Plenty of numbers about hypnosis circulate without a source, a sample or a comparison group. A “90% success rate” says very little if it is unclear who was measured, on what, and compared with what.
This page collects 17 findings from published research: randomized trials, meta-analyses, norming studies and surveys. Each figure comes with its sample, its limitation and a link to the original publication.
The research figures describe study results, not treatment results at Mion Hypnose. Findings from my own practice are kept separate in the section Findings from the Mion Hypnose practice. For more background, see the page on the science of hypnosis. Last updated: .
Key takeaways
- 19.2% of 99 German adolescents were classified as highly hypnotizable. High hypnotizability applies to a minority, and its size depends on the cutoff chosen. (Peter et al., 2015)
- Hypnotizability correlated at r = .71 across 25 years. Hypnotizability behaves more like a stable trait than like a passing state. (Piccione, Hilgard & Zimbardo, 1989)
- 40.8% reported adequate IBS relief after 3 months of individual hypnosis, compared with 16.7% in the control group. The share was more than twice that of the control group, yet most participants did not meet the criterion. (Flik et al., 2019)
- 15.0% were continuously smoke-free 12 months after hypnosis, and 15.6% after cognitive behavioral therapy. No statistically significant difference from an established method, and in both groups the large majority did not stay continuously smoke-free. (Batra et al., 2024)
- 78.8% achieved IBS symptom improvement after 6 sessions of gut-focused hypnosis, and 73.9% after 12 sessions. Six sessions were noninferior to twelve in this trial. (Hasan et al., 2021)
- 54.9% of respondents with no hypnosis experience would consider hypnosis treatment. Openness is far greater than the actual use of 7.6% in the same survey. (Palsson, Twist & Walker, 2019)
- A 2024 umbrella review covered 49 meta-analyses with 261 distinct primary studies. There is a lot of research, but only 9 of the 49 meta-analyses received a high quality rating. (Rosendahl, Alldredge & Haddenhorst, 2024)
Hypnotizability statistics
People do not all respond to hypnotic suggestions to the same degree. This section shows how hypnotizability is measured, how stable it stays over time and how little of it can be predicted from personality.
19.2% of 99 German adolescents were classified as highly hypnotizable. 19 of the 15- to 19-year-olds scored 9–12 on the Harvard scale; with a stricter cutoff of 10 the proportion was 8.1%. The share therefore depends on the cutoff and is not a worldwide population estimate. (Peter et al., 2015)
Hypnotizability correlated at r = .71 across 25 years. Measured in 50 people who were followed up. The value describes the relationship between two measurements, not a success rate. (Piccione, Hilgard & Zimbardo, 1989)
Personality and gender explained approximately 6% of the variation in hypnotizability. The model, using the five broad personality dimensions and gender, was tested in 285 undergraduates (variance after adjustment). A personality profile therefore says little about hypnotizability. (Green, 2004)
Treatment outcome statistics
Treatment outcomes only make sense next to their comparison group. The figures below come from randomized trials and meta-analyses, and include both advantages and results where hypnosis did not come out ahead.
Irritable bowel syndrome
40.8% reported adequate IBS relief after 3 months of individual hypnosis, compared with 16.7% in the control group. The control group received educational supportive therapy; the IMAGINE trial analysed 342 participants by intention to treat. Relief does not mean cure. (Flik et al., 2019)
At 12 months, 49.5% of group-hypnosis participants reported adequate IBS relief, compared with 22.6% in the control group. The figures come from the same IMAGINE trial. They do not establish that group hypnosis is superior to individual hypnosis. (Flik et al., 2019)
Hot flashes, smoking cessation and urgency incontinence
The hot-flash score fell by 53.4% after 6 weeks of hypnosis audio, and by 40.9% with the sham intervention. 250 women were randomized. The score combines frequency and severity, and the sham intervention was also followed by a marked reduction. This is not a cure rate. (Hot-flash RCT, 2025)
15.0% were continuously smoke-free 12 months after hypnosis, and 15.6% after cognitive behavioral therapy. 360 people were randomized and received six group sessions each. The outcome was CO-validated; the difference was not statistically significant. (Batra et al., 2024)
Urgency-incontinence episodes fell by a median of 73.0% after 2 months of hypnosis, and by 88.6% with medication. 152 women were randomized. Hypnosis did not meet the prespecified noninferiority criterion at the primary endpoint. (Komesu et al., 2020)
Medical procedures
During medical procedures, pain was on average 1.14 cm lower on the visual analogue scale with hypnosis. Meta-analysis of 6 randomized trials with 811 participants; 95% confidence interval −1.86 to −0.41 cm. The studies differed substantially (I² = 91%), so the average should be read with caution. (Lahoud, Tell Gurary & Elia, 2025)
The relative risk of nausea or vomiting after procedures was 0.43 with hypnosis. 3 randomized trials, 185 participants; 95% confidence interval 0.25–0.74. That is a 57% lower relative risk, not 57 percentage points fewer people affected. (Lahoud, Tell Gurary & Elia, 2025)
Duration and delivery statistics
How many sessions does it take, and in what settings is hypnosis used? Two studies offer reference points, both with clearly limited reach.
78.8% achieved IBS symptom improvement after 6 sessions of gut-focused hypnosis, and 73.9% after 12 sessions. 178 of 226 and 164 of 222 participants respectively improved by at least 50 IBS-SSS points. Six sessions met the noninferiority criterion; each group was assessed at its treatment completion. (Hasan et al., 2021)
40 of 40 patients with claustrophobia completed their MRI scan under hypnosis. Selected patients in a retrospective Swiss study; all 40 in the anesthesia comparison group also completed scanning. A small, nonrandomized study and not a general success guarantee. (Rizzo et al., 2021)
Use and attitude statistics
Surveys show how widespread hypnosis is and what people think of it. They measure self-reports and opinions, not treatment effects.
7.6% of surveyed US adults had previously undergone hypnosis treatment. Self-report in a demographically balanced online survey of 1,000 adults, 2019. This is not a Swiss usage estimate. (Palsson, Twist & Walker, 2019)
54.9% of respondents with no hypnosis experience would consider hypnosis treatment. Among respondents who had never undergone hypnosis treatment in the same US survey. Willingness is not actual use. (Palsson, Twist & Walker, 2019)
88% of surveyed clinicians rated therapeutic rapport as very or extremely important. Survey of 691 clinicians across 31 countries, 2023. A professional opinion, not a measured treatment effect. (Palsson et al., 2023)
Hypnosis research statistics
How much research exists, and how consistent are its findings? Reviews count studies and rate their quality, which is not the same as a success rate among patients.
A 2024 umbrella review covered 49 meta-analyses with 261 distinct primary studies. Nine of the 49 meta-analyses received a high methodological quality rating using AMSTAR 2. The count describes this one review, not all hypnosis research. (Rosendahl, Alldredge & Haddenhorst, 2024)
47.7% of 44 sleep studies reported positive findings. A 2023 review: 47.7% positive, 22.7% mixed, 29.5% no impact. These are percentages of studies, not patients, and not a success rate weighted by study size. (Wofford et al., 2023)
Findings from the Mion Hypnose practice
The figures in this section do not come from published studies but from my own practice records as a hypnotherapist. They describe the clients I see, not hypnosis in general.
87% of clients who attended at least three sessions reported a noticeable improvement in their concern afterwards. Clients who stopped after one or two sessions are not included, because their outcome is hard to establish: some stop because it has already helped, others for different reasons. From some I only hear years later, through someone else, that it worked well. I counted what clients told me themselves, ranging from “it’s much better” to “the issue I came for is completely gone”. There is no standardized questionnaire and no comparison group.
68% of clients had an inaccurate idea of what hypnosis is at their first session. Most pictured hypnosis as it appears in films or stage shows: losing consciousness, responding to a finger snap or following a pendulum. In therapeutic hypnosis you stay awake and responsive.
60% of clients prefer in-person sessions to online sessions. Of these, 19% switch to online after their first in-person session because it fits their day more easily. For them, the point is to meet once in person. Once trust is there, they choose online.
Analysis: Jan Mion, Hypnotherapist EZC, Mion Hypnose. Based on my own session notes, in which I wrote down what clients told me. No standardized outcome measure, no comparison group, no independent review. Read these figures as a description of my practice, not as a forecast for an individual treatment. They are not a guarantee or a promise of a cure, and hypnosis does not replace medical assessment or treatment.
What these hypnosis statistics mean in practice
Study figures cannot tell you how an individual treatment will go. They do help to set expectations and to ask better questions.
Read results as a range, not a promise
In the studies cited here, some participants reached the target and others did not, depending on the condition and the outcome measured. A rate from one study is not a forecast for one person, and it is not a statement about results at Mion Hypnose. The hypnotherapy overview lists the topics hypnosis is used for in practice.
Look at the comparison group
A 53.4% reduction reads differently once the sham intervention reaches 40.9%. What carries the information is the gap to the control, together with sample size and study design.
Do not equate hypnotizability with success
The hypnotizability figures come from standardized scales. They describe how people respond to test suggestions, not how well a treatment works. The page on the hypnosis method explains how sessions are structured.
Have medical complaints assessed by a doctor
Many of these studies concern medical diagnoses such as irritable bowel syndrome or urgency incontinence. Hypnosis does not replace medical assessment or treatment. To see what a session involves, read My first hypnosis session; for questions, get in touch.
Methodology and sources
A curated collection of published findings, not an exhaustive systematic review. Literature checked on 19 September 2026. Figures refer to the stated samples and outcomes, not to results at Mion Hypnose. Percentages, correlations and effect sizes measure different things and cannot be ranked against each other. Studies and reviews may overlap. Citation years refer to the original publication.
Sources
Peter et al.: Harvard scale adolescent norms (2015) · Piccione, Hilgard & Zimbardo: 25-year stability (1989) · Green: personality and hypnotizability (2004) · Flik et al.: IMAGINE IBS trial (2019) · Hot-flash RCT: hypnosis audio vs sham (2025) · Batra et al.: smoking cessation, hypnosis vs CBT (2024) · Lahoud, Tell Gurary & Elia: hypnosis for procedures, meta-analyses (2025) · Komesu et al.: urgency incontinence, hypnosis vs medication (2020) · Hasan et al.: 6 vs 12 sessions for IBS (2021) · Rizzo et al.: hypnosis for MRI and claustrophobia (2021) · Palsson, Twist & Walker: US population survey (2019) · Palsson et al.: international clinician survey (2023) · Rosendahl, Alldredge & Haddenhorst: umbrella review of meta-analyses (2024) · Wofford et al.: review of hypnosis and sleep (2023)