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Adverses effects. Meditation research site. http://www.researchingmeditation.org/.
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"Reports such as those described previously call for a deeper examination of meditation’s potential adverse effects. Thorough, systematic surveys post marketing surveillance-style studies need to be conducted, For this to be done properly, meditation instructors and organisations may be required to cooperate by providing comprehensive lists of those who have learnt or who currently practice meditation. In practice this may be difficult to achieve given the commercial interests of some organisations, the somewhat anti-establishmentarian views of those who practice in or participate in these organisations as well restrictions arising from privacy laws."

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"When decisions about a new intervention are being made, the net clinical benefit needs to be carefully assessed by balancing reported benefits and side effects. The CONSORT check-list includes reporting of such adverse events as item 19 of the CONSORT statement. Only proper and systematic reporting of side effects will allow adequate assessment of the potential net benefit of any intervention."

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"In light of the number of studies reporting adverse effects from meditation broad based surveys need to be conducted, and given that studies such as Kaldor’s (2002) suggest that up to 10% of the population may have tried meditation at some time, a direct-to-public cross sectional survey may be sufficiently effective in quantifying adverse effect rates. Also important are controlled observational studies with a specific focus on detecting, characterising and quantifying adverse reactions. Moreover, meditation should not be the only modality assessed but instead, the opportunity should be taken to assess the effects of all related quasi therapeutic practices including hypnosis, faith healing and Qigong, Reiki and other new age practices. Combining the outcomes from these different data gathering strategies on a wide variety of contemplative and new age practices will not only help us understand adverse effects associated with meditation but also provide a perspective with regard to related practices. Such information will hopefully help to explain why a practice traditionally described as beneficial seems to be associated with a consistent reporting rate of adverse events."

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"Two cases are described in a report by Xu (1994). The first involved a 22 year-old man who sought treatment for lumbago and experienced the onset of adverse effects while undertaking self-teaching of the Wu Qin Xi form of Qigong. He experienced anxiety, physical pain, psychosis and suicidal thoughts. Some relief was experienced as a result of treatment by a Qigong master, but symptoms recurred. These included hearing the “voices of evil spirits”, uncontrollable behaviour and attempted suicide. Some months later he developed similar symptoms when his family would not allow him to do his Qigong exercises. He attempted suicide and was admitted to a psychiatric institution. After ECT treatment he was discharged and was subsequently stable. The second case involved a 44 year old male who developed delusional psychosis after practicing He Xiang Zhuang (a form of Qigong) for a cervical disorder."

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"Although many of meditations adverse effects reported in literature are anecdotal cases studies, incidental findings or unexpected outcomes it is clear that meditation is not a universally benign intervention and that it can be associated with both serious and non-serious adverse reactions. Some studies, such as those of Otis (1984) and Persinger (1993, 1992), suggest a dose response relationship whereas others, such as that of Xu (1994), suggest an unpredictable idiosyncratic effect."
"Xu (1994) described and discussed the adverse effects of Qigong, which has been described as both a therapeutic practice as well as the “Chinese equivalent of Indian meditation”. The clinical consequences of inappropriate use of this technique has been described as the “Qigong deviation syndrome”, which has become a diagnostic term “now used widely in China” and is associated with a range of somatic and psychological disturbances. The commonest somatic symptoms include headaches, insomnia and discomfort caused by abdominal distension, while common psychological symptoms include anxiety, agitation and depression. Extreme psychological symptoms can include uncontrollable behaviours, psychosis and suicide."

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"Kennedy (1976) described 2 cases in which de-personalisation appeared to be triggered by meditation. The first case developed after the subject used breathing and meditation exercises described in a book on self-development. The experience continued for at least 16 months. The second case involved the use of meditation techniques recommended by the Arica Institute. While at first pleased with the experiences, the subject soon found he was unable to maintain a job and needed professional help."

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"Shapiro (1992) observed the effects of vipassana meditation on a small group of meditators and found that while most participants experienced positive results, a small number of meditators experienced distinctly negative states."

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"lueck (1984) studied 110 participants and reported that the practice of transcendental meditation (TM) appeared to release repressed subconscious impressions. A small proportion of participants reacted adversely to this experience. Heide (1983, 1984) found that 54% of anxiety prone participants demonstrated increased anxiety during mantra meditation modelled on TM. Otis (1974) observed a cohort of 62 novices who tried TM and concluded that it was not suitable for those with serious emotional problems."

"Lazarus (1976, 1984) described several cases in which psychiatric problems such as depression, agitation and schizophrenic de-compensation were observed. These included a 34 year old woman who became suicidal and a 24 year old woman who experienced severe de-personalisation, apparently as a result of transcendental meditation (TM). He also suggested that participants who failed to experience the benefits of meditation might experience a sense of failure and anxiety rather than the enhanced self-understanding that they perhaps were looking for."

"Traditional meditation texts often warn of the potential negative effects of meditation. These can arise as a result of incorrect preparation, instruction, practice or supervision. Traditionally speaking, misconceptions about the ultimate goals of meditation have often led to unfortunate consequences."