Yes. Hydrogen gas has been shown to be very safe at concentrations hundreds of times higher than what is being used for therapy. Here are a few examples:
Hydrogen’s safety was first shown in the late 1800s, where hydrogen gas was used to locate gunshot wounds in the intestines. The reports showed that there were never any toxic effects or irritation to even the most sensitive tissues. Furthermore, hydrogen gas is natural to the body because after a fiber-rich meal, our gut bacteria can produce liters of hydrogen on a daily basis (which is yet another benefit from eating fruits and vegetables).In short, hydrogen gas is very natural to our bodies, not like a foreign or alien substance that can only be synthesized in a chemistry lab.