Non-deceptive placebo pills reduce stress, anxiety, and depression—even remotely administered

A recent study provides evidence that non-deceptive placebos—placebos given with full disclosure—can effectively reduce stress, anxiety, and depression, even when administered remotely. The findings, published in Applied Psychology: Health and Well-Being, demonstrate the potential of this simple, low-cost intervention to address significant mental health challenges, particularly during periods of prolonged stress such as the COVID-19 pandemic.

The COVID-19 pandemic caused a sharp rise in global stress, anxiety, and depression. In the United States alone, the rate of severe psychological distress more than tripled during the pandemic, highlighting the urgent need for scalable and accessible mental health interventions. Prolonged stress, if unmanaged, can lead to significant emotional and physical health issues. However, many traditional mental health resources, such as therapy or medication, are costly, time-intensive, and not universally accessible.

“I am generally interested in testing and understanding low-effort interventions. In this study, I was interested in exploring non-deceptive placebos because they offer a unique, ethical, and low-effort approach to managing stress and improving mental health,” said study author Darwin A. Guevarra, an assistant professor of psychology at Miami University and the director of the
Affective Science and Psychophysiology Lab.

“During the COVID-19 pandemic, many people experienced prolonged stress, anxiety, and depression, and there was a clear need for scalable, accessible interventions. The pandemic offered a unique opportunity to test whether non-deceptive placebos could be administered remotely as a mental health support tool for people struggling during this global crisis.”

The researchers conducted a two-week randomized controlled trial with participants aged 18 to 30 who were experiencing moderate stress related to the pandemic. To ensure safety, participants with severe mental health conditions or those taking psychotropic medications were excluded. Recruitment was conducted online, targeting Michigan residents to account for regional variations in COVID-19 cases and restrictions.

Participants were randomly assigned to either a non-deceptive placebo group or a no-treatment control group. Those in the placebo group received placebo pills in the mail and participated in four virtual Zoom sessions. During these sessions, researchers explained the placebo effect, including how placebos can work even when individuals are aware they are taking inactive substances. Participants in this group were instructed to take one pill in the morning and another in the evening for the study’s duration. In contrast, the control group received no pills or additional intervention beyond completing periodic surveys.

The primary outcomes measured were levels of COVID-related stress, general stress, anxiety, and depression, assessed through validated self-report surveys at baseline, one week, and two weeks. Secondary outcomes included participants’ adherence to taking the placebo pills and their perceptions of the intervention’s feasibility, acceptability, and appropriateness.

The researchers found that participants in the non-deceptive placebo group experienced reductions in stress, anxiety, and depression over the two weeks, while those in the control group showed little or no improvement. By the end of the study, the placebo group’s reported stress and emotional distress had dropped to levels comparable to those achieved by more intensive mental health interventions, such as online cognitive behavioral therapy.

“The key takeaway is that non-deceptive placebos—placebos that participants know contain no active ingredients—can still significantly reduce stress, anxiety, and depression, even when administered remotely,” Guevarra said. “This suggests that simple, low-cost interventions, grounded in honest communication can effectively support mental health during prolonged periods of stress.”

The findings also highlighted the practicality of the intervention. Adherence to the placebo regimen was high, with participants taking their pills as instructed 92.5% of the time. Additionally, participants found the intervention easy to use, non-burdensome, and appropriate for the context of managing pandemic-related stress. These qualities make non-deceptive placebos particularly appealing as a mental health resource for individuals with limited access to traditional care or those who may struggle to engage with more demanding interventions.

“I was pleasantly surprised by how well participants adhered to the placebo regimen and how positively they perceived the intervention’s feasibility and acceptability,” Guevarra told PsyPost. “Despite knowing they were taking inert pills, participants still experienced meaningful psychological benefits, highlighting the power of belief and expectation in emotional well-being.”

While the findings are promising, the study has some limitations to consider. First, the sample size was relatively small, and most participants were young, white, and female. This lack of diversity may limit the generalizability of the results to broader populations.

“Larger and more diverse studies are necessary to confirm and extend these findings,” Guevarra noted.

The ability to administer non-deceptive placebos remotely has far-reaching implications for mental health care. This approach offers a scalable, low-cost solution that could benefit individuals who lack access to traditional mental health services due to financial, geographic, or logistical barriers. Moreover, the minimal effort required to participate makes this intervention particularly suitable for people experiencing low motivation or impaired self-regulation due to prolonged stress.

“This research highlights the importance of exploring unconventional yet ethical methods to support mental health, especially when traditional interventions may not be accessible,” Guevarra explained. “Non-deceptive placebos challenge the notion that treatments must involve active ingredients to be effective and open the door to innovative approaches in psychological care.”

Future research should explore the mechanisms underlying the effectiveness of non-deceptive placebos. While the placebo effect has traditionally been linked to expectations of benefit, this study found no significant correlation between participants’ expectations and their outcomes. This suggests that other factors, such as prior conditioning or implicit beliefs, may play a role. Understanding these mechanisms could help optimize the design and delivery of non-deceptive placebo interventions.

“My long-term goal is to explore how non-deceptive placebos can be integrated into broader mental health care strategies, particularly as scalable, low-cost interventions for managing stress and emotional distress,” Guevarra said. “I aim to investigate their effectiveness across diverse populations and various types of prolonged stress and to understand the psychological mechanisms that make them effective.”

The study, “Remotely administered non-deceptive placebos reduce COVID-related stress, anxiety, and depression,” was authored by Darwin A. Guevarra, Christopher T. Webster, Jade N. Moros, Ethan Kross, and Jason S. Moser.