We use PetArmor now (Walmarts cheapo off-brand of Frontline) but in the XL size, divided into a separate vial and we dose out just the right amount for each pet. I will say though after enduring a flea problem this summer... it SUCKS at "treating" fleas. Since we've been consecutively doing it though; and after spraying our house down with Natural Chemistry's De-Flea Pet & Bedding Spray we have been flea free. And thank goodness... that is a tough battle I'd never do again. For the longest time I said I'd rather just treat fleas as I saw them, to avoid the chemicals... but after realizing just how many flea baths and spraying etc. we had to go through to get RID of them, now I err on the side of caution and just do the low dose of Fipronil. None of my pets have a reaction; and since we've been religious about giving it on time, we've had NO recurrence of fleas. So, while it's pretty poor at getting RID of existing flea problems I do now see the importance of using it as a preventative.