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International meta-analysis by the Medical Center - University of Freiburg points to benefits of open-label placebos / Publication in Scientific Reports

Medication without an active ingredient can also alleviate symptoms - even if patients know that it is a placebo. This is shown by an international meta-analysis led by the Medical Center - University of Freiburg, which was published in the journal Scientific Reports on August 15, 2025. It analyzed 60 clinical and experimental studies with a total of 4648 participants. The result: so-called open placebos, which are clearly described as being free of active ingredients, can noticeably improve pain, fatigue or depressive symptoms. The positive effect tended to be greater if the patients had previously been comprehensively informed about the possible effects of placebos.

"Our analysis uses a large number of different studies to show that the administration of open placebos can be an effective intervention in various areas. Obviously, the process of administering and taking a drug is itself an effective medical ritual," says study leader Prof. Dr. Stefan Schmidt, research professor in the Department of Psychosomatic Medicine and Psychotherapy at the Medical Center - University of Freiburg.

Effect without active ingredient

In contrast to conventional placebos, where patients do not know that they are receiving a placebo, open placebos are deliberately declared as such. The analysis now shows that simply administering a drug with the transparent information that it is a placebo can be enough to alleviate symptoms. The effect was particularly clear for symptoms that are subjectively assessed - such as pain or exhaustion. However, it is likely that not only the intake but also the corresponding information plays an important role. Studies in which the mode of action of placebos was explained in detail and clearly tended to produce stronger effects than those without information.

No significant effect on objective health values

In the studies evaluated, no significant effect has been shown to date for objectively measurable parameters such as blood values, sleep data or lung function. It remains to be seen whether prolonged use also leads to changes in biological parameters. However, the effect was independent of the dosage form: both tablets and drops or sprays achieved comparable results.

"Our results encourage us to continue researching open placebos - in particular their long-term effect and the question of whether they also have an impact on objective health parameters," says Schmidt. "In the future, this could lead to a new, ethically responsible treatment approach, as we can now administer effective placebos without deception."

Original title of the study: Effects of open-label placebos across outcomes and populations: An updated systematic review and meta-analysis of randomized controlled trials

DOI:https://doi.org/10.1038/s41598-025-14895-z

Link to the study: https: //www.nature.com/articles/s41598-025-14895-z