Is Psilocybin Therapy Safe? What the Research Says, and How We Screen, Prepare and Hold Every Session

What “safe” means here

Safety is usually the second question people ask us, right after legality, and often it is the question underneath all the others. People want to know whether they will be okay, who will be with them, and what happens if something feels like too much. Those questions deserve specifics rather than reassurance, so this page gives you the numbers and the rules, and then lets you decide.

Two things are true at once. Psilocybin has very low physical toxicity and no known pattern of dependence, which is why it scores at the bottom of every comparative harm ranking. And a strong dose taken by the wrong person, or in the wrong setting, can do real harm. The difference between those two sentences is screening, preparation, the person in the room, and what happens afterward. That is the whole job of a healing center.

What the research says

The clearest recent picture comes from a systematic review and meta-analysis published in JAMA Psychiatry in 2024 by a team at Johns Hopkins. It pooled 214 studies of classic psychedelics, 114 of them with usable adverse event data covering 3,504 participants. Serious adverse events were reported for no healthy participants and for roughly 4 percent of participants with pre-existing psychiatric conditions, where they included worsening depression, suicidal behavior, psychosis and seizures. In contemporary research settings there were no deaths by suicide, no persistent psychotic disorders and no cases of hallucinogen persisting perception disorder. The most common side effects were headache, anxiety during the session, nausea, fatigue and dizziness. The authors’ conclusion was that classic psychedelics are generally well tolerated in clinical settings, and that monitoring and reporting still need to improve.¹

Earlier work points the same way. A pooled analysis of 110 healthy volunteers who received psilocybin in eight controlled studies found that acute reactions such as strong anxiety or panic occurred only at the two highest doses, in a small proportion of people, and every one of them was managed with interpersonal support rather than medication. Follow-up found no subsequent drug abuse, no persisting perception problems and no prolonged psychosis in any participant.² The two largest recent depression trials, a phase 2 study in the New England Journal of Medicine and a randomized trial in JAMA, reported side effects in most participants, mainly headache, nausea and dizziness on the day, and in the treatment-resistant group some participants experienced suicidal thoughts in every dose arm, which is why screening for current suicidality matters so much.^3,4 In the 2010 Lancet analysis that ranked 20 drugs by harm to users and to others, psilocybin mushrooms scored lowest of all, 5 on a 100-point scale against 72 for alcohol.⁵

The safety guidelines that the whole field works from were written at Johns Hopkins in 2008 and they are, in short, the model Numia runs: careful screening for personal or family history of psychosis, preparation before the session, a trained person present throughout, a calm and comfortable setting, and follow-up afterward.⁶

Where the real risks are

Four risks account for nearly everything that goes wrong with psilocybin, and each has a specific answer.

Distress during the session. Fear, grief, confusion or a sense of losing control can arise, sometimes intensely. In a survey of 1,993 people describing their most difficult mushroom experience, most of them taken recreationally, 39 percent ranked it among the five most challenging experiences of their lives, and 11 percent put themselves or someone else at risk of physical harm. The factors that raised that risk were a higher dose, a longer and harder experience, and the absence of physical comfort and social support.⁷ That last finding is the case for a licensed center in one sentence: the same experience with a trained therapist beside you, in a room designed for it, is a different event.

Medication interactions. Lithium is the clearest hazard. In an analysis of published experience reports, 47 percent of 62 accounts that combined a classic psychedelic with lithium involved a seizure; none of 34 reports involving lamotrigine did.⁸ Common antidepressants are a different kind of issue. SSRIs and SNRIs do not appear to make psilocybin dangerous, but they blunt it, with roughly a coin-flip chance of a weaker than expected effect, and the dampening can last up to three months after stopping.^9,10 We never tell anyone to stop a medication on their own; that conversation belongs with the prescriber, and we help you have it.

Cardiovascular strain. Psilocybin temporarily raises heart rate and blood pressure. For a healthy heart that is a non-event; for someone with uncontrolled hypertension, a recent cardiac event or certain arrhythmias it can matter, which is why heart history is part of every screening and why we ask for a physician’s clearance when it is warranted.¹¹

Psychosis in people predisposed to it. The one group the field has excluded from the beginning is people with a personal or close family history of psychosis, schizophrenia or bipolar I disorder. We follow that line without exception.

How we screen

Screening at Numia happens in layers, and no one reaches journey day without passing through all of them.

Step	What happens	What it catches
Free 15-minute consultation	A conversation with a member of our team about what is bringing you here, the basics of your health history, and whether this path makes sense to explore.	Clear exclusions, timing questions, and whether another kind of support should come first.
Fit call with your therapist	A 30-minute conversation with the licensed therapist chosen for you, who would be with you from preparation through integration.	Goals, history, current stressors, and whether the two of you want to do this work together.
Health and medication history	A full intake in our secure clinical record: medical conditions, psychiatric history, current medications and supplements, and prior experiences with psychedelics.	Lithium, cardiovascular conditions, psychosis history, pregnancy, current crisis, and anything that needs a prescriber’s input.
Colorado’s required safety screening	The screening the state requires of every facilitator, using a tool that reflects accepted standards of practice, documented in your record.	Risk factors that require a referral, a medical clearance or a consultation with a licensed provider before we proceed.
Medical clearance when warranted	If your history raises a flag, we ask for clearance or a consultation with a provider licensed to treat that condition, exactly as the rules require.	Heart conditions, complex medication regimens, and recent psychiatric care.
Preparation sessions	One-hour sessions before journey day where intentions, fears, the dose and the practical plan for the day are set together.	Anything that changed since intake, and a plan for what to do if the session gets hard.

Some people are turned away at these steps, and we say so plainly when we do. Colorado’s screening rule does not list specific diagnoses; it requires a screening tool that reflects generally accepted standards of practice, and when risk factors appear it requires one of three things before services can go ahead: a referral from a healthcare provider, medical clearance from your own provider, or a consultation and risk review with a provider licensed to treat the condition in question.¹² We build our screening around the Johns Hopkins guidelines and that rule.

What Colorado requires, and how it shows up on the day

Numia is a licensed healing center under the Colorado Natural Medicine Health Act, and the rules that govern facilitators (4 CCR 755-1) are specific about safety. The ones you will notice:

• Informed consent must include a full and accurate description of the range of possible effects of the medicine before you take it (Rule 6.16(D)).
• Monitoring. During the session your facilitator must take all reasonable efforts to prevent physical and psychological harm, including monitoring your vital signs, hydration and psychological well-being (Rule 6.17(C)).
• Staying put. You are instructed not to leave the administration space during the session, and the facilitator is responsible for making sure that holds (Rule 6.17(D)).
• Time. A full-dose session must last at least five hours and continue until you are showing no obvious adverse effects (Rule 6.17(F)).
• Group size. Group sessions are capped at four participants per facilitator (Rule 6.17(G)).
• Getting home. A transportation plan is part of your record, which is a formal way of saying you will not be driving yourself home (Rule 6.3(B)).
• Reporting. Any serious adverse health event must be reported to the state within 24 hours (Rule 6.23(B)).
• Integration. Your first integration session cannot carry a separate fee (Rule 6.19(A)).

The rule text is public on the Colorado Office of Natural Medicine Licensure site, linked in the sources below.

The medicine itself comes from a Colorado-licensed cultivator and is tested by a state-licensed laboratory before it reaches us. Your dose is decided with you in preparation, not on the day, and the medicine fee is billed in advance as the state now requires.

What journey day looks like

You arrive at our center in the heart of Denver, a place that feels like a calm, beautiful home rather than a clinic, because your nervous system reads the room long before your mind does. Your therapist is with you from the moment you walk in until the medicine has fully resolved, typically five to eight hours, and the room is never unstaffed. Our therapists have guided over 200 legal psilocybin sessions this way. Phones and belongings stay with our support staff so nothing pulls at you. Music, light and the pace of the day are set for you, and your therapist checks on you physically and emotionally throughout, including the checks the state requires.

Our model is the clinical facilitator therapist: a licensed mental health professional (LCSW, LPC, PsyD, LMFT) who also holds Colorado facilitator licensure. Colorado licenses facilitators with and without a clinical background, and our guide to therapist-led versus facilitator-led psilocybin therapy explains what that difference means for screening and for what happens when a session gets hard.

If the session gets hard

It sometimes does, and this is worth saying clearly. Difficult emotions surface, and that is often where the healing lives. Your therapist’s job in those moments is to stay steady, keep you physically and emotionally safe, and help you stay with what is unfolding rather than fight it, with a hand to hold, a change of music, a few words, or simply presence. In the pooled research on healthy volunteers, every acute reaction was resolved this way, through interpersonal support, and none required medication.² That matches our own experience. Trauma is known to live in the body, and sometimes what needs to move cannot be reached with words alone; a safe, held setting is what allows it to move gently. The grounding breath and phrase Carolina teaches in preparation exists for exactly these moments, and you will have practiced it before you need it.

After the session

Safety does not end when the medicine wears off. Most people feel tired and unusually open for a day or two, and a headache the next morning is common. Two one-hour integration sessions follow, the first typically the day after and the second about two weeks later, which can be held over telehealth. These are where the experience gets turned into something you can use, and they are also where we watch for anything that needs more support. Our integration page describes how those sessions run. If something feels wrong between sessions, you have your therapist’s contact and you use it.

Frequently asked questions

This article is educational and does not replace medical advice. Eligibility is assessed individually. Numia Healing Center is licensed by the Colorado Natural Medicine Division, license NMHC-00022. Colorado rule references are current as of September 2026.

Sources

1. Hinkle JT, Graziosi M, Nayak SM, Yaden DB. Adverse events in studies of classic psychedelics: a systematic review and meta-analysis. JAMA Psychiatry. 2024;81(12):1225-1235. PubMed
2. Studerus E, Kometer M, Hasler F, Vollenweider FX. Acute, subacute and long-term subjective effects of psilocybin in healthy humans: a pooled analysis of experimental studies. J Psychopharmacol. 2011;25(11):1434-1452. PubMed
3. Goodwin GM, Aaronson ST, Alvarez O, et al. Single-dose psilocybin for a treatment-resistant episode of major depression. N Engl J Med. 2022;387(18):1637-1648. PubMed
4. Raison CL, Sanacora G, Woolley J, et al. Single-dose psilocybin treatment for major depressive disorder: a randomized clinical trial. JAMA. 2023;330(9):843-853. PubMed
5. Nutt DJ, King LA, Phillips LD. Drug harms in the UK: a multicriteria decision analysis. Lancet. 2010;376(9752):1558-1565. PubMed
6. Johnson MW, Richards WA, Griffiths RR. Human hallucinogen research: guidelines for safety. J Psychopharmacol. 2008;22(6):603-620. PubMed
7. Carbonaro TM, Bradstreet MP, Barrett FS, et al. Survey study of challenging experiences after ingesting psilocybin mushrooms: acute and enduring positive and negative consequences. J Psychopharmacol. 2016;30(12):1268-1278. PubMed
8. Nayak SM, Gukasyan N, Barrett FS, Erowid E, Erowid F, Griffiths RR. Classic psychedelic coadministration with lithium, but not lamotrigine, is associated with seizures. Pharmacopsychiatry. 2021;54(5):240-245. PubMed
9. Becker AM, Holze F, Grandinetti T, et al. Acute effects of psilocybin after escitalopram or placebo pretreatment in a randomized, double-blind, placebo-controlled, crossover study in healthy subjects. Clin Pharmacol Ther. 2022;111(4):886-895. PubMed
10. Gukasyan N, Griffiths RR, Yaden DB, Antoine DG, Nayak SM. Attenuation of psilocybin mushroom effects during and after SSRI/SNRI antidepressant use. J Psychopharmacol. 2023;37(7):707-716. PubMed
11. Wsół A. Cardiovascular safety of psychedelic medicine: current status and future directions. Pharmacol Rep. 2023;75(6):1362-1380. PubMed
12. Colorado Office of Natural Medicine Licensure, Rules and Regulations, 4 CCR 755-1, Rule 6 (Standards of Practice): 6.3(B), 6.16, 6.17, 6.19, 6.23. dpo.colorado.gov/NaturalMedicine. Rule text as published by Cornell Law School’s Legal Information Institute: 4 CCR 755-1-6. Healing center and product rules: Colorado Natural Medicine Division.