We used revolution too and never had any problems
What I like about it is that they have different doses for different sizes. Some of the others are up to 25lbs, and I do not feel comfortable giving a 3.5 lb or 10lb dog something that's for a dog up to 25lbs. With the revolution they have 0-5lbs, 5-10lbs, and 10-20lbs, and so on.