Is Frontline safe for my puppy??

Hello to all of you. Last week we were notified through a friend that there was a male puppy that desperately needed a home. We went there to look and devestated by the place where he had been raised. no grass, no yard, only lived in a large hole that the parentsd had dug. MY husband could not wait to get him out of therre fast enough. well, it gets better. On the way home noticed he was covered with fleas and ticks. We did not bring him in the house right away and gave him a over the counter fleas shampoo outside. Took him to the vet the next day and got another bath there. Sorry , this is so drawn out. The vet recommended him to be on Frontline starting Saturday. Is this safe for hom He is 12 weeks old and weighs 26 lbs. We just lost our beautiful boy Cody also a german shepherd and so paranoid we will do something to hurt this little one. He is adorable and craves attention and just plays like a little maniac. Loves to be cuddled and on my heels whereever I go. Is frontline safe for him. ? Please please respond.