I don't know where you live, but in my area flea collars are completely ineffective. The topical treatments are little better, but some of them will work for 15 days or so. (not the 30 they're supposed to) So far we've only had any luck with the oral treatments. Fleas are getting very resistant, though it might not be as much of an issue in your area. Your vet should have more locally-relevant advice!