I agree with JenBKR; the medications you can get without a prescription tend to be much less effective. I get my prescriptions from the vet and then use 1800PetMeds (both the phone # and the website, depending on what mood I'm in ), for a less expensive alternative to buying directly from the vet. It's really easy, and I receive my stuff within a week for most things (vaccines are overnight-shipped on an ice-pack).