Every tick & flea medication has some risk. Those applications which you apply monthly are pesticides. Those pesticides work on the nervous system to kill ticks and fleas. Some animals have had adverse effects including seizures. There are no real government regulations on these products as can be seen on the packaging which they don't list the inactive ingredients.

Fortuneately, my dog does well with Frontline Plus but not Advantage. There is a new product on the market PetArmor. Several board of directors were former Frontline directors so they copied the formula from Frontline and was promptly sued. But its available at Walmart and Sam's Club.