Hypnosis has a real evidence base, and a real problem with memory

Many people first meet hypnosis on a stage, where volunteers seem to obey every command. That picture is sticky. In a 1995 study of 205 college students, watching a stage show made audience members more likely to believe that a hypnotized person behaves like a robot and acts on every suggestion. A lecture about hypnosis made them less likely to believe it.

The clinical version looks nothing like the show. In a 2007 trial at Mount Sinai School of Medicine in New York, 200 women scheduled for breast biopsy or lumpectomy were randomly assigned to one of two 15-minute sessions before surgery. One group got hypnosis with a psychologist; the other spent the same time with an empathic listener. The hypnosis group needed less of the sedative propofol and the local anesthetic lidocaine, reported much less pain and nausea at discharge, and cost the hospital about $773 less per patient, mainly because surgery took less time. Patients knew which group they were in, a limit the researchers stated plainly.

Those two scenes frame the real story. Hypnosis has a genuine evidence base for a narrow set of uses, chiefly medical procedures and irritable bowel syndrome that hasn’t responded to other care. It also has a documented harm record, and the clearest part of that record concerns memory, not mind control. And the title on a hypnotist’s door says little about training, because no US state licenses hypnotherapy as a profession of its own.

The harm record: memory first, then the stage

Hypnotically refreshed memory

In 1985 the American Medical Association’s Council on Scientific Affairs reviewed the use of hypnosis to refresh recollection. Its report in JAMA concluded that memories obtained under hypnosis can involve confabulation, meaning gaps filled with invented detail, and pseudomemories. Such recall, the council found, is not more accurate and appears less reliable than ordinary recall. It warned that hypnotizing witnesses and victims could have serious consequences for the legal process.

Two years later the US Supreme Court relied on that report in Rock v. Arkansas, decided 5 to 4 on June 22, 1987. Justice Blackmun’s majority opinion described three risks. Hypnotized subjects become more suggestible. They tend to confabulate. And they can experience memory hardening, a growing confidence in both true and false memories that blunts cross-examination. The opinion added that the most common response to hypnosis appears to be an increase in both correct and incorrect recollections.

The holding is narrow and often misdescribed. The Court did not endorse hypnotically refreshed testimony. It ruled that Arkansas’s blanket rule barring all of a criminal defendant’s own testimony after hypnosis violated that defendant’s right to testify on his or her own behalf. Rules for other witnesses stayed with the states, which in 1987 ranged from outright exclusion to case-by-case safeguards. This article does not describe how each state handles the question today.

The concern hasn’t faded. A 2025 review in Frontiers in Psychology concluded that hypnotic regression, meaning hypnosis used to revisit earlier life events, and guided imagery should both be used with caution, because they can produce recall of events that never happened. Why imagery and hypnosis are so hard to pull apart in research is explained in the guided imagery article.

Recovering memories is the use where the evidence most clearly points toward harm.

Stage shows and dissociation

The stage-hypnosis record consists of small studies and case reports. It shows that harms happen. It cannot say how often.

A 1992 study in the Journal of Abnormal Psychology followed up 22 people who had volunteered at university stage shows. Most described the experience positively. Five reported partial or complete amnesia afterward, and one could not break through it at all and felt annoyed and frightened. Five believed the hypnotist had controlled their behavior. Those tested later scored mostly moderate to high on a standard hypnotizability scale.

Case reports describe more serious events. A 1995 letter in the British Journal of Psychiatry reported a schizophreniform psychosis, a short-lived psychotic illness, after stage hypnosis. A 2010 case report by clinicians at Walter Reed described a soldier, wounded in combat a year earlier, who volunteered at a show and then had a dissociative episode lasting more than three hours. He assaulted an acquaintance, believed he was a prisoner of war and was hospitalized with a diagnosis of acute psychotic reaction.

In Britain, public stage hypnotism has needed local authorization since the Hypnotism Act 1952. One council’s published conditions require volunteers to be 18 or older and require the performer to warn the audience about possible embarrassment or anxiety. They also ban suggestions of age regression, suggestions that a subject has lost a body part, catalepsy stunts, consumption of anything harmful and demonstrations of pain blocking.

Who is most vulnerable? In an April 2024 article in APA’s Monitor on Psychology, the researcher Devin Terhune described high hypnotizability as cutting both ways. He pointed to research linking it with higher rates of dissociative problems, including functional neurological disorders and post-traumatic stress disorder.

Clinical settings look calmer on paper. A 2016 review of meta-analyses in Deutsches Ärzteblatt International found two that compared side effects and safety, and neither showed a difference between hypnosis and control treatments. The 2019 Cochrane review on smoking found very little evidence on harms and none suggesting hypnotherapy causes them, mostly because trials didn’t say whether they collected adverse events. The National Center for Complementary and Integrative Health (NCCIH) hypnosis page, marked as last updated in January 2020 even though it cites a 2021 guideline, has no safety section at all. A missing federal warning is not evidence of safety.

What clinicians mean by hypnosis

The American Psychological Association’s Society of Psychological Hypnosis, its Division 30, published a revised definition in 2015. As the APA’s Monitor on Psychology reported in 2024, the division describes hypnosis as “a state of consciousness involving focused attention and reduced peripheral awareness,” marked by an increased capacity to respond to suggestion.

In clinical use, a session usually has two stages: an induction, the process of entering that focused state, followed by suggestions aimed at a specific problem. Gary Elkins, a Baylor University psychologist and lead author of the definition paper, told the Monitor that hypnosis is not a primary intervention, describing it instead as an adjunct to psychotherapy. That framing matches the guidelines below, which treat hypnosis as an add-on for defined problems, delivered within clinical care.

People differ widely in how they respond. According to the Monitor, hypnotizability follows a bell curve: roughly 10 to 20 percent of people are not very hypnotizable, about the same share are highly responsive, and everyone else falls in between. The highly responsive group is also the one the dissociation research above singles out.

Irritable bowel syndrome, read precisely

Gut-directed hypnotherapy uses suggestions focused on bowel function and pain. It has the strongest record of any use of hypnosis, and it is still regularly overstated.

The UK guideline. NICE, England’s guideline body, names hypnotherapy in its irritable bowel syndrome guideline, CG61, in text dated 2008. The recommendation covers only refractory IBS: people whose symptoms have not responded to drug treatment after 12 months and who still have a continuing symptom profile. For them, NICE says referral for cognitive behavioral therapy, hypnotherapy or other psychological therapy should be considered. In April 2025 NICE reviewed the guideline’s clinical-management section, which holds that recommendation, and decided not to update the guideline. That is a conditional referral for a defined subgroup, not a first-line recommendation for everyone with IBS.

The US guideline. The American College of Gastroenterology’s first IBS guideline, published in January 2021, suggests gut-directed psychotherapy for overall IBS symptoms. NCCIH reports that the recommendation includes gut-directed hypnotherapy and is conditional, based on very low-quality evidence.

The trials. A 2020 network meta-analysis in Gut, pooling 41 trials with 4,072 adults, found gut-directed hypnotherapy, face-to-face cognitive behavioral therapy (CBT) and self-guided CBT broadly similar, with none superior to another. Hypnotherapy cut the relative risk of still having symptoms after treatment by about a third. The authors warned that the trials carried a high risk of bias, with funnel-plot asymmetry, a statistical sign that small negative studies may be missing, so the benefit of all the psychological therapies was probably overestimated.

The largest single trial, IMAGINE, published in The Lancet Gastroenterology & Hepatology, randomized 354 patients at 11 Dutch hospitals to six sessions of individual or group hypnotherapy or to an educational supportive program. At three months, 40.8 percent of the individual-therapy group reported adequate relief, against 33.2 percent with group therapy and 16.7 percent of controls. At 12 months the figures were 40.8, 49.5 and 22.6 percent. Group sessions worked about as well as individual ones. Read the other way, most patients did not report adequate relief.

Children’s abdominal pain points the same direction. A 2017 Cochrane review of psychological treatments for recurrent abdominal pain in children found that hypnotherapy, a category that included imagery studies, improved treatment success across four small trials with 146 children, on low-quality evidence. The one trial with long follow-up reported success in 68 percent of hypnotherapy patients after five years, against 20 percent with usual care.

On this library’s evidence scale, gut-directed hypnotherapy is recommended by name in a clinical guideline for refractory IBS, and its wider trial record is positive but inflated by bias.

Procedures, surgery and pain

The guideline standing here is the clearest anywhere for hypnosis. The 2022 guideline on integrative pain care in oncology was produced by the American Society of Clinical Oncology together with the Society for Integrative Oncology, a pairing usually shortened to SIO-ASCO. It says hypnosis may be recommended to people with procedural pain, on intermediate-level evidence with moderate strength. The 2023 SIO-ASCO guideline on anxiety and depression, according to ASCO’s own summary table, says hypnosis may be offered for anxiety during diagnostic and treatment procedures, again on intermediate evidence with moderate strength. The journal abstract of the 2023 guideline leaves hypnosis out of its summary list, so the table is the place to check.

The trial base behind those positions is real and imperfect. A 2013 meta-analysis in Clinical Psychology Review pooled 34 trials with 2,597 adults undergoing surgery or medical procedures. Hypnosis improved emotional distress, pain, medication use, recovery and procedure time, with effect sizes running from moderate down to small. The authors judged the internal validity of the trials limited. The 2016 German review of meta-analyses, drawing on the same 34 trials, labeled the effect on procedural pain low, a reminder that one data set can be described generously or conservatively.

On the library’s scale, hypnosis for procedural pain and procedural anxiety in cancer care earns the highest grade available: a named recommendation in a clinical guideline, at moderate strength. No other use of hypnosis stands higher.

Other results, by population:

• Children’s needle procedures: a 2018 Cochrane review found that hypnosis reduced self-reported pain and distress across five trials with 176 children, on very low-quality evidence.
• Labor: a 2016 Cochrane review of nine trials with 2,954 women found hypnosis may reduce overall use of pain medication, on very low-quality evidence, but not epidural use, with no clear differences in satisfaction or sense of coping. Against relaxation-training controls, there were no clear differences at all, a comparison the library’s relaxation-practices piece picks up.
• Chronic musculoskeletal and nerve pain: a 2022 meta-analysis of nine trials with 530 people found a moderate reduction in pain intensity, and only programs of eight or more sessions showed a significant effect.
• Insomnia: the American Academy of Sleep Medicine’s 2021 guideline on behavioral and psychological treatments for chronic insomnia does not mention hypnosis at all, so that guideline offers it no support.

Smoking and hot flashes, where sources disagree

Smoking. Cochrane’s 2019 review covered 14 studies with 1,926 participants and judged only one at low risk of bias. Against behavioral treatment matched for contact time, the difference in quit rates was not statistically significant, on low-certainty evidence. Cochrane’s reviewers found the evidence insufficient to say whether hypnotherapy beats other support or quitting unaided. The Cochrane review concluded: “If a benefit is present, current evidence suggests the benefit is small at most.” The 2024 APA Monitor article listed quitting smoking among uses of hypnosis without that caveat. Cochrane’s conclusion is the one the evidence supports, and the claim sits at insufficient evidence to assess.

Hot flashes. A 2013 randomized trial in the journal Menopause enrolled 187 postmenopausal women having at least seven hot flashes a day. After five weekly sessions of clinical hypnosis, self-reported hot flashes fell 74 percent by week 12, against 17 percent with a structured-attention control. Hot flashes measured by skin-conductance monitors fell 57 percent, against 10 percent.

Here the professional and federal positions don’t match. The North American Menopause Society now calls itself the Menopause Society. Its 2023 nonhormone therapy position statement lists clinical hypnosis as recommended at its top evidence level, defined as good and consistent scientific evidence. NCCIH’s hypnosis page, dated January 2020, cites the society’s 2015 statement instead, which recommended hypnosis for hot flashes while acknowledging that the favorable evidence was limited. The federal page reflects a professional position the society has since strengthened, and the two stand side by side, unreconciled.

Registration without a training standard

Apply this library’s four-bucket test for credentials, which runs from defined in regulation through government certification and private certification to undefined, and hypnosis produces an odd result. The first bucket exists, and it is nearly empty.

Defined in regulation, in form only. Washington’s counselor law defines a hypnotherapist as a person registered under that chapter who practices hypnosis as a modality. The state’s application rule for hypnotherapists, WAC 246-810-090, effective July 1, 2025, asks for the application form, the fee and any supporting documents the health department requests. It sets no education or examination requirement. Connecticut requires anyone practicing hypnosis to register with its Department of Consumer Protection, for a nonrefundable $100 fee with annual renewal every October 31. Its page lists no education or training requirement, exempts people already licensed in medicine, nursing, counseling and other health fields, and requires registrants to report changes in name, address or sex-offender status within 30 days. In both states, registration tells the government who you are. It does not test what you know.

Government certification. None found.

Private certification. Two professional societies certify clinical hypnosis, and both build on an existing license. The American Society of Clinical Hypnosis requires at least a master’s degree in a health discipline, a state license to practice independently, approved workshop training, 20 hours of individual consultation and two years of practice using hypnosis. The Society for Clinical and Experimental Hypnosis requires a license for independent clinical practice, 70 hours of training that include ethics and research, two years of experience, and renewal every three years. According to the APA Monitor, Division 30 is working with that society on revised training standards.

Undefined. Elsewhere, titles such as hypnotherapist, certified hypnotist and consulting hypnotist carry no legal definition, and certificates from lay hypnosis organizations are private marks whose standards are set by the issuer.

One inference follows, and it is this article’s rather than any study’s. The trials behind the guideline recommendations ran in hospitals and clinical programs; the Mount Sinai sessions, for example, were led by a psychologist. Whether those results carry over to a practitioner holding only a short certificate has not been tested. How training for unlicensed practices can be judged is the subject of the library’s piece on practitioner training.

Questions to ask, and when to see a clinician first

Questions worth putting to any hypnosis provider:

1. What health license do you hold, and does your hypnosis certification require one?
2. Do you follow a published protocol for my problem, such as a gut-directed program for IBS, and how many sessions does it involve?
3. Will any session try to recover or explore memories? A yes is the clearest warning sign the evidence supports.
4. What do you do if a client becomes distressed, confused or detached during a session?
5. Is this part of a treatment plan coordinated with my physician or psychologist, or a stand-alone service?

Some situations call for a licensed clinician before anyone else. A history of psychosis, a dissociative disorder or post-traumatic stress disorder is one, given the case reports and the dissociation research above. Lasting confusion, gaps in memory or a sense of being controlled after a stage show is another. And IBS is a diagnosis a clinician makes after checking for other causes; the hypnotherapy trials enrolled people who already had that diagnosis.

The most useful distinction

Hypnosis for a medical procedure, or for diagnosed and hard-to-treat IBS, delivered by a licensed clinician using a defined protocol, is the version with guideline support. Hypnosis used to dig up memories is the version with documented evidence of harm. A state registration card, where one exists, tells you nothing about which of the two you are getting.

Sources

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