What does Science say about Hypnosis?

What is best documented

Pain and hypnosedation

This is the most solid area, by far.

Hypnosedation reduces the use of painkillers and sedatives during medical procedures: dental extractions, biopsies, colonoscopies, catheter procedures, and even some major operations. The measured benefits also concern patients' anxiety, and the length and cost of the procedures.

Two important clarifications. This is practised in a care setting, by health professionals: it is not what we do, and it never replaces conventional medical care. It is also the only area where the degree of individual responsiveness to hypnosis seems to matter clearly.

Irritable bowel syndrome

The second area retained by Inserm. Regular hypnotherapy sessions limit digestive symptoms: abdominal pain, bloating, alternating diarrhoea and constipation.

It is the only reason for consulting a hypnotherapist, in the everyday sense of the term, for which the data are considered sufficient, and it is often overlooked by the people concerned. We have a page on it: hypnosis for irritable bowel syndrome.

What has been studied with disappointing results

It has to be said, including when it concerns reasons why people come to see us.

Smoking cessation. Inserm puts the data in the "insufficient, or even disappointing" category. Other reviews, including a 2019 Cochrane review, conclude that nothing shows hypnosis does better than other approaches to quitting.

That does not mean it works for no one: some people stop smoking after one session, and that is real. It means that we cannot claim hypnosis is the cause, rather than the decision already made, the timing, or the fact of having put money on the table.

Childbirth pain. Same verdict in the report, which may come as a surprise given how popular hypnosis-based birth preparation is. The reported benefits concern the experience of the birth more than the measured intensity of pain.

Why hypnosis is hard to evaluate

The Inserm report itself points to a fundamental difficulty, and it is worth understanding rather than using as an excuse.

There is no placebo hypnosis. You can give a pill with no active ingredient. You cannot give a hypnosis session without hypnosis: the relationship, the attention, the voice, the time spent are all part of the intervention.

The intervention is not standardised. Two practitioners do not do the same thing, and a good practitioner does not do the same thing with two different people. That is a strength in the consulting room and a methodological problem in research.

The outcome measures. How do you measure "feeling better"? A pain score can be measured. A calmer relationship with your own body, much less so.

The authors also note that qualitative studies lead to putting the negative conclusions into perspective: the benefits patients describe are not always the ones the protocols measure.

What this argument does not allow is dismissing every unfavourable result. If the difficulty of evaluation were used never to conclude anything, it would no longer be an argument but a way out.

Hypnosis and memories: the most serious question

It is the strongest criticism levelled at hypnosis, and we would rather address it than avoid it.

The problem

The hypnotic state increases the availability of imagination and responsiveness to suggestion. These two features, which are what make it useful, produce a documented side effect: content can emerge with a complete sense of reality without matching what actually happened.

The problem is not that the person is lying. It is that they have no way, from the inside, of telling a memory from a reconstruction. And a detail recalled under hypnosis then tends to be remembered with greater certainty than before, even when it is false.

The question has given rise to major controversies, particularly around "recovered memories" of abuse, with considerable legal and family consequences. Many jurisdictions today restrict or exclude testimony obtained under hypnosis. In Canada, since R. v. Trochym in 2007, the Supreme Court has presumed testimony given after a hypnosis session to be inadmissible.

What this means in practice

• A serious practitioner does not go looking for forgotten memories. It is not a method for investigating the past.
• What emerges in a session is never presented as established truth. It has value for what it says about you today, not as evidence.
• Leading questions are avoided, and that is a skill that has to be learned.
• If you are offered a "regression" supposed to reveal what happened to you, or past lives presented as facts, ask questions. Our page which type of hypnosis to choose helps you find your way among the approaches.

And if memories come up anyway?

It happens, and it is not abnormal. The work then consists in supporting what you are feeling now, without turning the session into an investigation, and without any conclusion being drawn about your history.

If what comes up concerns serious events, it calls for specialised support and, where appropriate, legal proceedings that will go through channels other than hypnosis.

So, should you try it?

What science allows us to say honestly: the hypnotic state exists and can be measured. The risks are limited. The effect on pain and on irritable bowel syndrome is established. The effect on anxiety is well supported, especially alongside other approaches. For most other reasons for consulting, there are no solid data, either way.

What remains true in every case: hypnosis replaces no diagnosis and no treatment, it is meant as a complement, and if your situation calls for a doctor first, that is where to start. The data presented here concern the populations studied: they say nothing in advance about what you will experience.

A question about what is documented for your situation? Write to us, and we will answer without embellishing: ask us your question. When you are ready, book an appointment; we will come back to it at the preliminary conversation, before any session. Wherever you are in the world, video consultation offers the same preliminary conversation and the same session as in the consulting room. We see people this way from France, Quebec, Morocco and well beyond. Here is how it works.