What is tesofensine?
Tesofensine was developed by the Danish company NeuroSearch under the code NS2330. It was first studied as a possible treatment for Parkinson's disease and Alzheimer's disease. Those trials did not show enough benefit for the brain conditions, but participants tended to lose weight. That led researchers to test it as an obesity drug.
Tesofensine is a small molecule, not a peptide. It belongs to a group of drugs called reuptake inhibitors, which also includes many antidepressants. Later development has included a combination of tesofensine with metoprolol, a heart rate medicine, studied in rare forms of obesity such as hypothalamic obesity. As of 2026, tesofensine is still investigational in the US and Europe.
How does tesofensine work?
Nerve cells release chemical messengers called monoamines, then pull them back in through transporter proteins. Tesofensine blocks the transporters for serotonin, noradrenaline and dopamine, so more of each stays active between nerve cells. That is why it is called a triple reuptake inhibitor.
All three messengers help regulate appetite in the hypothalamus and the brain's reward system. Human studies suggest tesofensine works mainly by reducing hunger and increasing fullness. Researchers have also looked at energy use, but that effect appears smaller. The same chemicals affect heart rate, blood pressure, mood and sleep, which explains many of its side effects.
What has research looked at?
- Obesity
- In a phase 2 trial published in 2008, adults with obesity who also followed a diet lost more weight on average over 24 weeks with tesofensine than with placebo.
- Appetite
- Smaller human studies reported less hunger and more fullness in people taking tesofensine, which researchers think explains most of the weight effect.
- Parkinson's and Alzheimer's disease
- Earlier trials in these conditions did not show meaningful benefits for symptoms, which is why development moved to obesity.
- Rare obesity disorders
- The combination with metoprolol has been studied in small trials in hypothalamic obesity, which can follow damage to the hypothalamus.
- Mood and thinking
- Because it acts on serotonin, noradrenaline and dopamine, people sometimes suggest benefits for mood or thinking. These have not been established in trials.
Tesofensine has more human data than many compounds in this library, including a published placebo-controlled trial. But the trials were moderate in size and length, and long-term safety data in large groups of people are limited. Its effects on the heart and on mood over many years remain open questions.
Side effects and cautions
In the obesity trials, commonly reported side effects included dry mouth, nausea, constipation, diarrhea and trouble sleeping. Researchers also reported increases in heart rate and, in some participants, blood pressure. These effects fit with how the drug works, because noradrenaline and dopamine affect the heart and alertness. Anyone with health questions should talk to a qualified clinician.
- Heart and blood pressure
- A related older weight drug, sibutramine, which blocks serotonin and noradrenaline reuptake, was withdrawn in 2010 after a large trial linked it to more heart attacks and strokes in people with heart disease or high heart risk. Long-term heart safety of tesofensine has not been shown.
- Mood and sleep
- Drugs that change serotonin, noradrenaline and dopamine can affect mood, anxiety and sleep. People with psychiatric conditions were generally not the focus of the trials.
- Drug interactions
- It could interact with other medicines that act on these messengers, such as many antidepressants, stimulants and some migraine drugs.
- Misuse
- Drugs that raise dopamine can carry a risk of misuse. This has not been fully studied for tesofensine.
- Pregnancy and long-term use
- There are no safety data in pregnancy, and long-term effects are not well established.
Further reading
This page summarizes the research in plain words. To read the studies yourself:
- Published studies on Tesofensine PubMed, US National Library of Medicine
- Registered human trials of Tesofensine ClinicalTrials.gov
