I use Bio-K, which is a yogurt-consistency preparation that tastes like buttermilk. All probiotics should be taken with meals, once you already have something in your stomach. If you have them on an empty stomach, your stomach acids will kill almost all of the bacteria, but if you have them with food, only about 95% (!!) will die - but 5% of them is enough to make a difference, and fix you up after antibiotics.