Okay, a whole herb that is water extracted is okay, (what you want to avoid is when they extract only one or two chemical compounds from the entire plant) but one thing that would be problematic is getting the proper dosage because we don't know exactly what the potency is. Like you said, stopping for a few days and then maybe start again at a lower dose, or buying a whole herb will give you a better idea of the dosage. A typical dosage is 2-3 500 mg tablets of ashwagandha (not extract, just the whole plant in tablet form). If you are taking it in powder form, the dosage is usually higher, 1/2-1 tsp. per day, around 2.5-5 grams, but it all depends on the person. You always want to start with the lowest dose that you have noticeable beneficial effects.