Hydrogen water pills are a form of effervescent supplement designed to change ordinary drinking tap water into hydrogen-enriched water. When slipped into water, these pills react—usually by way of a magnesium and acid reaction—to create contained molecular hydrogen fuel (H₂), which doesn't usually stay in water for long on their own. The end result is water with larger degrees of contained molecular hydrogen that enthusiasts and some scientists feel will help help the body's antioxidant defenses. best hydrogen water tablets