I wouldn't use it during flower as the neem needs to be in the plant before that happens. I believe it is safe to be inside the plant and smoke it. I would say the jury is out on whether or not it is safe to smoke. There needs to be more studies I think. It is listed as a legal pesticide, miticide, fungicide and antimicrobial for California commercial growing. I don't grow for anybody but myself, so if I am doing harm, it's only on me; but I imagine a lot of commercial growers use neem since it is natural and very effective. It is a must for my outdoor grow.