Psychedelics are not for everyone or for every moment. Saying so is not alarmism: it is the foundation of any responsible use. The clinical trials that are cited so often exclude a significant share of the people who apply, precisely because in certain profiles the risk clearly outweighs the possible benefit.
This article summarizes the most important contraindications according to the available evidence. It is general information and is no substitute for a medical assessment. If you recognize yourself in any of these points, the prudent thing is not to use and to talk to a healthcare professional.
A history of psychosis or schizophrenia
This is the best-known and best-documented contraindication. People with a psychotic disorder, or who have had psychotic episodes, are left out of practically every study with psilocybin, LSD or ayahuasca.
A review and meta-analysis published in Molecular Psychiatry analyzed cases of psychedelic-induced psychosis. In clinical trials with screened participants, the incidence was low: between 0.2% and 0.6%. In people with schizophrenia, by contrast, 3.8% developed long-lasting psychotic symptoms. And among those who had suffered a psychedelic-induced psychotic episode, around 13% later received a diagnosis of schizophrenia.
The authors warn that many of the studies are of low quality and recommend caution. The practical reading is clear: the risk is small in people with no prior vulnerability and much greater when that vulnerability exists.
Bipolar disorder
Psychedelics can trigger episodes of mania or mixed states in people with bipolar disorder. A consensus statement by specialists published in eClinicalMedicine notes that there are case reports confirming this risk and that no studies exist in people with bipolar I disorder. For type II there are only pilot studies, carried out under close supervision.
Outside a controlled clinical setting, bipolar disorder is considered a contraindication.
Family history
Having a first-degree relative with schizophrenia, psychosis or bipolar disorder is a common reason for exclusion from trials. The reason is that part of the vulnerability is inherited and may not have shown itself yet, especially in young people.
It does not mean that something is going to happen, but it does mean that the safety margin is narrower. It is one of the most frequently overlooked points.
Cardiovascular problems
Psilocybin, LSD, ayahuasca and especially MDMA raise blood pressure and heart rate for several hours. In a healthy person this is usually a moderate, temporary increase. With poorly controlled hypertension, arrhythmias, heart disease or a history of stroke, that added strain can be dangerous.
The same consensus statement also mentions an open question about repeated use and the heart valves, because of the action of these substances on a specific serotonin receptor. There are no data to confirm it or to rule it out.
Medication that interacts
Some combinations change the effect and others carry serious risks:
- Lithium. In an analysis of reports of combined use, 47% of the 62 cases involving lithium included seizures and 39% required medical attention.
- Monoamine oxidase inhibitors. Ayahuasca already contains them, and combining them with other serotonergic drugs can cause toxicity.
- Antidepressants. They tend to reduce the effects, which leads some people to increase the dose or to stop their treatment on their own. Both are a bad idea.
We go into detail in psychedelics and antidepressants: what is known about the interactions. Never stop a medication without talking to the person who prescribed it.
Pregnancy and breastfeeding
There are no safety studies in pregnancy or breastfeeding, and for ethical reasons there are unlikely to be any. In the absence of data, the recommendation is not to use.
Epilepsy and a history of seizures
People with epilepsy or a history of seizures are usually excluded from trials. The evidence is limited, but the potential risk is serious enough to proceed with caution and always seek advice beforehand.
Acute emotional crisis
A contraindication is not always a diagnosis. Sometimes it is the timing. It is best to wait if:
- You are going through a recent crisis, a very fresh loss or a breakup.
- You are having thoughts of harming yourself.
- You have gone weeks without sleeping well or with very high anxiety.
- You are looking for an urgent solution to a serious problem.
- You feel you are doing it because of pressure from other people.
Psychedelics amplify what is already present. At a time of great fragility, that can overwhelm you instead of helping. If you are going through a situation like this, seek professional support first.
Young people
The brain keeps maturing until past the age of twenty, and many psychotic disorders first appear precisely in late adolescence and the early years of adulthood. That is why clinical trials only include adults and why prudence advises waiting.
When the context is missing
Some risks depend not on your health but on the conditions:
- Untested substances or substances of doubtful origin.
- High doses with no prior experience.
- Mixing with alcohol or other drugs.
- Being alone or with people you do not trust.
- Noisy, unfamiliar or unsafe environments.
A good context does not cancel out a medical contraindication, but a bad context can turn something into a problem that did not need to be one. Here we explain what set and setting are.
What to do if you have doubts
- Talk frankly with your doctor or your psychiatrist. It is health information, not a confession.
- Do not hide your history or your medication from whoever is going to accompany you.
- Be wary of any facilitator who does not ask about your health before agreeing to accompany you.
- If in doubt, wait. The possibility of doing it later does not go away.
And remember that deciding not to take anything is also a valid decision. Emotional work, meditation, breathwork and support do not require any substance.
Support that starts with safety
At RILOFU we do not sell or supply substances, and we do not encourage anyone to use. We support people who want to prepare for, understand or integrate their experiences, and that includes saying clearly when something is not a good idea.
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Sources
- Reconsidering evidence for psychedelic-induced psychosis: an overview of reviews, a systematic review, and meta-analysis of human studies. Molecular Psychiatry.
- Considerations and cautions for the integration of psilocybin into routine clinical care: a consensus statement. eClinicalMedicine, 2025.
- Classic psychedelic coadministration with lithium, but not lamotrigine, is associated with seizures. Pharmacopsychiatry, 2021.