In short: in clinical research, a psychedelic “treatment” is much more than taking a substance. It usually includes medical and psychological screening, several preparation sessions, a long supervised dosing session, and follow-up sessions to make sense of the experience. Ketamine treatment is shorter per session but usually repeated.
This chapter describes how treatment is structured in clinical trials. Programs outside research vary widely.
1. Screening and assessment
Before anyone takes part, researchers check whether it’s likely to be safe and appropriate:
- A medical history, physical exam, and often blood tests and a heart check (ECG)
- A psychiatric assessment, including personal and family history of psychosis and bipolar disorder
- A review of current medicines, some of which may need to be tapered under medical supervision
- Questionnaires to measure symptoms before treatment
See Safety for the most common reasons people are excluded.
2. Preparation
In psilocybin and MDMA trials, participants usually have several preparation sessions with the therapists who’ll be present during dosing. These sessions build trust, set intentions, and explain what the experience may feel like, including that it can be difficult. People also learn practical strategies, such as leaning into difficult feelings rather than fighting them.
3. The dosing session
Psilocybin (typical research format):
- A calm, living-room-style room, not a clinical ward
- Usually two trained facilitators present throughout
- The participant often lies down with eyeshades and a curated music playlist
- Effects start within about an hour and last around six hours, so sessions typically take most of a day
- Blood pressure and heart rate are checked, and participants go home with someone else afterwards
MDMA-assisted therapy follows a similar structure, with sessions lasting around eight hours. In the phase 3 PTSD trials, participants had three MDMA sessions spaced about a month apart, with talk-therapy sessions in between.1
Ketamine sessions are shorter:
- IV infusions in research typically run about 40 minutes, with monitoring before, during and afterwards
- The dissociative effects usually fade within an hour or two
- Treatment is usually a series, for example two sessions a week for a few weeks. In a 2023 trial comparing ketamine with ECT, participants received ketamine twice a week for three weeks.2
- Esketamine nasal spray is taken in a certified clinic, with monitoring for at least two hours afterwards in the US, and people can’t drive until the next day.
4. Integration
After a psychedelic session, participants usually meet their therapists one or more times to talk about the experience and how it relates to their lives. Many researchers believe this “integration” is an important part of any lasting benefit, especially if psychedelics open a temporary window of brain flexibility (see How it works). How much integration matters hasn’t been tested directly in many trials.
5. How many sessions, and how long effects last
- Psilocybin: trials usually use one or two dosing sessions. Improvements in some trials lasted weeks to months, but in others faded by three months.
- MDMA: usually three sessions in PTSD trials.
- Ketamine: usually a series of six to eight treatments to start. Without ongoing treatment, benefits often fade within weeks, so many programs offer occasional “maintenance” sessions. Research on the best long-term schedule is ongoing.
Questions people often ask a provider
- What training do the people running the session have?
- How will I be screened, and what happens if I’m not suitable?
- What support is there during the session and afterwards?
- What happens if I have a difficult experience or feel worse later?
- Is this part of a clinical trial, an approved treatment, or off-label use?
This chapter is educational. It isn’t medical advice, and it isn’t a recommendation of any program or provider.