AIO about MIL gave 4 month old drugs while babysitting

Mother in law gave our 4 month old drugs without consulting us before, or telling us after. My partner thinks that this is "homeopathic" and natural and therefore has no potentially for harm. That shouldn't even matter - don't put anything in my kids body without my consent. Like I understand them sneaking a candy when he is older but this is a massive overstep to me. AIO? I don't know enough to have an educated opinion on the efficacy, but how does MIL know if this interacts with something else we may or may not have given him that day? We aren't doctors, but neither is she.

Shouldn't we be consulted before putting something in his body. My partner isn't concerned about the safety side of it, but does agree with me that this is an overreach on her part. I'm over here thinking just because it's natural doesn't mean it's healthy. Like... bears are natural too and I wouldn't invite one into my house.