Amazon is already undercutting prices on over-the-counter pills

In midtown Manhattan at a Duane Reade store, part of the Walgreens chain, a store-brand pack of 500 acetaminophen pills costs $18.99. Amazon is selling the same count and strength product for $7.40. Two allergy medications — cetirizine, also known as Zyrtec, and loratadine, sold under the Claritin brand — cost about three-quarters less on Amazon than the drugstore chains’ house brands did in the store.