label reports no clinically significant difference in steady-state exposure between 3, 7 and 14 mg of Rybelsus and 1.5, 4 and 9 mg of Ozempic tablets, because they are different formulations. All of them are co-formulated with salcaprozate sodium (SNAC), an absorption enhancer, and absorption occurs predominantly in the stomach.
That is why the administration rules are unusually strict, and they are dosing instructions rather than etiquette — the label reports that absorption was higher with 50 mL of water than with 240 mL, and higher after a longer post-dose fast. The label requires: on an empty stomach in the morning, with water only and no more than 4 ounces of it, swallowed whole, and at least 30 minutes before any food, drink or other oral medication.
Does compounded semaglutide work?
That is the honest state of the evidence, and it is a different claim from “it does not work”. If a compounded product genuinely contains semaglutide base at the labelled concentration, the molecule is the same molecule and the pharmacology is the pharmacology. The problem is that none of those ifs is verified by anyone before the product is sold.
The FDA states it directly: compounded drugs are not FDA approved, which means the agency does not review compounded drugs for safety, effectiveness or quality before they are marketed.
Three further facts are worth having straight:
- The shortage that permitted mass compounding is over. The FDA declared the semaglutide shortage resolved on 21 February 2025 and the tirzepatide shortage resolved on 19 December 2024. Enforcement discretion for 503A pharmacies compounding semaglutide ran to 22 April 2025, and for 503B outsourcing facilities to 22 May 2025.
- Salt forms are not the same active ingredient. Different drug The FDA states that salt forms including semaglutide sodium and semaglutide acetate are different active ingredients than are used in the approved drugs. A product sold as “semaglutide sodium” is not the substance any of the trials above studied.
- Harm is being reported. As of 31 May 2026 the FDA had received 990 reports of adverse events associated with compounded semaglutide and more than 730 associated with compounded tirzepatide. It has also received multiple reports of adverse events, some requiring hospitalisation, that may be related to dosing errors with compounded injectable semaglutide.
Dosing errors are the failure mode this site exists to reduce: a compounded vial arrives as a powder with a concentration that is whatever the compounder chose, and the arithmetic from milligrams to syringe units is done by the patient. Semaglutide dosage calculator · How to reconstitute a peptide.
Whether a compounded product is an appropriate option for any particular person is a question for a clinician and a pharmacist, not for a calculator.
Related
- Semaglutide side effects — the same label, read for the safety tables instead of the efficacy ones.
- How long semaglutide takes to work — the week 68 result above, and why nothing is published about week 4.
- Is semaglutide a peptide? — the structure behind the once-weekly dosing.
- Semaglutide to tirzepatide conversion — why no milligram equivalence exists.