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.
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.
The 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.
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. 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.
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. The key is informed practice — understanding that mindfulness is a skill that requires appropriate instruction, gradual progression, and self-compassion. 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.