Zeebo Effect, LLC · Huntington, Vermont, USA
Zeebo® Placebo Pills in Published Clinical Research
Zeebo placebo pills and tablets have been reviewed by Institutional Review Boards (IRBs) and used as the investigational agent in published clinical research since 2014. Studies naming Zeebo have appeared in PAIN, Scientific Reports (Nature), American Family Physician, Frontiers in Pain Research, Obesity, and Applied Psychology: Health and Well-Being, among others.
All Zeebo research supply is produced at FDA-registered manufacturing sites in the USA following cGMP, with Certificate of Analysis and annual stability testing included.
Published in
The 8 published studies below name Zeebo in their methods sections — drawn from a broader portfolio of engagements with more than 30 institutional research customers across the USA, Europe, and beyond since 2014. This page also includes field studies, peer-reviewed commentary, and co-authored works that are part of the broader open-label placebo research landscape in which Zeebo plays a central role.
Open-Label Placebo RCTs — Zeebo Supplied
Effects of Open-Label Placebos on Test Performance and Psychological Well-Being in Healthy Medical Students
This single-blinded RCT (N = 80 healthy medical students) demonstrated that a 21-day course of Zeebo open-label placebo significantly reduced subjective stress, fatigue, and confusion compared to controls during examination periods. Test performance was not improved overall, though within the OLP group, performance correlated positively with medication beliefs — indicating an expectation-modulated response.
View Publication"OLP can counteract negative effects of acute stress on psychological well-being and might improve cognitive performance if supported by positive treatment expectations."
— Scientific Reports, Nature Publishing Group, 2021
Effects of Open-Label Placebo on Pain, Functional Disability, and Spine Mobility in Patients with Chronic Back Pain
This RCT (N = 127 patients, chronic back pain duration >12 weeks) found that a 3-week open-label placebo treatment produced significantly greater reductions in pain intensity and patient-reported functional disability than TAU alone. Depression scores also improved. Summarized in American Family Physician (2021) with explicit reference to Zeebo as a nonprescription option for clinicians.
View Publication"Our study demonstrates that a 3-week open-label placebo treatment is safe, well tolerated and reduces pain, disability, and depressive symptoms in chronic back pain."
— PAIN, International Association for the Study of Pain, 2019
Non-Deceptive Placebos Reduce COVID-Related Stress, Anxiety, and Depression
This RCT examined the effects of non-deceptive placebo on a population experiencing long-term stress during the COVID-19 pandemic. Compared to a no-treatment control group, the Zeebo OLP group showed significantly accelerated reductions in COVID-related stress, overall stress, anxiety, and depression over two weeks. The authors note the strong scalability potential of remotely administered OLP for populations without access to conventional mental health services.
View Publication"Remotely administered non-deceptive placebos have the potential to help individuals struggling with mental health concerns who would not have access to traditional mental health services."
— Applied Psychology: Health and Well-Being, IAAP, 2024
Open-Label Placebo Treatment Does Not Enhance Cognitive Abilities in Healthy Volunteers
This pre-registered RCT (N = 78 healthy volunteers) investigated whether a 21-day Zeebo OLP treatment could enhance multiple sub-domains of cognitive performance. The study found no improvements in objective cognitive outcomes — including attention, working memory, and instrumental learning — while confirming the replicability of the Zeebo OLP protocol. An important null-result contribution to the open-label placebo literature.
View Publication"OLPs may enhance many aspects of functioning, but may not always work in all populations or against all symptoms — highlighting the importance of continued rigorous investigation."
— Scientific Reports, Nature Publishing Group, 2023
Open-Label Placebo Treatment for Cancer-Related Fatigue: A Randomized-Controlled Clinical Trial
This IRB-approved RCT (N = 74 cancer survivors with moderate-to-severe fatigue) found that open-label placebo produced a 29% improvement in fatigue severity and a 39% improvement in fatigue-disrupted quality of life compared to treatment as usual, with medium-to-large effect sizes (d = 0.63 and d = 0.76 respectively). Among the first studies to establish OLP efficacy in an oncology population.
View Publication"Results demonstrate that even when administered openly, placebos improve cancer-related fatigue — and dopaminergic systems may be associated with this response."
— Scientific Reports, University of Alabama at Birmingham, 2018
Conventional Blinded RCT — Zeebo Supplied
A Randomized, Double-Blind, Placebo-Controlled Pilot Trial With Open-Label Extension of Sirona, a Hydrogel for Weight Loss
This double-blind, placebo-controlled pilot RCT (N = 40 adults, BMI 30–41) evaluated Sirona, a novel dual-polymer hydrogel pill for weight management. Zeebo supplied the matched placebo comparator. The study found the treatment was safe and well tolerated, with participants on Sirona showing greater weight loss compared to placebo. The trial was registered on ISRCTN (14083641) and the results published in the peer-reviewed journal Obesity.
View Publication (Open Access)"The placebo pills (Zeebo Effect LLC) consisted of microcrystalline cellulose (96%), and they were the same size, color and shape and similar weight."
— Obesity, Wiley / NIHR Southampton Biomedical Research Centre, 2024
Follow-Up & Longitudinal Studies
No Long-Term Effects After a 3-Week Open-Label Placebo Treatment for Chronic Low Back Pain: A 3-Year Follow-Up
This longitudinal follow-up found no significant differences in pain intensity, disability, or mood between the original OLP and TAU groups at the 3-year mark. The short-term benefits observed in the parent RCT were not sustained. The study contributes important long-term safety and durability data and informs optimal dosing duration for future OLP trials.
View Publication"Given OLP's tolerability and safety, findings indicate clinically relevant short-term benefits — and underscore the need for studies examining longer treatment durations."
— PAIN, University Hospital Essen, 2023
Registered Clinical Trials
Open Label Placebo to Reduce Prescription Opioid Use
This registered trial investigates whether open-label placebo can reduce prescription opioid consumption, reflecting growing interest in non-pharmacological approaches to opioid stewardship. The Zeebo protocol is employed as the OLP intervention.
View Registration"A growing body of evidence demonstrates that no deception is necessary for placebo treatment to alleviate symptoms — including in opioid use disorder."
— ClinicalTrials.gov, NCT05014230, United States
Foundational Field Research
Open-Label Placebo Treatment in Chronic Low Back Pain: A Randomized Controlled Trial
This landmark RCT (N = 83 completers) is among the most widely cited studies in the open-label placebo literature. OLP produced significantly greater pain reduction across all three numeric rating scales compared to TAU alone (composite: 1.5 vs. 0.2 on a 10-point scale), with large-effect improvements in functional disability. The study established OLP as a clinically meaningful intervention for chronic low back pain and is the direct predecessor of the Zeebo-supplied Essen studies.
View Publication (Open Access)"Our findings suggest that OLP pills presented in a positive context may be helpful in chronic low back pain."
— PAIN, Harvard Medical School / Beth Israel Deaconess Medical Center, 2016
Published Works by Zeebo Effect
Can the Open Label Placebo Rationale Be Optimized?
This peer-reviewed perspective examines how the rationale provided to patients during OLP administration affects treatment outcomes, with a focus on pain and chronic conditions. It proposes an optimized framework for OLP rationale delivery — including the role of mindfulness and expectation-setting in modulating response magnitude.
View Publication (Open Access)"Mindfulness-based approaches to OLP delivery may enhance treatment outcomes by increasing present-moment awareness of placebo-associated sensations and expectations."
— Frontiers in Pain Research, Zeebo Effect LLC / Brown University, 2021
Peer-Reviewed Commentary & Citations
Short-Term Low Back Pain Relief with Placebo
This POEM (Patient-Oriented Evidence that Matters) evidence review summarizes the Kleine-Borgmann 2019 RCT and assigns a Level of Evidence of 2b. The review concludes that patients with long-term low back pain who knowingly took placebo twice daily reported less pain and disability than those receiving treatment as usual, and specifically names Zeebo as a nonprescription option available to practitioners.
View Publication"A nonprescription placebo (Zeebo) is available, or pharmacists can prepare placebo capsules. (Level of Evidence = 2b)"
— American Family Physician, AAFP, 2021
Placebos in Clinical Care: A Suggestion Beyond the Evidence
This peer-reviewed commentary in a major Australian medical journal evaluates the evidence base for open-label placebos in clinical care, explicitly referencing Zeebo as a commercially available product. Published in PMC/PubMed Central, the citation contributes to Zeebo's indexed academic presence internationally.
View Publication (Open Access)"It is now possible to purchase Zeebo (Zeebo Effect) placebo pills branded as 'Zeebo Relief Pure Honest Placebo.'"
— Medical Journal of Australia, University of Sydney / NHMRC, 2021
Open-Label Placebo Treatment to Improve Relaxation Training Effects in Healthy Psychology Students
This RCT (N = 160 psychology students) investigated whether OLP could improve compliance and outcomes in progressive muscle relaxation training. The study references the Zeebo protocol as the established methodological benchmark for open-label placebo pill research, reinforcing Zeebo's position as the field's standard research supply.
View Publication"The 21-day OLP application (two capsules per day labeled 'Zeebo') improved well-being — establishing it as the reference protocol for open-label placebo pill research."
— Scientific Reports, University of Graz, Austria, 2021
Supply Zeebo for Your Research
Zeebo Research has supplied clinical trials since 2015. We provide custom and standard placebo capsules and tablets, a Certificate of Analysis, IRB Letter of Support, and ongoing stability test updates for multi-year studies.
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