I normally take some chinese herbal viagra (sildenafil) befor doing sex and they work. But I afraid that these tablets may have side affecting. Please would you kind?

HERBS. There is no such animal as herbal viagra (sildenafil). One is a synthesized compound and the other is a plant. Use what works best for you and carefully research the side effect profile and the warnings on the labels.
Depends. It is impossible to say without knowing what is in the "herbal viagra".
More info needed. Please resubmit your question with the specific name of the chinese herb so we can provide an informed response. If there is a list of ingredients, please include that.