Repeat monthly for 2 - 3 months and stop. Watch for fleas and repeat cycle when necessary. To see fleas in cats, put them on a table over a white paper and rub them all over. Look for the flea droppings that look like commas. When you see commas, use Advantage.
Advantage usually works as the single method of flea control without the house and yard treatment.
Advantage is safe without serious side effects. This is a great time to get a short haircut for the season. Stay out of foxtail areas until late July. Use baby oil to soften the foxtail in the ear and the pain will go away and removal will be easier in the morning. Foxtails in the nose cause intense sneezing.