I've been taking it a while. At first it was working real well and I don't know if my body just got used to it or what but after a while it seemed to have stopped. On the box it states it's good for both "C" and "D" and in the first few days you may experience gas/bloating which is normal. Also, if you're menstruating or sick, they suggest you increase the dosage during that time. Heidi