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  • Are truffles and psilocybin safe?
    Despite the fact that population and experimental studies did not find statistically significant detrimental effects on mental health associated with use of psychedelics, modern researchers take extra precautions when working with certain populations, in which anecdotal reports warrant potential dangers. Specifically, because psychedelics induce mental states that are very unusual for our waking consciousness, effectively occasioning intense emotions and profound shifts in perception, they are not recommended for people with history of psychosis-spectrum disorders (schizophrenia, schizoaffective and bipolar disorder), acute psychological trauma and an extra caution advised to people who recognize themselves as being in very emotionally unstable period. This is why, at Katharsis, we pay close attention to screening before accepting our guests. It is worth noting that even if our team does not recommend you joining the retreat, there are other available treatment options that must not be ruled out.
  • Who is eligible for the retreats?
    Every human being is unique, and so are psychological struggles one may encounter in their lifetime. In terms of mental health, psychedelic therapy appears to provide most promising evidence for treating conditions associated with reduced emotional and psychological flexibility, such as, for example, depression, anxiety disorders, occupational burnout and addictions. As stated on our disclaimer, we do not offer medical treatment for these conditions at this time, however we do offer a safe space for healing through what life has burdened you with so far, and continue to amalgamate professional therapeutic work and ongoing scientific research into our practices.
  • How do I know if I am safe to participate in the retreat?
    Anyone wanting to take part in one of our programs is required to first go through our safety and eligibility screening which is carried out by our panel of physicians. First you will be asked to fill out a questionnaire regarding your physical and mental health online. After this, we will set up an online consultation with one of our physicians where we make a thorough assessment of your physical and mental health status to declare if you are safe to participate or not. For more detail regarding the process, please see the guest journey overview.
  • What contraindications are there for using truffles?
    Psychedelics and psilocybin have tremendous healing potential, but they are certainly no magic do-it-all pill. Working with psilocybin containing truffles is not suitable and may be dangerous for certain medical and psychiatric conditions. These conditions include, but are not limited to Active or history of psychosis Family history of psychosis Actively suicidal Dissociative disorders Active Mania or Major Depressive Disorder Pregnancy Poorly controlled hypertension Poorly controlled heart failure Recent traumatic brain injury All of our clients will go through a psychiatric evaluation to declare their fitness level to work with the truffles.
  • What medications are contraindicated with psilocybin?
    There are certain pharmaceutical medications and plant remedies that are not safe to mix with psilocybin containing truffles. In general these are serotonergic compounds such as most antidepressants, but there are numerous other medications which may be unsafe. This is why anyone aiming at participating in one of our retreats will go through a medical screening with our panel of medical doctors, where we will go through your medication list and look for any potential dangerous interactions.
  • I’ve heard about bad trips. Are they dangerous? What are the chances of me having a scary trip?
    ‘Bad trips’ are often what is most feared by those wanting to use psychedelic substances. Whilst it is true that psychedelics can induce major processes which may be considered ‘scary’, ‘intense’ and ‘bad’, however, this is often where the breakthroughs and healing occurs. Try to think of this just like a form of psychotherapy. Going in for therapy is often difficult, resurfaces emotions and memories of difficult events and requires you to go through some of your past. However, this is often what is needed to process and move on. At Katharsis, we will be creating a safe, loving and non-judgemental environment for you to be in and we will have facilitators there to aid you through any anxiety or emotions that surface.
  • What are Truffles and Psilocybin?
    Psychoactive truffles represent masses of mycelium, also called sclerotia, which are the specialized structures on the mushroom plant that contain reserve materials important for the fungus to survive in unsuitable conditions. They contain a substance called psilocybin. This is a classical psychedelic molecule currently being tested in clinical trials focusing on patients with a major focus on depression, anxiety, addiction and other mental health conditions.
  • Have these substances been researched and what are the typical indications for psychedelic treatment?
    Psychedelics were the focus of psychiatric research in the first half of the 20th century before their prohibition. Despite the fact that today we use different standards for recognising medical value of a treatment, modern attempts to re-visit the old studies concluded on their high medical value and acceptable risk profile 8,9. By the moment of writing, there are dozens of modern (completed or ongoing) small-scale clinical trials investigating the medical value of classical psychedelics (and psilocybin, in particular) for the treatment of depression, anxiety and addictions. Yet, it is important to recognise, that even despite preliminary evidence for their efficacy and safety, psychedelic-assisted treatment remains experimental and more large-scale studies are needed in this vein for them to be recognised by psychiatry major as an officially viable treatment option.
  • Why psychedelic medicine?
    ‘’No problem can be solved from the same level of consciousness that created it. - Albert Einstein’’ Psychedelic medicines have tremendous potential for healing when combined with the right set and setting, and adequate therapeutic support. So, what are the benefits of psilocybin? How can we categorize their therapeutic action? One way is to categorize these effects into the three part human model: body, mind and soul. Apart from direct action on the brain's capacity for change (aka neuroplasticity) 4, psychedelics appear to promote more flexible patterns of neural activity, widening the repertoire of the functional states that the brain can be in over a fixed amount of time 5. One hypothesis is that this happens through quieting the Default Mode Network (DMN) of the brain, that we seemingly use to operate in our ‘normal state of conciousness’, having a major function in our sense of self ‘the ego’ and our social understanding of others. This is physiologically the opposite to what we typically observe in patients suffering from some psychiatric disorders like depression, which is associated with neurophysiological 6 and cognitive inflexibility 7, allowing for rigid mental states of rumination and self-defeating thoughts. “Brain imaging studies suggest that when psychedelics are absorbed they decrease activity in the default mode network. As a result the sense of self appears to temporarily shut down, and thus ruminations may decrease. The brain states observed show similarities to deep meditative states, in which increased activity occurs in pathways that do not normally communicate. This process has been compared to defragmenting a computer. Following this, it appears that the default mode network becomes more cohesive. We think this could be one of the reasons levels of anxiety and depression appear to reduce.” Dr. Simon Ruffell, Psychiatrist and Senior Research Associate at King’s College London Ultimately, the ability of psychedelics to promote neural and behavioral plasticity, provides scientific justification for using these substances as catalysts and/or adjuncts to various forms of behavioral interventions and psychotherapy in particular, by creating a shift in perception. There are dozens of psychological models of psychedelic’s action stemming from various schools of psychology. Some link their effects to the physical and physiological lowering of psychological resistances, and others emphasize the importance of the so-called mystical-type experiences (the profound ineffable experience of owe, interconnectedness with the Universe). At Katharsys, we implement a holistic approach to psychedelic therapy, aligning with state-of-the-art biomedical research and medical-grade professionalism and safety, whilst paying respect to ceremonial use of these powerful substances and recognising limitations of the scientific method. Here, we establish a mutually supportive dialogue between modern medicine, academic science and spirituality to assist you on your journey toward self-discovery and healing.
  • Why should I choose Katharsis Journeys?
    We believe that our approach is very unique in bringing together highly respected healers and qualified medical professionals. We strive to bring together the best of the two worlds, western science and ancient wisdom.
  • What is included in the retreat program?
    The following is included in our total package: An online consultation with one of our doctors for a physical and mental screening Three 60 minute online ‘preparation’ consultations before your arrival Two truffle ceremonies with live music Your stay at the retreat center, including all meals. Choice of single room per request, otherwise shared double room. Yoga Qi Gong Meditation Breathwork Nutritional advice for those who wish Three 60 minute ‘integration’ sessions following the ceremony to help you integrate the experience. Our information booklet which is given to all participants upon booking a retreat Transport to and from the venue from Amsterdam airport
  • What food is served?
    Light vegetarian/vegan food, all made with love and locally sourced products. One of our doctors is also a passionate chef and has training in nutrition. She will talk to you about your food preferences and needs, and will create the menu based on a tailored plan.
  • What music is played?
    We pay very special attention to the music, which we believe is an integral part of the healing process. All of our ceremonies will have professional musicians performing live music. The music is synchronized live to the process. What this means is that instead of a playlist or a band playing through a series of songs at a preset order, the music is synchronized to the energy field in the room and tailored to the stage of the ceremony.
  • What clothes should I bring and what should I wear?
    Bring comfortable, if possible light colored clothes, and anything you would need for a weekend away. Remember to bring any medication and toiletries that you may need.
  • How do I book a retreat?
    The process of booking your stay with us goes following: Complete our online eligibility screening through the ‘book an exploratory call button’ Then, we will arrange an online consultation between one of our physicians and you, where we make a thorough assessment of your physical and mental health status to declare if you are safe to participate or not. This consists of two parts: Part 1 consists of a medical safety check, Part 2 is devoted to mapping your intentions and expectations from working with Psilocybin, and whether what we offer at Katharsis is of benefit for you or not Once we have decided together that this journey is right for you, we can arrange the booking of your place and you can select three time slots in our online calendar for your preparation sessions
  • Payment
    After you complete the health screening questionnaire, we will review your application and given no contraindications to participate, we will send you several slots to let you book a call with one of our physicians. Prior to this call, you are kindly requested to pay a fee of 100€. Should you be deemed fit and your application move forward after the consultation with our doctor, this fee will be deducted from the full payment. In case you do not complete the payment or your application is rejected, this 100€ fee will not be refunded. Please be mindful that shall your application be rejected at this time, it is for your safety. Once the consultation is completed, you will be notified that your application has been accepted, you have now 5 days to complete the deposit payment of 1000€.
  • What is your cancellation policy?
    We believe that there should be some flexibility in the ability to cancel as we understand that unforeseen events can unfold, not enabling you to attend, however we would like you to understand that if canceled too close to the event, we might not be able to fill your spot. Full price paid after your consultation with our physician Processing fee of 100 € (this is non refundable) Deposit: 1000€ Cancellation up to 14 days before the retreat: refund of 50% of what remains after processing fee (ie. 1000€ - 100€ (processing fee) = 900€ * 0.5 = 450€; Your refund would be of 450€) Cancellation up to 7 days before the retreat: no refund
  • Is it possible to arrange a private retreat?
    Yes we have the ability to arrange private retreats. These are suitable for either single individuals or a group of people that already know each other and would like to have a retreat dedicated to only them. Contact us for arranging a private retreat.
  • Which airport is the closest one to the retreat? Which one should I choose?
    The closest airport is Schiphol Airport in Amsterdam.
  • How do I get to the retreat from the airport?
    By car: address is: Vuursesteeg 1, 3749 AN Lage Vuursche, Netherlands. Click here for an up-to-date route planner. By public transport: at railway station Hilversum or Den Dolder, take a taxi or bus 59 (once an hour, not on Sundays) or rent a bicycle. For more information about Dutch public transport, go to (destination: bus stop Venwoude). By Taxi We recommend the following taxi company, with discounts included for our guests. TAXI LAANSTRA +31 6 55 37 12 03 Whether you’re traveling by car or public transport, allow a generous amount of time for your trip so you can arrive on time. Your questions regarding transportation to the center may be directed to us:
  • What are the recommended arrival and departure times?
    Arrival We recommend everyone to be at our premises by no later than 3pm on the first day of the retreat program. Departure You have the choice of leaving on the 4th day of the program from late afternoon onward, or to stay for a 4th night and leave the following morning. Our staff will be helping you to arrange transport should you need any assistance.
  • What are the COVID restrictions for traveling to the Netherlands?
    There are no rules for entering the Netherlands if you: live in an EU/Schengen country; live in a country participating in the EU travel rules scheme. This also applies if you are traveling from a country outside the EU/Schengen area. If you fall into one of these categories: you do not have to fill in a health declaration to enter the Netherlands; you do not have to get tested before departure; you do not have to self-quarantine on arrival in the Netherlands. Tourists and foreign travelers from countries inside the European Union/Schengen area can travel to the Netherlands. An EU entry ban is in effect for people from countries outside the European Union/Schengen area. There are exemptions to the entry ban. Travelers from inside and outside the European Union/Schengen area have to check what documents they need before they travel to the Netherlands. You may find out more information on the following websites ( with updated national guidelines for the Netherlands Additional rules may apply in your destination country, for example testing or isolating upon entry. View the up-to-date corona rules per country (link to on Should you have any doubts or questions, you can always reach out to us and we will be happy to guide you further to the best of our abilities with regards to matters relating to COVID-19.
  • What COVID measures are in place for the retreat?
    We are pleased to inform that as of 23 March 2022, almost all corona restrictions were lifted. To keep the infection rate within bounds, the basic measures remain. Such as: Wash your hands often. Sneeze and cough into your elbow. If you are experiencing any symptoms (cough, fever, sore throat amongst others), stay at home and take a self-test. Testing for Access (1G) no longer required at events Visitors no longer have to show a negative test result. Testing for Access (1G) is not required anymore at any event, large or small.
  • References
    1. Ray TS. Psychedelics and the human receptorome. PLoS One. 2010;5(2):e9019. doi:10.1371/journal.pone.0009019 2. Kometer M, Schmidt A, Jancke L, Vollenweider FX. Activation of Serotonin 2A Receptors Underlies the Psilocybin-Induced Effects on Oscillations, N170 Visual-Evoked Potentials, and Visual Hallucinations. J Neurosci. 2013;33(25):10544-10551. doi:10.1523/JNEUROSCI.3007-12.2013 3. Carhart-Harris R, Nutt D. Serotonin and brain function: a tale of two receptors. J Psychopharmacol (Oxf). 2017;31(9):1091-1120. doi:10.1177/0269881117725915 4. Shao LX, Liao C, Gregg I, et al. Psilocybin induces rapid and persistent growth of dendritic spines in frontal cortex in vivo. Neuron. 2021;109(16):2535-2544.e4. doi:10.1016/j.neuron.2021.06.008 5. Tagliazucchi E, Carhart-Harris R, Leech R, Nutt D, Chialvo DR. Enhanced repertoire of brain dynamical states during the psychedelic experience. Hum Brain Mapp. 2014;35(11):5442-5456. doi:10.1002/hbm.22562 6. Demirtaş M, Tornador C, Falcón C, et al. Dynamic functional connectivity reveals altered variability in functional connectivity among patients with major depressive disorder. Hum Brain Mapp. 2016;37(8):2918-2930. doi:10.1002/hbm.23215 7. Meiran N, Diamond GM, Toder D, Nemets B. Cognitive rigidity in unipolar depression and obsessive compulsive disorder: Examination of task switching, Stroop, working memory updating and post-conflict adaptation. Psychiatry Res. 2011;185(1-2):149-156. doi:10.1016/j.psychres.2010.04.044 8. Krebs TS, Johansen PØ. Lysergic acid diethylamide (LSD) for alcoholism: meta-analysis of randomized controlled trials. J Psychopharmacol (Oxf). 2012;26(7):994-1002. doi:10.1177/0269881112439253 9. Rucker JJ, Jelen LA, Flynn S, Frowde KD, Young AH. Psychedelics in the treatment of unipolar mood disorders: a systematic review. J Psychopharmacol (Oxf). 2016;30(12):1220-1229. doi:10.1177/0269881116679368 10.

We are running holistic psilocybin retreats in the Netherlands. Welcome to our FAQ.

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