I bought Frontline Plus for adult cats at Sam's. After the first application there was no noticeable improvement, we actually started seeing flea eggs where Fred sleeps.
Even though the packing leads you to believe it's effective for a month = "Monthly Treatment" I tried another application two weeks later, thinking perhaps I did the first application incorrectly. I looked up Applying Flea Control Medication on YouTube and did exactly as instructed. Nothing. The poor guy is still itching, licking, itching, licking.
I believe the active ingredient in Frontline is either no longer effective, fleas are immune. Might be more effective squirting on actual Snake Oil than Frontline.
Review about: Merial Flea Control.
Monetary Loss: $45.