Hallo,
Indeed it is interesting stuff !

Really we should not expect any problems if one practices qigong.

But if one has more serious health problems, one might need a good practitioner to speed up things. I have perceived that even best practitioners would have amazing results ( miracles) on some patients, and absolutely no result on some other patients. Some problems are simply not easy to treat.

I have discussed Reiki, because many people have told me their experience with it. Sometimes interesting things happen. One women had breast cancer. She received Reiki, the cancer was gone, but she started to have hallucinations. I do not know what happened later, was she cured from that also or not. But it seems that there was a shift in energy, or some energetic infiltration.

It seems that some people have problems after reiki, whatever the reason. Maybe the changes caused by Reiki can bring the person out of balance ? It seems that people that have tendency to be unstable tend to have such reactions . Also there may be some relationship problem between client and practitioner ? This all can happen with other methods also, it is not specific for Reiki.

I also know of many cures with Reiki !!

I have mentioned the SN Lazarev ( famous healer) and I do recommend his books , but it seems that for some people those books are too radical ( he states that a person should not be too attached to worldy things and values, and that relationships between people should be based on divine feelings, not so much on wordly issues and emotions ) . Love is most important for him, and abandoning the person you love to go with the guy that is rich might cause health problems in the whole family line ( children, grandchildren...) . So if a child is sick it might be that grandmother was not following her heart. It is a different way to look at disease, but it is quite in line with modern psychology.
Many readers report changes and healings from reading his books.

The world of healing is as complex ( or as simple) as life itself, but love is certainly the master healer !