History

Tesofensine (NS2330) was originally developed by NeuroSearch (Denmark) for neurodegenerative disease but was dropped for limited efficacy in Alzheimer's and Parkinson's; the weight loss seen as a side effect redirected it to obesity. Rights passed to Saniona, a 2014 NeuroSearch spin-out, which in February 2016 licensed Mexico/Argentina rights to Medix. Medix later ran a Phase 3 obesity program in Mexico, and in February 2023 COFEPRIS's technical committee issued a favorable but non-binding technical opinion; as of the most recent public Saniona/Medix updates (late 2024), the Mexican application had still not received final marketing approval.

Tesofensine is an experimental weight-loss drug with a genuinely large short-term effect in one mid-size trial — and a long list of reasons to be cautious. The single most important thing to understand is what it is: tesofensine is a small molecule, an oral triple monoamine reuptake inhibitor, from the phenyltropane chemical family. It is not a peptide, not a hormone, and not in the same class as the GLP-1 drugs it is often compared to. It has never been approved by the FDA, the EMA, or (as of mid-2026) Mexico’s COFEPRIS, and it is banned in sport as a stimulant. This page is educational and harm-reduction oriented and contains no dosing, cycles, or sourcing information.

What it is

Tesofensine (code NS2330) is a small-molecule oral triple monoamine reuptake inhibitor: it blocks the presynaptic reuptake of noradrenaline, dopamine, and serotonin, raising synaptic levels of all three. Chemically it belongs to the phenyltropane family. To be unambiguous — it is not a peptide, not a hormone, and not a growth factor.

The effect studied in obesity is primarily appetite suppression, with a possible modest increase in resting energy expenditure. Preclinical rat work attributes the appetite suppression largely to indirect stimulation of α1-adrenoceptor and dopamine D1 receptor pathways (Axel et al., Neuropsychopharmacology 2010). It was first developed by NeuroSearch for Parkinson’s and Alzheimer’s disease, where it failed for lack of efficacy; the weight loss observed as a “side effect” is what redirected it to obesity research. Tesomet is a separate, proprietary fixed-dose combination of tesofensine plus metoprolol (a beta-1 blocker added specifically to blunt the cardiovascular effects).

The claims

Tesofensine is promoted — largely in grey-market and “research chemical” weight-loss circles — as a powerful appetite suppressant capable of producing weight loss comparable to or beyond approved obesity drugs. The kernel of truth behind the hype is one Phase 2b trial (below) in which it produced placebo-subtracted weight loss in the 9–11% range at higher doses, which is genuinely large for a single agent. The leap that is not supported is the implication that this is proven, approved, or shown to beat modern GLP-1/GIP drugs — none of which is true.

What the evidence actually shows

The honest summary: there is one mid-size Phase 2 obesity trial with a striking result, a couple of small supporting human studies, and a company-reported (but not peer-reviewed) Phase 3 dataset. That is preliminary human evidence, not the kind of large, replicated, long-term efficacy-and-safety base that supports approved obesity drugs.

TIPO-1 (Phase 2b — the key trial): Astrup et al., Lancet 2008 (NCT00394667). A randomized, double-blind, placebo-controlled trial in 203 obese adults over 24 weeks plus diet, across 5 Danish/European obesity centers. Placebo-subtracted mean weight loss was roughly 4.5% / 9.2% / 10.6% at 0.25 / 0.5 / 1.0 mg; the authors favored the 0.5 mg dose for a better efficacy/tolerability balance. This is a large effect for a single agent — but it is one mid-size Phase 2 trial, it predates the GLP-1/GIP era, and head-to-head data versus semaglutide or tirzepatide do not exist.
Mechanistic/metabolic human study: Sjödin et al., Int J Obes 2010, examined tesofensine’s effects on energy metabolism and appetite in overweight and moderately obese men — supporting the appetite-suppression mechanism.
Tesomet in hypothalamic obesity (Phase 2): Huynh et al., Eur J Endocrinol 2022 (NCT03845075). A small (n=21), 24-week randomized controlled trial showing roughly −6.3% to −6.8% placebo-subtracted weight change; notably, with metoprolol co-administration, no significant heart-rate or blood-pressure increase was seen. Encouraging but preliminary given the small sample.
Medix Phase 3 (obesity): described in company readouts as meeting endpoints, but with no confirmed peer-reviewed full publication. Treat the Phase 3 efficacy as company-reported pending publication.

Legal and regulatory status

Not approved by any major regulator. Tesofensine has not been approved by the FDA or EMA; US status is investigational (IND), and it has never been marketed in the US or EU.

Mexico (COFEPRIS): Medix ran a Phase 3 program and filed a new drug application. In February 2023, COFEPRIS’s technical committee issued a favorable but non-binding technical opinion — explicitly not a marketing authorization. Per the most recent public Saniona/Medix updates (November 2024, with a planned dossier resubmission around February 2025), tesofensine had not received final COFEPRIS marketing approval; the application was confirmed not yet approved. There is no reliable confirmation of an approved-and-launched product or brand name, so any “approved in Mexico” claim should be treated as unconfirmed or false.

Tesomet (tesofensine + metoprolol) was Saniona’s proprietary program for hypothalamic obesity and Prader-Willi syndrome. Those Phase 2b programs were voluntarily paused — reportedly for funding reasons, not safety or efficacy — as part of a 2022 corporate restructuring. Tesomet is also investigational and unapproved.

Anti-doping (WADA). Tesofensine is prohibited. On the 2025 WADA Prohibited List (effective 1 Jan 2025), tesofensine (along with midodrine) was added as a named example under S6 Stimulants, prohibited in-competition. USADA specifically flagged it as increasingly appearing in dietary supplements. As a stimulant it is a “specified” substance, but it is banned — a stricter status than the GLP-1 agonists, which sit on the WADA Monitoring Program and are not prohibited. So tesofensine is banned as a stimulant (S6), not as a hormone or growth factor.

Bottom line on status: research/trial-grade everywhere, with no major-regulator approval as of mid-2026. It is nonetheless sold widely as a “research chemical” / grey-market weight-loss product, which is unapproved and unregulated.

Safety

The most consistently reported adverse effects in obesity trials are dry mouth, headache, insomnia and other sleep disturbance, nausea, constipation or diarrhea, and mood/psychiatric effects.

The central concern is cardiovascular. As monotherapy, tesofensine raised heart rate and blood pressure dose-dependently; the Lancet trial and accompanying commentary explicitly flagged the BP/HR increases and possible psychiatric effects. This monoaminergic/sympathomimetic profile is the same class problem that led to the withdrawal of sibutramine. The Tesomet (with metoprolol) approach was specifically designed to offset the cardiovascular effects, and the small Phase 2 did not show a significant HR/BP change — but long-term cardiovascular and psychiatric safety in large populations is not established.

Finally, grey-market or “research-grade” tesofensine carries the added, undocumented risks of unverified identity, purity, and dosing — on top of a drug whose long-term safety is already unproven.

Bottom line

Tesofensine is an investigational small-molecule triple monoamine reuptake inhibitor — emphatically not a peptide — with a genuinely impressive short-term weight-loss signal in one mid-size Phase 2 trial (TIPO-1) and a couple of small supporting studies. But that is the whole human evidence base: it is preliminary, it predates the modern GLP-1/GIP era, there is no head-to-head data, and the larger Phase 3 dataset remains company-reported and unpublished. It is not approved by the FDA, EMA, or (as of mid-2026) COFEPRIS, its monoaminergic/sympathomimetic profile raises the same cardiovascular and psychiatric concerns that sank sibutramine, and it is banned in sport as an S6 stimulant. The version sold online as a “research chemical” adds unverified identity, purity, and dosing on top of an already-unproven drug.

Evidence grade: Preliminary human.