Treat flea infestations on dogs and puppies four weeks of age and older. Safe for pregnant or nursing dogs as well. Begins working within 30 minutes and kills more than 90% of adult fleas within 4 hours. Use when pets are likely to be exposed to fleas, such as in dog parks, at shows, or other areas. Safe to give as often as once daily if re-infestation occurs. 6 tablets per package. Small: 2-25 lb Large: 26-125 lb