When our beloved dog was with us, he... well had sensitive skin, and the drops irritated his skin, as well the over the counter chews did not work on him and made him sick... We had to give him the pills...
When we traveled with our a dog, Even with using the pills, I had a spray product that I would spray him down with before getting back into the Truck, so that if there were any fleas at the rest areas, or wherever we stopped, to let him go potty, a flea might jump on him and get in the truck... I would just spray him, then wipe it all over with a towel, then use another towel to dry him off with. I used old towels, cutting them up into small squares he was a chihuahua, and just bagged them and threw them away at the rest areas ... I got this product at the vets office, due to sensitive skin...
I do think that you can get a product over the counter, at Petsmarts or maybe in a feed store it kills fleas and ticks.
Our friends have 2 dogs and a motor home they use a over the counter chew-able, and it works for them... plus they get a bath weekly - with a product for fleas and tick's. When they travel and they use an over the counter spray-able product... every-time they start back get in the RV... and works really well... It cost them 1,500 bucks to get the RV treated, when some rouge fleas got on their babies and hitched a ride and got inside the RV and they set up housekeeping... So now they get sprayed and brushed down, and dried off before getting back into the RV... she said its a pain, but better then forking out 1,500 dollars, and the dang fleas eating them up...
As well you can have have your yard sprayed for flea's, which will help cut down on the possibility of flea's getting in the house... doing a flea treatment to for the inside of the house can get really pricey really fast.