What the Research Says About Adverse Effects
A groundbreaking 2020 study published in Acta Psychiatrica Scandinavica by Marco Schlosser and colleagues at University College London surveyed over 1,200 regular meditators and found that approximately 25 percent reported experiencing at least one adverse effect, such as increased anxiety, disturbing thoughts, or altered perception. However, the severity varied widely -- most adverse effects were mild and transient, while serious effects were rare. A separate 2022 systematic review in Clinical Psychology Review by Willoughby Britton at Brown University examined 83 studies and concluded that while adverse effects do occur, they are typically short-lived and most commonly affect individuals with pre-existing mental health conditions or those engaged in intensive retreat-style practice rather than moderate daily sessions. It is important to contextualize these numbers: a 25 percent rate of any adverse effect (including mild and temporary experiences) is comparable to the adverse effect rates reported for most evidence-based psychological therapies, including cognitive behavioral therapy. A 2019 study in Psychotherapy and Psychosomatics found that approximately 43 percent of psychotherapy clients report at least one unwanted event during treatment, suggesting mindfulness is no more risky than talking therapy. The most comprehensive study of meditation-related adverse effects to date, the "Varieties of Contemplative Experience" project led by Dr. Britton at Brown, has catalogued a wide range of experiences across thousands of practitioners and concluded that the vast majority of challenging experiences are temporary, manageable, and ultimately integrated into ongoing practice without lasting harm.
Types of Adverse Experiences Reported
The adverse experiences associated with mindfulness practice fall into several categories, and understanding them helps practitioners distinguish between normal challenges and genuine warning signs. Cognitive effects include racing thoughts, intrusive or disturbing thoughts, and difficulty concentrating after practice. Perceptual effects can include heightened sensory sensitivity, changes in the perception of time, or occasionally experiences of derealization -- a feeling that one's surroundings seem unreal. Affective effects encompass increased anxiety, fear, sadness, or emotional volatility, particularly when suppressed emotions surface during practice. Somatic effects include unusual physical sensations such as tingling, pressure, temperature changes, or involuntary movements. Social effects may involve a sense of detachment from others or difficulty engaging in everyday social interactions. In the Schlosser study, the most commonly reported adverse effects were anxiety (reported by 33 percent of those who had any adverse effect), followed by disturbing thoughts (25 percent) and altered perception (22 percent). Dr. Jared Lindahl, a researcher at Brown University who co-leads the Varieties of Contemplative Experience project, notes that many of these experiences have been well-documented in contemplative literature for centuries under names like "dark night of the soul" or "kundalini awakening," and that traditional meditation systems typically included teacher guidance specifically designed to navigate them. The challenge in modern secular mindfulness is that many practitioners lack access to experienced teachers who can help contextualize and navigate these experiences when they arise.
Who May Be at Greater Risk
Certain populations should approach mindfulness with additional care and professional guidance. People with a history of trauma, particularly complex PTSD, may find that sustained body awareness or silent meditation triggers trauma responses such as flashbacks or dissociation. Dr. David Treleaven, author of "Trauma-Sensitive Mindfulness," emphasizes that traditional mindfulness instructions to "stay with difficult sensations" can be retraumatizing for some individuals. People experiencing active psychosis or severe dissociative disorders may find that meditation amplifies symptoms rather than alleviating them. Additionally, individuals with a history of depersonalization or derealization should proceed cautiously, as intensive meditation can sometimes exacerbate these experiences. This does not mean mindfulness is off-limits for these groups -- rather, it means a trauma-informed approach with qualified guidance is essential. A 2021 study in Mindfulness journal by Nicholas Van Dam and colleagues found that the strongest predictor of adverse meditation experiences was the intensity and duration of practice: participants on intensive silent retreats were significantly more likely to report adverse effects than those engaged in moderate daily practice. People with bipolar disorder should be particularly cautious during manic episodes, as the heightened awareness cultivated by mindfulness can sometimes intensify the rapid cycling of thoughts and emotions characteristic of mania. Individuals currently in acute psychological crisis -- severe suicidal ideation, active psychotic episodes, or acute dissociative states -- should generally stabilize with conventional treatment before adding mindfulness to their approach. The key takeaway is not that these groups should avoid mindfulness altogether, but that they benefit from working with teachers or therapists who understand their specific vulnerabilities and can adapt practices accordingly.
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Get Started FreeThe Difference Between Discomfort and Harm
An important distinction exists between the natural discomfort that arises during mindfulness practice and genuine harm. Mindfulness often involves sitting with difficult emotions, uncomfortable physical sensations, or challenging thoughts -- this is not a side effect but a core feature of the practice. Jon Kabat-Zinn himself has noted that MBSR participants frequently experience temporary increases in awareness of stress and pain before experiencing reduction. This initial discomfort is a sign that the practice is working, much like physical soreness after starting an exercise program. Genuine adverse effects, by contrast, involve symptoms that are qualitatively different from what you brought to the practice -- such as new-onset panic attacks, persistent dissociation, or a worsening of pre-existing conditions that does not resolve after a session ends. Dr. Willoughby Britton offers a useful framework for distinguishing between the two: transient discomfort that resolves within hours and leaves you with greater clarity or equanimity is typically a normal part of the practice process. Persistent symptoms that worsen over days or weeks, that you have never experienced before, or that significantly interfere with daily functioning are signs that you should modify your practice or seek professional support. Another helpful marker is whether the experience occurs within your "window of tolerance" -- the zone between being overwhelmed and being shut down. Mild emotional activation during practice that you can observe and stay with is productive discomfort. Activation that tips you into panic, dissociation, or emotional flooding exceeds your window of tolerance and signals a need to modify the intensity of your practice. Understanding this distinction empowers practitioners to work skillfully with the inevitable challenges of mindfulness rather than either pushing through harmful experiences or abandoning the practice at the first sign of difficulty.
The Role of Intensity and Setting
Research consistently shows that the risk of adverse effects is closely related to the intensity, duration, and setting of mindfulness practice. Moderate daily practice of 10 to 30 minutes carries very low risk for most practitioners. In contrast, intensive silent meditation retreats -- where practitioners may meditate for 10 or more hours per day over periods of several days to several weeks -- represent a significantly higher risk context. A 2017 study by Lindahl and colleagues published in PLOS ONE examined 60 practitioners who had experienced meditation-related difficulties and found that 73 percent of the challenging experiences occurred during or after intensive retreat practice. The lack of external stimulation, extended periods of introspection, sleep disruption, and the absence of normal social interaction during retreats can create conditions where suppressed psychological material surfaces rapidly, sometimes faster than a practitioner can integrate it. Dr. Jack Kornfield, a clinical psychologist and renowned meditation teacher, estimates that roughly one in 20 intensive retreat participants experiences a psychological crisis significant enough to require intervention. He advocates for retreats to have mental health professionals available on-site and for screening processes that identify high-risk participants. Even outside retreat settings, longer individual sessions can occasionally trigger unwelcome experiences, particularly for people new to the practice. The general guideline from MBSR is to build practice duration gradually, starting with 10 to 15 minutes and increasing over weeks, allowing the nervous system to adapt to the increased self-awareness that mindfulness cultivates. This graduated approach significantly reduces the likelihood of being overwhelmed by difficult material surfacing too quickly.
Trauma-Sensitive Mindfulness: Adapting Practice for Safety
Trauma-sensitive mindfulness is an approach that modifies traditional mindfulness instructions to be safer for people with trauma histories. Developed by practitioners including Dr. David Treleaven, Dr. Bessel van der Kolk, and the team at the Trauma Center at Justice Resource Institute, this approach recognizes that certain standard mindfulness instructions -- such as closing the eyes, sitting still, or focusing intensely on body sensations -- can inadvertently trigger trauma responses in some individuals. Key modifications include offering the choice to keep eyes open or closed (rather than defaulting to closed eyes), providing movement options alongside seated stillness, using language of invitation rather than instruction ("you might notice" rather than "focus your attention on"), avoiding prolonged silence that may feel threatening, and actively encouraging practitioners to shift their attention to neutral or pleasant anchors if body awareness becomes distressing. Van der Kolk's groundbreaking book "The Body Keeps the Score" details how trauma is stored in the body and how mindful, gradual body awareness -- when approached with safety and choice -- can be a powerful path to healing. A 2014 randomized controlled trial by van der Kolk and colleagues, published in the Journal of Clinical Psychiatry, found that trauma-sensitive yoga (which incorporates mindfulness principles) significantly reduced PTSD symptoms in women with treatment-resistant PTSD. The key principle across all trauma-sensitive approaches is that the practitioner maintains agency and choice throughout the practice, never feeling trapped, forced, or unable to modify their experience. This principle of empowered choice is actually beneficial for all practitioners, not just those with trauma histories, and represents best practice for any guided mindfulness session.
The McMindfulness Critique and Ethical Considerations
Beyond individual adverse effects, critics have raised broader concerns about the way mindfulness has been commercialized and deployed in Western contexts. The term "McMindfulness," coined by Professor Ronald Purser of San Francisco State University and popularized in his 2019 book of the same name, critiques the reduction of mindfulness to a corporate productivity tool stripped of its ethical foundations. In traditional Buddhist contexts, mindfulness was always embedded within a broader framework of ethical conduct, compassion, and wisdom. Critics argue that when mindfulness is used to help soldiers fight more effectively, to make overworked employees more productive without addressing systemic workplace issues, or to help consumers feel calm while ignoring societal problems, it has been divorced from its transformative potential and co-opted to serve existing power structures. Dr. Bhikkhu Bodhi, a respected Buddhist scholar and monk, has cautioned that "absent a sharp social critique, Buddhist practices could easily be used to justify and stabilize the status quo." While these critiques do not negate the genuine personal benefits of mindfulness practice, they raise important questions about how mindfulness is taught and framed. A more complete approach to mindfulness includes not only attention training and stress reduction but also the cultivation of compassion, ethical awareness, and a sense of connection to something larger than individual wellbeing. Research by Dr. Paul Condon at Southern Oregon University found that mindfulness training that includes an explicit ethical component -- such as loving-kindness meditation or compassion practices -- produces greater prosocial behavior than attention-focused mindfulness alone, supporting the argument that the ethical dimensions of mindfulness are not optional extras but essential components of effective practice.
How to Practice Mindfulness Safely
Safe mindfulness practice starts with appropriate instruction and self-awareness. Begin with shorter sessions of five to ten minutes rather than jumping into hour-long sits or multi-day retreats. Choose guided practices over unguided ones when starting out, as a teacher's voice provides grounding and structure. If you have a history of trauma or mental health conditions, look for trauma-sensitive mindfulness programs and work with a qualified instructor. Pay attention to your window of tolerance -- if a practice consistently leaves you feeling worse rather than better, modify the technique or try a different approach such as walking meditation or mindful movement instead of seated silence. Here are specific safety guidelines drawn from the clinical mindfulness literature: First, never increase practice duration by more than five minutes per week to allow gradual adaptation. Second, keep your eyes partially open during meditation if closing them feels uncomfortable or disorienting. Third, always have a grounding anchor available -- physical touch of a chair, feet on the floor, or holding a small object -- that you can return to if emotional intensity becomes overwhelming. Fourth, do not practice when acutely distressed; instead, use active coping strategies like walking, talking to someone, or calling a crisis line, and return to mindfulness when you are within your window of tolerance. Fifth, if you experience persistent symptoms lasting more than a few hours after practice -- such as dissociation, panic, or intense emotional disturbance -- stop the practice and consult a mental health professional familiar with meditation-related experiences. The Selfpause app provides gentle, guided mindfulness sessions with built-in grounding techniques, offering a safe on-ramp for beginners and those who prefer a structured approach with the added comfort of voice-guided instruction.
When to Seek Professional Support
Knowing when to seek professional help is an important aspect of responsible mindfulness practice. If you experience any of the following after beginning or intensifying a mindfulness practice, consider consulting a mental health professional who is knowledgeable about contemplative practices: persistent feelings of unreality or detachment from yourself or your surroundings lasting more than a few hours; significant worsening of pre-existing mental health symptoms; new-onset panic attacks or intense fear responses that were not present before practice; intrusive thoughts or images that feel uncontrollable and distressing; a marked increase in suicidal ideation; or episodes of dissociation where you lose track of time or feel disconnected from your body. Finding a therapist who understands both mindfulness and mental health is important, because a therapist unfamiliar with meditation may pathologize normal meditation experiences, while a meditation teacher without clinical training may fail to recognize genuine psychological distress. The Cheetah House project at Brown University, founded by Dr. Willoughby Britton, specifically provides support for people experiencing meditation-related difficulties and maintains a referral network of clinicians trained in both contemplative practice and clinical psychology. Organizations like the British Association for Counselling and Psychotherapy and the American Psychological Association now include mindfulness competencies in their training guidelines, making it easier to find qualified professionals. Remember that seeking help is not a sign of failure but a sign of wisdom -- the Buddha himself emphasized the importance of working with a skilled teacher, and modern clinical mindfulness programs were always designed to be delivered by trained professionals rather than practiced in isolation.
The Bottom Line: Benefits Far Outweigh the Risks
Despite the nuances outlined above, the overwhelming weight of evidence supports mindfulness as a beneficial practice for most people. A 2014 meta-analysis by Goyal and colleagues published in JAMA Internal Medicine, examining 47 randomized controlled trials with over 3,500 participants, found moderate evidence that mindfulness meditation reduces anxiety, depression, and pain. A subsequent 2019 meta-analysis by Goldberg and colleagues, examining 142 trials with over 12,000 participants, confirmed and extended these findings across a broader range of outcomes. The key is informed practice -- understanding that mindfulness is a skill that requires appropriate instruction, gradual progression, and self-compassion. The risks are real but manageable: practice at moderate intensity, use guided instruction, start gradually, and seek professional support if needed. Most adverse effects are temporary, mild, and resolvable with simple modifications to one's practice approach. For context, the adverse effect profile of mindfulness is considerably more favorable than that of most pharmaceutical interventions for the same conditions. No one has ever died from mindfulness meditation, while pharmaceutical side effects cause tens of thousands of emergency room visits annually. The risk of doing nothing -- of leaving stress, anxiety, and depression unaddressed -- almost certainly exceeds the small risks of responsible mindfulness practice. If you experience persistent negative effects, consult a mental health professional who is knowledgeable about contemplative practices. For the vast majority of practitioners, mindfulness remains one of the safest, most accessible, and most well-researched approaches to improving mental health and wellbeing.