Why do you want to take them? Need a little more info. I have taken both and I'm still here to tell the tale.

Drinking too much water can be dangerous lol so anything in excess can be dangerous. I've worked in a health food store for 11 years and have sold many bottles of each, I also live in Canada and we have very strict regulations about what can and cannot be sold here. If there were serious side effects it would not be sold here. Anyone can have allergies to herbs, everyone is different, but generally both are very safe.