About this item 8 months (4 doses) flea treatment and prevention for indoor and outdoor cats or kittens 1.8-9 lbs., 8 weeks or older Longer-lasting protection vs. other topical products; 2 months protection per dose, outlasting the typical flea life cycle Fast-acting treatment starts killing fleas through contact within 30 minutes to 4 hours Easy-to-apply topical treatment, no prescription needed Fragrance-free formula, containing a naturally derived ingredient Spinetoram – winner of a Green Chemistry award* *US EPA Presidential Green Chemistry Challenge. Designing Greener Chemicals Award. 2008.