My fiancee (she's been a vet ass't for the last two years) says "When using Frontline Plus you need to only be using that product, you apply it in one spot in between the shoulder blades and allow it to dry for 48 hours, then you can bathe with a mild dog shampoo as needed, dont use any other flea products on the dog or it will strip the frontline and waste your money. All animals in the house need to be treated. Frontline is good for fleas for 2 months, but should still be applied every 30 days in high infested homes. Fleas will die outside after a good couple of frosts hit the ground, but if you have them in your home then you need to treat for about 3-4 months to kill the fleas in that environment. What happens is the medication works its way into the sebacious (oil) glands in the skin, and when your dog sheds, the hair with medication gets into your carpet and kills the fleas and eggs. You can still see live fleas on the dog when using Frontline, but the key is to make sure they are moving slowly which indicates they are dieing. Frontline plus will kill all 4 stages of fleas and 4 species of ticks. However if you bought the product from a company other than your vet hospital then that could be the reason the medication is not working. Other companies are not legally supplied this medication and is stored improperly, which makes the medication ineffective. If you did purchase the medication from your vet and you are still having problems with fleas, then you need to contact them for possible deffective medication sold from the company. Which does happen, oaccassionally we do get bad batches."