Key takeaways
- Tesofensine is a small-molecule drug, not a peptide. It blocks the reuptake of three brain chemicals: noradrenaline, dopamine and serotonin.
- Its main obesity trial, a 24-week phase 2 study from 2008, showed meaningful weight loss, but the journal later attached an expression of concern to that paper.
- Raised heart rate is the recurring safety question, which is why the developer paired it with the beta blocker metoprolol.
- It is not FDA-approved, and as of the latest public updates it is not approved in Mexico either.
Tesofensine shows up on a lot of research-chemical sites next to peptides, so people assume it is one. It isn't. It's a conventional small-molecule drug that was first tested in Parkinson's and Alzheimer's disease trials in the early 2000s before being developed for weight loss 12.
That history matters. Tesofensine has more human data than most compounds on this site, yet after nearly two decades it still has no approval anywhere we could confirm. Here's what the evidence actually says.
A triple reuptake inhibitor, not a peptide
Tesofensine blocks the reuptake of noradrenaline, dopamine and serotonin. More of those signals stay active in the brain, which appears to blunt appetite and may nudge energy use up. Our site entry rates the evidence at level 3 of 5 and lists its half-life as not established.
Because it works like a stimulant, the World Anti-Doping Agency lists it under S6 stimulants, banned in competition 3. A 2026 anti-doping study found it could be detected in urine for up to about 500 hours after a single dose in some volunteers 3.
The 2008 Lancet trial
The trial most people cite is a Danish phase 2 study led by Arne Astrup 4. It enrolled 203 adults with obesity, put everyone on a calorie-restricted diet, and randomly assigned them to one of three tesofensine doses or a placebo for 24 weeks. The trial was registered as NCT00394667 5.
Placebo plus diet produced an average weight loss of 2.0%. The three tesofensine groups lost 4.5%, 9.2% and 10.6% 4. About 79% of participants finished the study. The most common side effects were dry mouth, nausea, constipation, diarrhoea and insomnia 4.
The authors were clear that these results "need confirmation in phase III trials" 4. That caveat is still the honest summary.
The expression of concern
In April 2013 The Lancet published an expression of concern about the 2008 paper 6. An expression of concern is a journal's formal warning that it has questions about a published study. It is not a retraction.
We couldn't open the full text of the notice, so we can't tell you exactly what the concern was. PubMed lists it alongside the original paper 6. If you see that trial quoted as settled proof, keep that flag in mind.
Heart rate and blood pressure
Drugs that boost noradrenaline tend to speed the heart up, and tesofensine is no exception. In the 2008 trial, the middle dose raised resting heart rate by 7.4 beats per minute compared with placebo 4. The two lower doses did not significantly raise blood pressure 4.
Rat studies from the original developer showed the same pattern: tesofensine raised heart rate and blood pressure, and adding the beta blocker metoprolol blocked those effects without blunting the drop in food intake 7.
That led to "Tesomet," a fixed combination of tesofensine and metoprolol. In a small trial of 21 adults with hypothalamic obesity (weight gain caused by damage to the brain's appetite centre), Tesomet produced an extra 6.3% weight loss versus placebo over 24 weeks, with no significant difference in heart rate or blood pressure 8. Sleep problems, dry mouth and headache were more common on Tesomet, and one person stopped because of worsened anxiety 8.
That's a promising signal, but it's 21 people. Two larger follow-up Tesomet trials in hypothalamic obesity and Prader-Willi syndrome were registered and then withdrawn before enrolling anyone 910.
Mexico: filed, but not approved
You'll often read that tesofensine is "approved in Mexico." We couldn't verify that.
Mexican drugmaker Medix, which licenses tesofensine from the Danish company Saniona, ran its own phase 3 program in Mexico. According to a Saniona press release, it enrolled 372 patients and produced about 10% average weight loss over 24 weeks 11. We couldn't find those results in a peer-reviewed journal, so treat them as company-reported.
In November 2024 Saniona announced that Medix had not received approval from COFEPRIS, Mexico's drug regulator 11. In February 2025 Saniona said Medix had resubmitted a revised application of about 20,000 pages 12. We found no public decision after that.
FDA status
Tesofensine is not FDA-approved for any use. In December 2025 the FDA sent a warning letter to Darmerica, a Florida supplier of bulk drug ingredients. The letter listed tesofensine among ingredients that aren't eligible for use in human drug compounding, and said the products were misbranded because their labeling lacked adequate directions for use 13.
In plain terms, a US pharmacy can't legally compound it, and products sold online aren't regulated medicines. The anti-doping study above noted tesofensine has been sold online as a "dietary supplement" 3.
The bottom line
Tesofensine has real human trial data showing weight loss, which puts it ahead of many compounds marketed alongside it. But its key trial carries an expression of concern, heart rate is a consistent issue, and the phase 3 data from Mexico haven't been peer-reviewed. It isn't approved in the US, and we found no confirmed approval in Mexico.
This is educational information, not medical advice.
Sources
- NS 2330 in early Parkinson's disease (NCT00148486) — ClinicalTrials.gov. https://clinicaltrials.gov/study/NCT00148486
- An evaluation of three doses of NS 2330 in patients with mild to moderate dementia of the Alzheimer's type (NCT00153010) — ClinicalTrials.gov. https://clinicaltrials.gov/study/NCT00153010
- Investigations into the metabolism and elimination of tesofensine in human urine — Drug Testing and Analysis, 2026. https://pubmed.ncbi.nlm.nih.gov/42320973/
- Effect of tesofensine on bodyweight loss, body composition, and quality of life in obese patients: a randomised, double-blind, placebo-controlled trial — The Lancet, 2008. https://pubmed.ncbi.nlm.nih.gov/18950853/
- Effect of Tesofensine on Weight Reduction in Patients With Obesity (NCT00394667) — ClinicalTrials.gov. https://clinicaltrials.gov/study/NCT00394667
- Expression of concern: effect of tesofensine on bodyweight loss, body composition, and quality of life in obese patients — The Lancet, April 2013. https://pubmed.ncbi.nlm.nih.gov/23561987/
- Anti-hypertensive treatment preserves appetite suppression while preventing cardiovascular adverse effects of tesofensine in rats — Obesity, 2013. https://pubmed.ncbi.nlm.nih.gov/23784901/
- Randomized controlled trial of Tesomet for weight loss in hypothalamic obesity — European Journal of Endocrinology, 2022. https://pubmed.ncbi.nlm.nih.gov/35294397/
- Study of Tesomet with open-label extension in subjects with hypothalamic obesity (NCT05147415, withdrawn) — ClinicalTrials.gov. https://clinicaltrials.gov/study/NCT05147415
- Study of Tesomet with open-label extension in subjects with Prader-Willi syndrome (NCT05198362, withdrawn) — ClinicalTrials.gov. https://clinicaltrials.gov/study/NCT05198362
- Mexican application for tesofensine not yet approved — Saniona press release, November 6, 2024. https://www.inderes.fi/en/releases/mexican-application-for-tesofensine-not-yet-approved
- Medix has resubmitted tesofensine application to COFEPRIS — Saniona press release, February 20, 2025. https://www.inderes.fi/en/releases/medix-has-resubmitted-tesofensine-application-to-cofepris
- Warning letter: Darmerica, LLC (716152) — U.S. Food and Drug Administration, December 8, 2025. https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/darmerica-llc-716152-12082025
