CVS said it would sell 90-day supplies of numerous drugs for $9.99 and offer discounts for customers paying cash at in-store medical clinics, the Los Angeles Times reported Friday.

Wal-Mart Stores Inc. (NYSE:WMT) fired the first salvo in the drug store price wars, the Times said, and hers have been playing catch up with their prices.

On Friday, rival chain Walgreen said generic discount programs had cut into their sales, the Chicago Sun-Times reported.

"We're not pleased," said Walgreen's President and Chief Operating Officer Greg Wasson.

Many retailers view generic drugs as a loss leader, a low priced item with little or negative profit margins that lures customers into stores, the Times said.

"As soon as you go to the back of the CVS to pick up your prescription or wait for it to be filled, what are you going to do? You are going to shop," said Stephanie Nelson, an Atlanta resident who advises shoppers at Couponmom.com.

In spite of the complaint, Walgreen said its prescription sales rose 3.4 percent in October.