We had tried several brands of spot on type flea control, sprays, shampoos, collars, you name it, for our miniature schnauzer and yorkie who had suffered severely from fleas since moving to Florida this summer. We sprayed our yard with the strongest thing available. Even fighting diligently with these products and hand picking and killing, the fleas continued and were starting to get in our house, every time they went out the fleas came back in and nothing was working. Even though it is more expensive than those other products, we figured we would give comfortis a try. We had already spent a lot over time to no avail. You get what you pay for! Within an hour of taking, fleas were dying and within a day, they were virtually eliminated. This is amazing, I sure hope it keeps working this good. Some have mentioned their dog vomiting after giving the pill, but I made sure that my dogs ate first and had no problem and they gobbled the pill like a treat.