Previously I posted an article called "Practitioners be warned" referring to a study by a psychiatrist in Shanghai discussing and documenting some severe cases of chi-kung practice went wrong. Recently I read a Chinese book "The foundation practice of Dacheng Kungfu"(大成拳築基功) by a famous chi-kung teacher in China, madam Mei Jingke 祕靜克. Master Mei now aged 97 is still actively teaching the practice of Zhan Zhuang for sick, weak and convalescent people. She was a student of the late grandmaster Wang XianZhai 王薌齋, and has been focusing her teaching for health benefits rather than as martial art. I was in for a pleasant surprise when I noticed that there is one chapter titled as "Prevention and curing of side-effects".
On the hand there are people who are too impatient to be benefited from chi-kung, and on the other hand there are people who put in a lot of effort but getting side-effects. Oftentimes, teachers and fellow practitioners are too eager to promote the practice without proper advice on possible side-effects. And I can see there are folks on the web (including blogs and discussion forums) saying that one can experiment in whatever way without any side-effect! So, practitioners be warned!
Fortunately, the majority of the side-effects are not psychotic cases (unless one with psychotic tendency, and thus should be seriously warned), but just chi being trapped in somewhere, oftentimes inside the head. According to the Master, such trapped chi, most often, can go away by itself after a few years even without any attention. Most of her curing method involves massage at the affected area. My opinion is that with the personal guidance of a chi-kung teacher, and assuming one is proficient with chi at certain level, chi can be directed away from the affected area without much difficulty. If the affected areas are quite general, some jogging or hiking are recommended.
How to avoid? The first line of defense is to practice zhan zhuang, in addition to whatever chi-kung one is practicing. In particular, during your zhan zhuang practice, put emphasis on building the strongest chi-points at your stretched hands. The reason is that after a practice session, when the strongest points are relaxed, chi will be directed to these points and can be dissipated accordingly.
Would you be deterred by such possible side-effect? I hope not!
PS: Another point I find interesting on Master Mei's book is that she considered Taoist yoga as forerunner of her zhan zhunag practice. I believe any practitioner of chi-kung can benefit from study of the classic practice of Taoist yoga (i.e. re-inventing and re-interpreting Taoist yoga as a living practice, in short, demystify this classic practice).