# Tesofensine Tesofensine has no approved use in the US, and FDA says pharmacies may not use it to make drugs. The evidence grade is moderate-human. A trial in obese adults found weight loss over 24 weeks. But a journal later raised concern about that trial, and no larger trial has results in our sources. Status checked: 2026-10-26. Last verified: 2026-10-26. Primary source: https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/darmerica-llc-716152-12082025 This page has not been individually reviewed by a clinician. Information, not medical advice. | Fact | Value | Tier | Checked | Source | |---|---|---|---|---| | Also called | NS-2330 | peer-reviewed | 2026-10-26 | [source](https://pubmed.ncbi.nlm.nih.gov/42320973/) | | Class | non-peptide | peer-reviewed | 2026-10-26 | [source](https://pubmed.ncbi.nlm.nih.gov/19777399/) | | Regulatory status | no-approved-use | primary | 2026-10-26 | [source](https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/darmerica-llc-716152-12082025) | | Status source read | 2026-10-26 | primary | 2026-10-26 | [source](https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/darmerica-llc-716152-12082025) | | Evidence grade | moderate-human | our assessment | 2026-10-26 | [source](https://peptideindex.ai/methodology#evidence-grade) | ## Name Tesofensine Source: https://pubmed.ncbi.nlm.nih.gov/19777399/ ## Summary A pill that blocks the brain from taking back three chemical messengers. It was tested as a drug for obesity. Source: https://pubmed.ncbi.nlm.nih.gov/19777399/ ## Short answer Tesofensine has no approved use in the US, and FDA says pharmacies may not use it to make drugs. The evidence grade is moderate-human. A trial in obese adults found weight loss over 24 weeks. But a journal later raised concern about that trial, and no larger trial has results in our sources. Source: https://peptideindex.ai/methodology#short-answer ## Known risks - In the main trial, tesofensine raised heart rate. Dry mouth, nausea, constipation, diarrhea and trouble sleeping were common [^5]. - A 2009 review says heart rate rose more as the amount given rose. Blood pressure rose at the highest amount tested [^12]. - In a small trial of tesofensine with metoprolol, one person's anxiety got worse, and they stopped. Sleep problems, dry mouth and headache were more common than on a dummy pill [^9]. - FDA found that a company that sent tesofensine to pharmacies did not check its suppliers well. FDA said the drug ingredients it handled were adulterated [^1]. - A news report on the main trial says people lost lean body mass, not only fat [^16]. Source: https://pubmed.ncbi.nlm.nih.gov/18950853/ ## What nobody knows yet - In 2013, the journal that published the main trial raised an expression of concern about it. The record we hold does not say why [^6]. - The trial's authors said larger, late-stage trials must confirm their results. Our sources hold no results from such trials [^5]. - Nobody knows if the weight stays off. In one trial, the feeling of fullness faded over time and went away after people stopped [^8]. - The longest controlled trials in our sources lasted 24 weeks. Nobody knows what years of use do [^5] [^9]. - How tesofensine leads to weight loss in people is unclear. The brain dopamine results come from rats [^7] [^10] [^11]. Source: https://pubmed.ncbi.nlm.nih.gov/18950853/ ## What it is Tesofensine is a drug taken by mouth [^12]. It blocks the brain from taking back three chemical messengers: noradrenaline, dopamine and serotonin [^5]. Chemical messengers carry signals between nerve cells. It is also called NS-2330 [^17]. A drug company first tested it for brain diseases such as Alzheimer's disease [^12] [^16]. It did not help them, but some people lost weight they did not mean to lose [^12]. The company then tested it as a pill for obesity [^12]. A later company tested it combined with another drug, metoprolol, for rare kinds of obesity [^3] [^9]. One of these is hypothalamic obesity: fast weight gain after injury to the hypothalamus, a part of the brain [^9]. Source: https://pubmed.ncbi.nlm.nih.gov/19777399/ ## Where it stands legally Tesofensine has no approved use in the US: FDA says it is not eligible for use in pharmacy compounding [^1]. That means no pharmacy may lawfully make drugs from it. It does not mean a seller may offer it for people, and FDA says a company that sent it to pharmacies broke federal law [^1]. Checked 26 October 2026. A pharmacy may make a drug from a bulk ingredient only in three cases [^2]. The ingredient has an official quality standard, is part of an FDA-approved drug, or is on a list FDA keeps [^2]. FDA's 2025 letter puts tesofensine among ingredients that are not eligible [^1]. In 2021, FDA gave orphan drug status to tesofensine combined with metoprolol [^3] [^4]. Orphan status marks a drug being developed for a rare disease [^3]. The two uses were Prader-Willi syndrome and hypothalamic obesity [^3] [^4]. That is not approval: both FDA records say the combination is not approved for these uses [^3] [^4]. A 2009 review says FDA backed plans for larger obesity trials of tesofensine [^12]. A 2008 news report says its maker was seeking approval in the US and Europe [^16]. Backing a trial plan, or seeking approval, is not approval. Source: https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/darmerica-llc-716152-12082025 ## What the evidence shows The evidence grade is moderate-human: one controlled trial in obese adults, published in full, found more weight loss than a dummy pill over 24 weeks [^5]. That trial later drew an expression of concern from its journal, so the main result is in question [^6]. In that trial, 203 obese adults in Denmark went on a low-calorie diet [^5]. They took tesofensine or a dummy pill for 24 weeks [^5]. People on tesofensine lost between 4.5% and 10.6% of their weight, against 2.0% on the dummy pill [^5]. The authors said larger trials must confirm the results [^5]. In 32 overweight or obese men, two weeks of tesofensine cut appetite [^7]. They lost 1.8 kg more than men on a dummy pill [^7]. In another trial, tesofensine made people feel fuller, but the effect faded as weight came off [^8]. In 21 adults with hypothalamic obesity, tesofensine with metoprolol led to 6.3% more weight loss than a dummy pill over 24 weeks [^9]. That trial was small, and its main goal was to look for harms [^9]. In obese rats, tesofensine cut food intake and weight and changed brain dopamine [^10] [^11]. When the rats stopped it, they ate more and gained weight again [^11]. These are animal results, not results in people. Source: https://pubmed.ncbi.nlm.nih.gov/18950853/ ## Legitimate ways to get it No pharmacy may lawfully make tesofensine, and FDA has approved no use of it [^1] [^3]. There is no legal route to it in the US today. The three studies of it in our sources took place in Denmark and ended by 2020 [^13] [^14] [^15]. Any open trial appears in the trials block below, with the date the official registry was last checked. Source: https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/darmerica-llc-716152-12082025 ## How people are getting it anyway This section describes what happens and is not a recommendation. One way of getting tesofensine shows up in federal records: pharmacies that make it although the law does not allow it [^1]. In December 2025, FDA sent a warning letter to a Florida company that sells drug ingredients [^1]. FDA says the company sent tesofensine to pharmacies that wanted to make drugs from it [^1]. FDA says tesofensine may not be used that way, so the company broke federal law [^1]. FDA also found the company did not check its suppliers well [^1]. It said the drug ingredients the company handled were adulterated [^1]. Adulterated means not made under the quality rules the law requires [^1]. Our sources hold no federal record of other ways tesofensine reaches people. Source: https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/darmerica-llc-716152-12082025 ## Access routes Source: https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/darmerica-llc-716152-12082025 ### None Detail: There is no legal route to tesofensine in the US today. FDA says pharmacies may not use it to make drugs. Source: https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/darmerica-llc-716152-12082025 ## Unofficial channels Source: https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/darmerica-llc-716152-12082025 ### Compounding outside the rules What it is: Made by a pharmacy from bulk tesofensine sent by a drug ingredient company, although it may not be used in pharmacy compounding. Legal position: FDA says tesofensine is not eligible for use in pharmacy compounding. A company that sends it to pharmacies for that use breaks federal law. (source: https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/darmerica-llc-716152-12082025) Documented risks: - FDA found that a company that sent tesofensine to pharmacies did not check its suppliers well, and said its drug ingredients were adulterated. (source: https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/darmerica-llc-716152-12082025) - In a trial in obese adults, tesofensine raised heart rate, and dry mouth, nausea and trouble sleeping were common. (source: https://pubmed.ncbi.nlm.nih.gov/18950853/) Enforcement: - 2025-12-08: FDA warning letter to a Florida drug ingredient company that sent tesofensine and other ingredients to compounding pharmacies. (source: https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/darmerica-llc-716152-12082025) Source: https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/darmerica-llc-716152-12082025 ## Recruiting trials Snapshot date: 2026-10-26. A listing is not a recommendation. Trials have strict eligibility rules. Talk to your doctor and read the official record. None in this snapshot. Source: https://clinicaltrials.gov/api/v2/studies?query.intr=tesofensine&filter.overallStatus=RECRUITING%2CNOT_YET_RECRUITING&pageSize=50&sort=StartDate%3Adesc&countTotal=true&fields=NCTId%2CBriefTitle%2COverallStatus%2CPhase%2CLeadSponsorName%2CStartDate%2CLocationCountry%2CLocationState ## Sources Source: https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/darmerica-llc-716152-12082025 ### 1. FDA warning letter to a drug ingredient company that sent tesofensine to pharmacies, 8 December 2025 Type: regulatory Tier: primary Source: https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/darmerica-llc-716152-12082025 ### 2. FDA: bulk drug substances used in compounding under section 503A Type: regulatory Tier: primary Source: https://www.fda.gov/drugs/human-drug-compounding/bulk-drug-substances-used-compounding-under-section-503a-fdc-act ### 3. FDA orphan drug record: tesofensine plus metoprolol for Prader-Willi syndrome, designated 2021 Type: regulatory Tier: primary Source: https://www.accessdata.fda.gov/scripts/opdlisting/oopd/detailedIndex.cfm?cfgridkey=804320 ### 4. FDA orphan drug record: tesofensine plus metoprolol for hypothalamic obesity, designated 2021 Type: regulatory Tier: primary Source: https://www.accessdata.fda.gov/scripts/opdlisting/oopd/detailedIndex.cfm?cfgridkey=804220 ### 5. Tesofensine and weight loss in obese adults, a 24-week trial, 2008 Type: rct Tier: peer-reviewed Source: https://pubmed.ncbi.nlm.nih.gov/18950853/ ### 6. The Lancet: expression of concern about the 2008 tesofensine trial, 2013 Type: reference Tier: peer-reviewed Source: https://pubmed.ncbi.nlm.nih.gov/23561987/ ### 7. Tesofensine, energy use and appetite in overweight and obese men, 2010 Type: rct Tier: peer-reviewed Source: https://pubmed.ncbi.nlm.nih.gov/20479765/ ### 8. Tesofensine and the feeling of fullness over time, 2012 Type: rct Tier: peer-reviewed Source: https://pubmed.ncbi.nlm.nih.gov/21720440/ ### 9. Tesofensine with metoprolol in adults with hypothalamic obesity, 2022 Type: rct Tier: peer-reviewed Source: https://pubmed.ncbi.nlm.nih.gov/35294397/ ### 10. Tesofensine, appetite and brain dopamine in obese rats, 2013 Type: animal Tier: peer-reviewed Source: https://pubmed.ncbi.nlm.nih.gov/23932919/ ### 11. Tesofensine, food intake and dopamine receptors in obese rats, 2012 Type: animal Tier: peer-reviewed Source: https://pubmed.ncbi.nlm.nih.gov/21889317/ ### 12. Review: tesofensine as a drug for obesity, 2009 Type: reference Tier: peer-reviewed Source: https://pubmed.ncbi.nlm.nih.gov/19777399/ ### 13. ClinicalTrials.gov: tesofensine for weight loss in obesity, Denmark, started 2006 Type: reference Tier: primary Source: https://clinicaltrials.gov/study/NCT00394667 ### 14. ClinicalTrials.gov: long-term safety of tesofensine in obesity, Denmark, started 2007 Type: reference Tier: primary Source: https://clinicaltrials.gov/study/NCT00481104 ### 15. ClinicalTrials.gov: tesofensine with metoprolol in obesity after hypothalamic injury, Denmark, started 2019 Type: reference Tier: primary Source: https://clinicaltrials.gov/study/NCT03845075 ### 16. 6abc News: a Danish trial of tesofensine for obesity, 2008 Type: reference Tier: established-news Source: https://6abc.com/archive/6466750 ### 17. How the body breaks down and clears tesofensine, in six volunteers, 2026 Type: human-trial Tier: peer-reviewed Source: https://pubmed.ncbi.nlm.nih.gov/42320973/ Last verified: 2026-10-26. Sources: - https://clinicaltrials.gov/api/v2/studies?query.intr=tesofensine&filter.overallStatus=RECRUITING%2CNOT_YET_RECRUITING&pageSize=50&sort=StartDate%3Adesc&countTotal=true&fields=NCTId%2CBriefTitle%2COverallStatus%2CPhase%2CLeadSponsorName%2CStartDate%2CLocationCountry%2CLocationState - https://peptideindex.ai/methodology#evidence-grade - https://peptideindex.ai/methodology#short-answer - https://pubmed.ncbi.nlm.nih.gov/18950853/ - https://pubmed.ncbi.nlm.nih.gov/19777399/ - https://pubmed.ncbi.nlm.nih.gov/42320973/ - https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/darmerica-llc-716152-12082025 [^1]: FDA warning letter to a drug ingredient company that sent tesofensine to pharmacies, 8 December 2025 https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/darmerica-llc-716152-12082025 [^2]: FDA: bulk drug substances used in compounding under section 503A https://www.fda.gov/drugs/human-drug-compounding/bulk-drug-substances-used-compounding-under-section-503a-fdc-act [^3]: FDA orphan drug record: tesofensine plus metoprolol for Prader-Willi syndrome, designated 2021 https://www.accessdata.fda.gov/scripts/opdlisting/oopd/detailedIndex.cfm?cfgridkey=804320 [^4]: FDA orphan drug record: tesofensine plus metoprolol for hypothalamic obesity, designated 2021 https://www.accessdata.fda.gov/scripts/opdlisting/oopd/detailedIndex.cfm?cfgridkey=804220 [^5]: Tesofensine and weight loss in obese adults, a 24-week trial, 2008 https://pubmed.ncbi.nlm.nih.gov/18950853/ [^6]: The Lancet: expression of concern about the 2008 tesofensine trial, 2013 https://pubmed.ncbi.nlm.nih.gov/23561987/ [^7]: Tesofensine, energy use and appetite in overweight and obese men, 2010 https://pubmed.ncbi.nlm.nih.gov/20479765/ [^8]: Tesofensine and the feeling of fullness over time, 2012 https://pubmed.ncbi.nlm.nih.gov/21720440/ [^9]: Tesofensine with metoprolol in adults with hypothalamic obesity, 2022 https://pubmed.ncbi.nlm.nih.gov/35294397/ [^10]: Tesofensine, appetite and brain dopamine in obese rats, 2013 https://pubmed.ncbi.nlm.nih.gov/23932919/ [^11]: Tesofensine, food intake and dopamine receptors in obese rats, 2012 https://pubmed.ncbi.nlm.nih.gov/21889317/ [^12]: Review: tesofensine as a drug for obesity, 2009 https://pubmed.ncbi.nlm.nih.gov/19777399/ [^13]: ClinicalTrials.gov: tesofensine for weight loss in obesity, Denmark, started 2006 https://clinicaltrials.gov/study/NCT00394667 [^14]: ClinicalTrials.gov: long-term safety of tesofensine in obesity, Denmark, started 2007 https://clinicaltrials.gov/study/NCT00481104 [^15]: ClinicalTrials.gov: tesofensine with metoprolol in obesity after hypothalamic injury, Denmark, started 2019 https://clinicaltrials.gov/study/NCT03845075 [^16]: 6abc News: a Danish trial of tesofensine for obesity, 2008 https://6abc.com/archive/6466750 [^17]: How the body breaks down and clears tesofensine, in six volunteers, 2026 https://pubmed.ncbi.nlm.nih.gov/42320973/