Scott Gottlieb, commissioner of the Food and Drug Administration (FDA) listens during a House Oversight and Investigations Subcommittee hearing in Washington, D.C., March 8, 2018.

Outgoing Food and Drug Administration Commissioner Scott Gottlieb told lawmakers Wednesday that he's uneasy about Walgreens' and CVS' recent decisions to start selling CBD products in their drugstores.

Gottlieb on Tuesday also tweeted "concern" about the change without calling the companies out by name.

"We expressed concern yesterday, I did, about Walgreens and CVS stepping into this market. So you now see big-box stores seeking to market CBD products for some uses where the claims seem to be potentially over the line, for the treatment of pain for example," Gottlieb said Wednesday at a House Appropriations Committee hearing.

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Both Walgreens and CVS last month announced they would introduce CBD-infused topical products like creams and salves in some of their stores. A CVS spokesman declined to comment. A Walgreens spokesman did not immediately respond to CNBC's request for comment.

Gottlieb tweet

Congress legalized hemp-derived CBD late last year. However, the FDA says companies still can't add CBD to food or sell it as a dietary supplement. Selling CBD-infused beauty and skin-care products is viewed as far less risky.

The FDA and the Federal Trade Commission on Tuesday sent three warning letters to companies allegedly making unproven claims about CBD treating ailments like cancer, Alzheimer's disease and others.

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