Peptifact

Tesofensine Results: What the Trials Measured, the Journal Notice on the Main One, and the Phase 3 Nobody Has Published

Tesofensine produced 4.5–10.6% weight loss over 24 weeks in its one published obesity trial, against 2.0% on diet and placebo. That trial has carried an expression of concern from The Lancet since 2013, and the Phase 3 its developer's partner says it completed in Mexico has never been published. Every result on record, and what each one can and cannot show.

Robert F · Edited by Caroline S · Published 2026-10-26

Illustration: An open insulated shipping box with cool blue gel packs and an empty glass vial on a grey foam insert.
Illustration

Tesofensine is an oral drug that blocks the reuptake of noradrenaline, dopamine and serotonin. It was developed for Parkinson's and Alzheimer's disease, failed there, and was turned into an obesity drug because people in those trials lost weight. It is not a peptide — it is a small molecule taken as a tablet — but it is sold alongside peptides by research vendors, which is why it appears here.

This page answers the question people search as "tesofensine results" or "before and after": what the trials measured, in whom, and how reliable each figure is. The doses themselves, and why heart rate is the through-line of the record, are on our tesofensine dosage page. Nothing here is a recommendation.

The results, trial by trial

Every published efficacy result, read from the abstracts on 26 October 2026:

Study Who Duration Arms Result
Astrup 2008, The Lancet (NCT00394667) 203 adults with obesity (BMI 30–40), energy-restricted diet 24 weeks Placebo · 0.25 · 0.5 · 1.0 mg daily Weight loss 2.0% · 4.5% · 9.2% · 10.6%
Astrup 2008, Obesity (pooled) 968 patients with Parkinson's or Alzheimer's, no diet 14 weeks Placebo · 0.125 · 0.25 · 0.5 · 1.0 mg Weight change +0.5% · −0.5% · −0.9% · −1.8% · −2.8%
same, obese subgroup obese patients within those trials 14 weeks as above Lost ≥5%: 2.1% · 8.2% · 14.1% · 20.9% · 32.1%
Huynh 2022, Eur J Endocrinol 21 adults with hypothalamic obesity (16 women), diet counselling 24 weeks Tesomet (0.5 mg + 50 mg metoprolol) vs placebo −6.3% over placebo (95% CI −11.3 to −1.3); ≥5% loss in 8/13 vs 1/8

Three things in that table matter more than the headline numbers.

The diet does a lot of the work in the large effect. The 24-week obesity trial put everyone on an energy-restricted diet; the 14-week neurology trials did not, and at the same 1.0 mg dose the average loss was 2.8% rather than 10.6%. The populations also differed — older, ill, and mostly not obese — so the gap is not a clean measure of the diet's share, but a reader comparing a social-media result with 10.6% should know which conditions produced that figure.

One in five people did not finish. In the Lancet trial, 161 of 203 participants (79%) completed 24 weeks. The results were analysed by modified intention to treat — everyone with a measurement after at least one dose — so dropouts are included, but how their missing weeks were handled is in the full paper, not the abstract.

The newest trial is of a different product. Tesomet adds the beta-blocker metoprolol, which the developer paired with tesofensine to counter the heart-rate rise. It was tested in hypothalamic obesity, a rare condition caused by brain injury or tumours, in 21 people. Its result says something about that combination in that condition; it does not extend the plain-tesofensine record.

The notice attached to the main trial

The 2008 Lancet trial is the source of nearly every "tesofensine doubles weight loss" claim, including its own authors' line that 0.5 mg "might have the potential to produce a weight loss twice that of currently approved drugs". In April 2013 The Lancet published an expression of concern about that paper (Lancet 2013;381:1167). In July 2013 the six trial authors replied in the same journal under the title "Under-reporting of adverse effects of tesofensine" (Lancet 2013;382:127).

We could not open the text of either item — The Lancet's page refused an automated request — so we report only what the indexed records show: the concern exists, it is linked to the 2008 trial in PubMed, the authors' reply is framed around the reporting of side effects, and the paper has not been retracted. A 2009 evaluation of the same trial (Doggrell 2009) had already noted increases in blood pressure and heart rate and a possible increase in psychiatric adverse effects, including depressed mood. Readers weighing the efficacy figures should weigh them as figures from a trial whose safety reporting the publishing journal itself flagged.

What "before and after" can and cannot show

The trials measured weight as a percentage of starting weight at fixed time points. They did not measure what before-and-after posts claim to show. Specifically:

  • Body composition. The Lancet trial's title includes body composition, but its abstract gives no fat-mass or lean-mass figures, and we did not read the full paper. We do not report a fat-versus-muscle split for tesofensine.
  • What happens after stopping. No published trial reports weight after tesofensine was withdrawn. The two open-label extension studies Saniona registered — in Prader-Willi syndrome and hypothalamic obesity — are both listed as withdrawn on ClinicalTrials.gov.
  • Results with a research product. Every figure above came from pharmaceutical-grade tablets of known strength. A powder or capsule bought online is a different thing to measure, and its content is unverified.
  • Results in people without obesity. The large effect was measured in adults with a BMI of 30 to 40. Nobody has published a trial of tesofensine for modest weight loss in people who are not obese.

The heart rate is the one cost that travels with every efficacy figure: in the Lancet trial, 0.5 mg raised resting heart rate by 7.4 beats per minute over placebo, and in the neurology trials the rise was dose-related from 2.1 to 6.8 beats per minute. The full table is on the dosage page.

The Phase 3 that was run but not published

ClinicalTrials.gov lists 13 tesofensine studies from three sponsors — Boehringer Ingelheim, NeuroSearch and Saniona — every one Phase 1 or Phase 2, two withdrawn (registry API, read 26 October 2026). That is why the record looks as if the drug never reached Phase 3.

It did, in Mexico. Saniona's own tesofensine page states that "Saniona's partner Medix completed a Phase 3 program studying tesofensine (0.25 and 0.50 mg daily) in people with obesity", that the study "confirmed the compelling efficacy and favorable safety profile", and that Medix "has submitted a new drug application to the Mexican food and drug administration, COFEPRIS". The company's history page records that it licensed the Mexican and Argentine rights to Medix in 2016 and that in 2023 "Saniona's partner Medix receives a favorable opinion for tesofensine".

What does not exist, as of 26 October 2026: any peer-reviewed publication of that Phase 3 (a PubMed search for tesofensine returns 56 records and none is a Phase 3 report), any registry entry for it on ClinicalTrials.gov, or any document we could open confirming a final marketing authorisation in Mexico. The sponsor's description of its own unpublished trial as "compelling" is a claim, not a result a reader can check. This is the single largest gap in the tesofensine record: the trial most likely to answer whether the 2008 figures hold up is the one nobody outside the companies can read.

Sold as a supplement, tested for in sport

A 2026 study from the German Sport University's doping-control laboratory (Krug 2026, Drug Testing and Analysis) states that tesofensine, "although still under regulatory review, has been marketed online as a dietary supplement promoted for weight management". The authors gave six volunteers a single 483 µg dose of such a product and could detect tesofensine metabolites in urine for up to 500 hours — about three weeks — with peak concentrations reached anywhere from 4 to 46 hours. Tesofensine sits on the World Anti-Doping Agency's list under S6 stimulants, prohibited in competition only, according to the paper.

FDA's adverse-event database held three reports naming tesofensine when queried through openFDA on 26 October 2026 — a number that reflects how rarely it is reported in the United States, not how often it causes harm.

How tesofensine compares

For readers comparing it with the GLP-1 drugs that now dominate obesity treatment, the honest comparison is between records, not percentages: semaglutide and tirzepatide were approved on Phase 3 programmes with thousands of participants and published cardiovascular outcomes; tesofensine's published efficacy rests on one 203-person trial with a journal notice attached. GLP1 Ledger covers the approved drugs' trial results in its Mounjaro weight-loss page. Peptide Lexicon explains, for the peptides that tesofensine is sold beside, what separates a peptide from a protein. For other compounds sold for weight loss with thinner records, see our AOD-9604 results page.

What is not established

  • Whether the 2008 results replicate. The only confirmatory trial reported to exist is unpublished.
  • What the 2013 expression of concern covered in detail. Its text was not available to us.
  • Weight regain after stopping, and long-term safety beyond 24 weeks in obesity.
  • Effects in people without obesity, or with any product other than pharmaceutical tablets.
  • Its regulatory status in Mexico beyond the 2023 favourable opinion its developer reports.

Any decision about a weight-loss medicine belongs with a prescribing clinician who can weigh it against heart rate, blood pressure and mental-health history.

Sources and dates

  • Astrup A, Madsbad S, Breum L, Jensen TJ, Kroustrup JP, Larsen TM. Effect of tesofensine on bodyweight loss, body composition, and quality of life in obese patients: a randomised, double-blind, placebo-controlled trial. Lancet. 2008;372(9653):1906–13. PMID 18950853; NCT00394667 — abstract read 26 October 2026.
  • The Lancet. Expression of concern for the above. Lancet. 2013;381(9873):1167. PMID 23561987 — indexed record read 26 October 2026 (full text not openable).
  • Astrup A et al. Under-reporting of adverse effects of tesofensine. Lancet. 2013;382(9887):127. PMID 23849924 — indexed record read 26 October 2026.
  • Astrup A et al. Weight loss produced by tesofensine in patients with Parkinson's or Alzheimer's disease. Obesity. 2008;16(6):1363–9. PMID 18356831 — abstract read 26 October 2026.
  • Huynh K et al. Randomized controlled trial of Tesomet for weight loss in hypothalamic obesity. Eur J Endocrinol. 2022;186(6):687–700. PMID 35294397 — abstract read 26 October 2026.
  • Doggrell SA. Tesofensine — a novel potent weight loss medicine. Expert Opin Investig Drugs. 2009;18(7):1043–6. PMID 19548858.
  • Krug O, Thomas A, Thevis M. Investigations into the metabolism and elimination of tesofensine in human urine. Drug Test Anal. 2026;18(9):1163–73. PMID 42320973 — abstract read 26 October 2026.
  • Saniona, tesofensine pipeline page (dated 13 December 2023) and company history page — read 26 October 2026.
  • ClinicalTrials.gov API v2, intervention "tesofensine": 13 studies, Phase 1–2 only, two withdrawn — read 26 October 2026. PubMed search "tesofensine": 56 records — 26 October 2026. openFDA drug adverse events, "tesofensine": 3 reports — 26 October 2026.

Frequently asked questions

Does tesofensine work for weight loss?

In its one published obesity trial, people on 0.5 mg lost 9.2% of body weight over 24 weeks on a calorie-restricted diet, against 2.0% on diet and placebo, and 1.0 mg gave 10.6%. That trial is the core of the evidence, it has carried an expression of concern from The Lancet since 2013, and the confirmatory Phase 3 its developer's partner says it ran in Mexico has not been published. So the efficacy signal is real in the published data but rests on a narrower and more disputed record than its headline suggests.

How much weight do people lose on tesofensine?

The published figures are 4.5% (0.25 mg), 9.2% (0.5 mg) and 10.6% (1.0 mg) over 24 weeks with a diet, against 2.0% on placebo, in 203 adults with obesity. Without a diet, in older patients with Parkinson's or Alzheimer's disease, losses over 14 weeks were 0.5% to 2.8%. Individual before-and-after figures posted online are not trial results and cannot be checked.

How long does tesofensine take to work?

The trials report weight at the end of fixed periods — 14 and 24 weeks — rather than an onset time. The 14-week trials already showed a dose-related difference from placebo, and the 24-week trial measured its primary result at week 24. No published trial reports what happens to weight after tesofensine is stopped.

Is tesofensine approved anywhere?

It is not approved by the US FDA or the European Medicines Agency. Saniona says its Mexican partner Medix submitted a new drug application to COFEPRIS and received a favourable opinion in 2023; we found no document confirming a final marketing authorisation, so its status in Mexico is reported here as unconfirmed.

Why does the main tesofensine trial have an expression of concern?

The Lancet published an expression of concern about the 2008 trial in April 2013. The notice's full text was not available to us, but the trial authors' published reply that July is titled 'Under-reporting of adverse effects of tesofensine', which places the concern on how side effects were reported rather than on the weight figures. The paper has not been retracted.