Yes it does have warnings on the container. It reacts with acids so some people may have a slight reaction on their skin if their skin is very acidic and wet. I get it on my skin all the time and it does not bother me at all. I would suggest not getting it in your eyes or inhale any of it. You would not want a reaction taking place in those types of body areas.
Remember you are only using a tablespoon mixed in a whole gallon of water. It's very safe to touch or drink mixed within the drink.
I'm so sorry you are having to deal with fear about it.