Very Very Safe
At present, most of the means to treat diseases such as drugs, surgery and so on almost have different bad effects on the human body. Many drugs, for example, for high blood pressure, diabetes and so on, are taken for life. The most common side effect of drugs is to treat a disease in one organ and impair the function of another. But hydrogen is very different. It has no adverse effects on humans, and there has never been a case in the last 200 years that hydrogen has had a negative effect on humans.
