Background: Research on the adverse effects of mindfulness-based programs (MBPs) has been sparse and hindered by methodological imprecision.
Methods: The 44-item Meditation Experiences Interview (MedEx-I) was used by an independent assessor to measure meditation-related side effects (MRSE) following three variants of an 8-week program of mindfulness-based cognitive therapy (n = 96). Each item was queried for occurrence, causal link to mindfulness meditation practice, duration, valence, and impact on functioning.
Results: Eighty-three percent of the MBP sample reported at least one MRSE. Meditation-related adverse effects (MRAEs) with negative valences or negative impacts on functioning occurred in 58% and 37% of the sample, respectively. Lasting bad effects occurred in 6-14% of the sample and were associated with signs of dysregulated arousal (hyperarousal and dissociation).
Conclusion: Meditation practice in MBPs is associated with transient distress and negative impacts at similar rates to other psychological treatments.
Keywords: adverse effects; harms monitoring; meditation; mindfulness.