Who Should Be Cautious About Psychedelics? Conditions and Medications to Discuss Before You Prepare

Short answer: Psychedelics are not suitable for everyone. Programmes commonly treat a history of psychosis or bipolar disorder, serious heart conditions, epilepsy, pregnancy, and certain medicines such as lithium, MAOIs and some antidepressants with caution. Do not stop or change prescribed medication yourself; ask the prescribing clinician before you plan anything.

Psymerge doesn't offer substances, retreats or medical advice. This page is education so you can have a better conversation with your doctor. Laws on psychedelic substances differ by country and region, so check local law.

If you take medication or have a health condition, it's worth knowing that some people are told "not now" or "not at all". That isn't a judgement about you. It's what careful screening is for.

Here's what the official and research sources say, in plain words, and what to ask your own prescriber. Where evidence is thin or mixed, we say so.

Why screening matters

Psychedelics can change perception, thinking and mood in strong ways. The US FDA, in its 2026 guidance for researchers, says these drugs "can cause intense perceptual disturbances and alterations in consciousness that can last for several hours or days", and that people may remain in a vulnerable state for several hours or longer [2]. That is guidance for clinical trials, not for individuals. But it explains why trials screen carefully and monitor participants.

Research studies commonly exclude some people. A 2025 consensus statement from the US National Network of Depression Centers notes that research participants are screened for exclusions such as bipolar disorder, psychosis and substance use disorder [3].

Outside research, practice varies a lot. A 2026 interview study of 49 retreat organisations (a convenience sample, self-reported) found that all 49 collected medical histories and 36 excluded people with some conditions. Practices differed widely, and the authors called for best-practice guidelines [1]. That is why it helps to know what to ask. See also how to choose a psychedelic retreat.

Conditions that often call for caution

These are not diagnoses and not a complete list. They are the ones that came up most in the sources we read.

Psychosis and bipolar disorder

In the 2026 retreat study, psychosis was the most common exclusion (24 of 49 organisations), and bipolar disorder was excluded by 16 of 49, about a third [1]. In Oregon's regulated psilocybin programme, a person who has been diagnosed with active psychosis at any time may be found ineligible [7].

Bipolar disorder, according to the US National Institute of Mental Health, "causes clear shifts in a person's mood, energy, activity levels, and concentration", including manic episodes and depressive episodes [4]. The NNDC consensus statement says the risk that psychedelics could trigger a manic or mixed episode in people with bipolar spectrum disorder is "not well known". It cites case reports, and notes there are no studies in people with bipolar I [3].

The Irish HSE also says psilocybin can cause or worsen mental-health difficulties, with a higher risk if you or your family have a history of them [14].

Heart conditions and blood pressure

In the retreat study, 17 organisations excluded cardiovascular conditions and 8 excluded hypertension [1]. The NNDC consensus statement lists potential cardiovascular vulnerabilities among the known risks [3]. If you have a heart condition or high blood pressure, ask your cardiologist or GP before you plan anything.

Epilepsy and seizures

Seven of the 49 retreat organisations excluded epilepsy or seizures [1]. The evidence is thin. A 2024 scoping review of 16 human and 11 animal publications found psychedelics may not raise seizure risk in healthy people who aren't taking other drugs, but that combining them with lithium or kambo could. The review itself says its findings have limited external validity [12]. If you've had seizures, this is a conversation for your neurologist.

Pregnancy

Six of the 49 retreat organisations excluded pregnancy [1]. The sources we opened don't cover pregnancy in clinical detail, so we make no other claim. If you're pregnant, or might be, talk to your midwife or doctor.

Substance use, crisis and thoughts of self-harm

Oregon lists thoughts of harming yourself or others as a reason a client may be found ineligible [7]. The NNDC statement notes that suicidal ideation appeared among serious adverse events in phase-II trials, and that expectation management matters [3]. If you're in crisis now, skip this page and see "If you need help now" at the end.

Medications to ask your prescriber about

This is a list of topics for a conversation. It isn't instructions. What matters for you depends on the exact medicine, how long you've taken it, your health and your plan. Only your prescriber can weigh that.

The NHS says it plainly: "Do not stop taking an antidepressant suddenly or without talking to your doctor first." Stopping can bring withdrawal symptoms, and some can be severe. If you want to come off a medicine, your doctor helps you plan how to reduce it gradually, usually over several weeks or months [5]. The Royal College of Psychiatrists gives the same advice [6].

Antidepressants (SSRIs, SNRIs and others)

What we can say with confidence is that this is an open question.

• The FDA says that, "although more research is needed", taking SSRIs, SNRIs or MAOIs for three weeks or more "may reduce the subjective effects" of psychedelics, and that tricyclic antidepressants or lithium for that long "may potentiate" them, "creating a potential psychiatric safety concern" [2].
• A small open-label study of 19 people with treatment-resistant depression who stayed on a stable SSRI while having psilocybin could not settle the question. It had no comparison group, and the authors called for a larger controlled trial [8].
• An exploratory re-analysis of a trial found that, in the psilocybin group, people who had stopped SSRIs or SNRIs before the trial had a smaller treatment effect than people who had not been on them. The acute experience itself did not differ. The authors stressed that this was "hypothesis generating" and that a controlled trial was "urgently required" [9].
• An online survey, based on 611 reports of taking psilocybin mushrooms while on an antidepressant (self-recalled, online), estimated the chance of reporting weaker-than-expected effects at about 0.47 for SSRIs and 0.29 for bupropion [11].

So: the evidence is mixed, small and often observational. It doesn't tell anyone what to do.

What we can add is that stopping an antidepressant isn't a neutral step. A 2024 review of 79 studies in The Lancet Psychiatry found 31% of people had at least one discontinuation symptom after stopping antidepressants, against 17% after stopping placebo, with large differences between studies [10]. The NNDC authors say that tapering or stopping "should be carried out in a safe, well-supervised setting by a provider with the expertise", and that it may increase the risk of worsening depression [3].

Programmes differ widely. In the 2026 retreat study, 43 of 49 required or recommended stopping some medicines, with timelines from one day to more than six weeks, and only 7 said they consulted medical professionals when setting those rules [1]. That variation is a reason to take the question to your own prescriber, not to a retreat's website.

MAOIs, and ayahuasca in particular

Ayahuasca contains compounds that inhibit an enzyme called MAO. A 2017 review by pharmacists in Mental Health Clinician says that, because of this, ayahuasca "carries a higher risk of drug interactions than other psychedelics", and that it should be avoided with several serotonergic medicines, including some antidepressants [13]. The same review notes that effects of food high in tyramine haven't been described in ayahuasca users, but that experience with prescription MAOIs suggests a higher risk of hypertensive crisis [13].

The FDA says that MAOIs combined with MDMA or other amphetamine-based psychedelics "can produce a life-threatening hypertensive crisis" [2]. The NHS notes that MAOIs are now rarely used to treat depression [5], so many people won't take one. If you do, or you aren't sure what class your medicine belongs to, ask your prescriber or pharmacist.

If you're considering an ayahuasca retreat, the ayahuasca preparation pages give more background.

Lithium

Lithium appears in several sources:

• The FDA says taking lithium for three weeks or more "may potentiate" the subjective effects of psychedelics, creating a potential psychiatric safety concern [2].
• Oregon lists recent lithium use as a reason a client may be found ineligible [7].
• The scoping review above says lithium could increase seizure risk [12]. The NNDC statement describes a signal from internet self-reports and says lithium, but not lamotrigine, may increase seizure risk [3]. That is weak evidence, which is why the question belongs with your prescriber.

Other medicines

Benzodiazepines, antipsychotics, other mood stabilisers, stimulants, blood-pressure medicines and others also belong on the list you take to your prescriber. We didn't find an official source that addresses each of these for a general audience, so we make no claims about them. Tell your prescriber or pharmacist about everything you take, including over-the-counter and herbal products. The NHS, for example, notes that some antidepressants don't mix well with alcohol, some foods, some other medicines, drugs like cannabis or ketamine, or the herbal remedy St John's wort [5].

What good screening looks like

Careful screening usually means a health and medication history reviewed by someone trained to read it, a conversation rather than just a form, a real chance of being told no, and a request to involve your own doctor. In Oregon, facilitators can decline a client for any reason [7]. In clinical trials, the FDA expects the lead monitor to be a licensed health care provider [2]. Those are regulated and research settings, not a benchmark for every retreat. Our guide on how to choose a psychedelic retreat lists questions you can ask.

Questions to ask your prescriber

Bring this list to your appointment. Say plainly what you're considering, even if you aren't sure it's legal where you are. Your clinician is there to talk about your health.

1. I'm thinking about a psychedelic experience. Are any of my conditions a reason for caution?
2. Could any medicine I take interact with it? Please check each one, including over-the-counter and herbal products.
3. Is there anything about my heart, blood pressure or history of seizures I should discuss with a specialist?
4. If a programme asks me to stop a medicine, who should decide, and how would that be done safely?
5. What are the risks of stopping this medicine, and what would be the signs that something was going wrong?
6. Who should I contact if I feel worse afterwards, and how fast can I be seen?
7. Is it better to wait? What would need to change first?
8. Is there anything in my personal or family history, such as psychosis, bipolar disorder or seizures, that I should mention to anyone running a programme?
9. Can you write down what you advised, in case a facilitator asks?

If you can't go ahead

Sometimes the answer is "not now". That doesn't close the door on looking after yourself.

You can still do preparation work that doesn't involve any substance: thinking about what you're looking for, what support you have, and how you want to make sense of things. Talking therapies and ordinary mental-health care are options your clinician can discuss. If you're already having a hard time, see a licensed clinician rather than waiting.

How a guide can help, and what they can't do

A preparation or integration guide on Psymerge can help you think through your intentions, your questions for your doctor, and your support plan. Guides are independent professionals. They don't provide medical advice, don't replace your prescriber, and don't supply substances. Psymerge doesn't screen people medically and isn't a crisis service.

Find an independent preparation guide →

If you need help now

If you feel unwell or unsafe, call your local emergency number. The HSE (Ireland) lists signs that need emergency help, including seizures, breathing problems, chest pain, severe panic and thoughts of suicide [14]. In the US you can call or text 988. In the UK and Ireland, Samaritans is on 116 123. Check the number for the country you're in.