Frontline Top Spot for dogs has always been the product that I've used on my yorkie. It's what my vet applied when I first adopted my puppy and it's what we've stuck with because it's always worked. I've never seen a single flea on my dog and that's very important to me because my dog only goes outside to use the bathroom other than when we go for visits to the park. And my cats are indoor only. So my yorkie is the only one that could bring fleas in the house unless of course one unlikely hitches a ride indoors on the leg of my pants. I also flea treat my cats with a cat spot treatment to make sure everyone remains flea-free. I am very allergic to flea bites myself so our home must remain free of fleas at all times. I'm afraid my kiddos may have inherited my flea allergy and our pets like to share our beds. Quality of Ingredients The quality of ingredients is very high. It kills fleas safely and effectively. Side Effects My yorkie has never experienced a single side effect from using Frontline and hasn't had a single flea.