What Happened When Colon Hydrotherapy Was Put to the Test?

Written by

Emma Child

Manager, Trainer and Therapist

A 2026 randomised controlled trial investigated practitioner-operated colon hydrotherapy in adults whose standard colonoscopy preparation had not worked adequately. One rescue treatment produced measurable results—and raised important questions for future research.

Why this colon hydrotherapy trial matters

Modern clinical research specifically investigating professional colon hydrotherapy remains limited. That makes the 2026 study by Zhang and colleagues, published in the European Journal of Medical Research, particularly noteworthy.

It was a prospective randomised controlled trial—a design in which participants are randomly allocated to different interventions so outcomes can be compared more reliably. The clinicians who examined the bowel during colonoscopy did not know which rescue treatment each participant had received, helping to reduce assessment bias.

Most importantly, the outcome was not simply whether participants felt more emptied. Researchers performed colonoscopy afterwards and used a validated medical scale to score how clean each section of the colon actually was.

What exactly did the researchers test?

The trial recruited 120 adults at a single hospital in Beijing, China. Each participant had completed routine PEG preparation for colonoscopy, but their bowel was still judged inadequately cleansed.

PEG, or polyethylene glycol, is a laxative solution commonly taken before colonoscopy. It helps flush stool from the bowel, but the initial preparation is not adequate for every patient. When this happens, clinicians need a rescue strategy so the colonoscopy can proceed safely and provide a useful view.

Participants were randomly assigned to one of two same-day rescue treatments:

• Hydrotherapy: a device-assisted irrigation treatment delivered and monitored by trained endoscopy nurses; or
• Additional PEG: a further two litres of oral PEG solution.

One practitioner-operated treatment, followed by colonoscopy

Participants in the hydrotherapy group received one treatment only. This was not a series of colonics over several days or weeks.

The study used a DJS-C hydrotherapy device. Certified endoscopy nurses completed structured training and competency assessment before delivering the intervention. Water temperature was maintained at 36–37°C, flow at approximately 0.7–0.8 litres per minute and pressure below 10 kPa, according to a defined protocol.

This was not a self-administered irrigation treatment. Practitioners actively delivered and monitored it, including the device settings and the patient’s response. That feature makes the research more relevant to professionally delivered colon hydrotherapy than studies of small home-irrigation systems.

There are meaningful similarities to the practitioner-operated Rojas Colon Hydrotherapy approach used at Bottoms Up Colonics, where trained practitioners manage the treatment and respond to the client throughout the session. However, the equipment, clinical protocol, patient population, indication and hospital setting were different. The trial did not test the Rojas system or routine colon hydrotherapy in generally healthy clients.

Researchers looked inside the colon afterwards

Bowel cleanliness was evaluated during colonoscopy using the Boston Bowel Preparation Scale (BBPS). This validated scoring system rates the right, transverse and left sections of the colon from 0 to 3, producing an overall score from 0 to 9.

In this study, a total score of 6 or more was considered adequate and a score of 8 or 9 was considered excellent. Because the endoscopists assigning these scores were blinded to treatment allocation, they did not know whether a participant had received hydrotherapy or additional PEG.

What did the trial find?

Higher overall cleanliness scores

The hydrotherapy group achieved a median total BBPS score of 7.5 out of 9, compared with 6.5 out of 9 in the additional-PEG group. The difference was statistically significant. The clearest segment-level improvement occurred in the left colon.

This is an objective finding: the colon was examined directly after treatment and scored by clinicians who were unaware of the treatment allocation.

Half achieved excellent cleansing

Perhaps the most striking finding was the proportion achieving excellent bowel preparation. After one hydrotherapy treatment, 50.0% of participants scored 8 or 9, compared with 17.2% after an additional two litres of PEG.

That represents a difference of 32.8 percentage points in this study population. It suggests hydrotherapy may be particularly useful when the clinical objective is to move beyond merely adequate cleansing to an excellent view.

But the overall pass rate was not better

This result is just as important. When researchers looked at the proportion reaching the minimum threshold for adequate preparation, the hydrotherapy group recorded 80.4% and the additional-PEG group 89.7%. That difference was not statistically significant.

Less time was required

Median preparation time was 50 minutes for hydrotherapy and 100 minutes for additional PEG. The authors estimated a 40-minute median difference between groups. For a same-day rescue procedure, time may matter to both the patient and the endoscopy service.

What happened with comfort and safety?

Gastrointestinal adverse reactions were reported by 30.4% of participants receiving hydrotherapy and 82.8% receiving additional PEG. Nausea and vomiting were common in the PEG group and were not reported in the hydrotherapy group. Abdominal distension and abdominal pain were also less frequent with hydrotherapy.

Local anal itching or discomfort occurred more often after hydrotherapy—16.1% compared with 5.2% after PEG—although this difference did not reach statistical significance. Electrolyte disturbances were similar between groups, and the researchers reported no severe neurotoxic effects or clinically significant between-group electrolyte differences.

Participants also reported greater satisfaction with hydrotherapy, and 71.4% said they would be willing to use the method again compared with 31.0% in the additional-PEG group.

The result depended on how poor the initial preparation was

In a subgroup with “slightly poor” initial preparation, hydrotherapy produced a higher median overall BBPS score than additional PEG. In participants whose initial preparation was classified as “very poor”, however, the overall scores were the same—6 versus 6.

This matters clinically. Hydrotherapy may not overcome every type or severity of inadequate preparation, and cleansing of the right colon remained a limitation. Future research needs to identify which patients are most likely to benefit.

What this study does—and does not—prove

What it supports

• One practitioner-operated hydrotherapy intervention can be studied objectively in a controlled clinical setting.
• In adults with inadequate cleansing after standard PEG, hydrotherapy produced a higher median BBPS score and more excellent preparations than drinking an additional two litres of PEG.
• The intervention was faster, caused fewer gastrointestinal reactions and was preferred by more participants in this trial.

What it cannot establish

• It does not show that colon hydrotherapy should replace standard first-line colonoscopy preparation.
• It does not establish benefits for constipation, bloating, general wellbeing or other wellness outcomes.
• It does not test repeated colon hydrotherapy treatments.
• It does not show improved polyp detection, adenoma detection, cancer outcomes or long-term health outcomes.
• It does not prove that every colon hydrotherapy device, protocol or practitioner model will produce the same results.

The median difference was one BBPS point. While statistically significant, the minimum change that patients or clinicians would consider meaningfully better has not been firmly defined for this situation. The paper therefore provides promising early evidence—not a final clinical verdict.

Important limitations for medical professionals

The trial was conducted at one hospital in China in a selected group of patients, limiting how confidently its results can be generalised to other health systems and populations. Participants and treatment staff could not be blinded, which may have influenced comfort and satisfaction reporting.

The study used bowel cleanliness as a surrogate outcome and was not designed to measure lesion detection, cancer prevention, rare complications, cost-effectiveness or long-term outcomes. Some assessments, including the pre-randomisation grading of inadequate preparation and satisfaction measures, had methodological limitations identified by the authors.

The research was funded by the Beijing Changping Hospital of Traditional Chinese Medicine Discipline Development Project Fund. The authors reported that the funder had no role in the study design, data collection, analysis, interpretation or manuscript preparation.

Why this matters for professional colon hydrotherapy

This trial helps move the discussion beyond assumptions. It demonstrates that a practitioner-operated water-based intervention can be placed inside a randomised study, standardised, compared with an active treatment and evaluated through blinded colonoscopy.

For practitioners, that is encouraging—but it also shows what responsible evidence communication looks like. The strongest claim is narrow: in this particular rescue setting, hydrotherapy improved several bowel-cleansing outcomes compared with additional PEG, while the adequate-preparation rate was not superior.

For a broader overview of the evidence, read our scientific review of colon hydrotherapy. If you are new to the treatment, see what colon hydrotherapy is and how the practitioner-supported process works.

What should future research investigate?

This study provides a useful foundation for larger, multicentre trials. Future research could examine:

• whether results can be replicated across hospitals, countries and practitioner models;
• which patients and patterns of inadequate preparation respond best;
• whether right-colon cleansing can be improved;
• effects on adenoma and lesion detection, rather than cleanliness scores alone;
• rare adverse events and longer-term safety;
• cost-effectiveness and effects on endoscopy scheduling; and
• whether comparable results occur with other professional hydrotherapy systems and protocols.

The bottom line

A 2026 randomised controlled trial put practitioner-operated hydrotherapy to a meaningful clinical test. Among adults whose standard PEG preparation had been inadequate, one hydrotherapy treatment produced a higher median bowel-cleanliness score, more excellent preparations, shorter preparation time and fewer gastrointestinal adverse reactions than an additional two litres of PEG.

At the same time, hydrotherapy did not produce a statistically higher overall adequate-preparation rate, and the trial cannot be generalised to routine wellness treatment or every form of colon hydrotherapy.

That is what good science often looks like: a result that is genuinely interesting, clinically relevant and worthy of further study—without asking it to prove more than it actually tested.

Frequently asked questions

Reference

Zhang D, et al. Efficacy and safety of remedial hydrotherapy enema for inadequate bowel preparation in colonoscopy: a prospective randomised controlled trial. European Journal of Medical Research. 2026;31:1059. doi:10.1186/s40001-026-04633-0.