Amazon has launched a pharmacy business, offering to fill prescriptions for delivery by mail.

The retail giant barging in — its biggest foray into health care yet — reverberated through the industry on Tuesday. Shares of CVS were down about 8% at midday, while Walgreens tumbled 9% and Rite Aid 15%.

Prescription drugs are an industry worth hundreds of billions of dollars — and more people have turned to ordering medications by mail during the coronavirus pandemic. Analysts say Amazon's move could particularly affect smaller drugstores.

Amazon has eyed this market for a while, also pushing to compete with big-box stores such as Walmart and major pharmacy chains that have long offered home delivery, in some cases same-day. In 2018, Amazon acquired online pharmacy PillPack, which mainly focuses on people who take multiple medications a day.

Now the retailer says its shoppers can order generic and name-brand drugs for delivery within days. That includes common prescriptions such as insulin, inhalers and blood pressure medications. The company says it will not deliver most opioids, which are controlled substances.

Amazon has launched the service for now in 45 states, excluding Hawaii, Illinois, Kentucky, Louisiana and Minnesota. Amazon Pharmacy promises free two-day delivery for members of the company's Prime subscription, which costs $119 a year in the United States.

The retailer says its pharmacy will accept most insurance. But it's also promoting its own discount program for paying subscribers, which Amazon says will apply not only to its marketplace but also at 50,000 other pharmacies nationwide.

Editor's note:Amazon, CVS and Walgreens are among NPR's recent financial supporters.

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