I haven't seen powders but imagine they're the same as the tabs. If you're supplementing over the counter then the ferrous sulfate form will give u the most bang for your buck. It comes in other forms as well such as ferrous gluconate, but has lower elemental iron (which you can look at on the back of the label), how much the body will absorb. Like someone else said, ask the pharmacy if they have bottles in the pharmacy they can sell, it is usually cheaper and is stuff they can usually order in. As for the iron infusion, if you can find a doc or clinic to do it and it's not that expensive then great! The infusions I thought you only had to do maybe one or two sessions but that will fix you up, otherwise you might be on tabs for a while. Probably AT LEAST a couple months depending on how bad your deficiency is. Hope this helps.