FDA Commissioner Dr. Scott Gottlieb resigned from his post Tuesday.
"All of us at HHS are proud of the remarkable work Commissioner Gottlieb has done at the FDA," HHS Secretary Alex Azar said in a statement. "He has been an exemplary public health leader, aggressive advocate for American patients, and passionate promoter of innovation. I will personally miss working with Scott on the important goals we share, and I know that is true for so many other members of the HHS family."
The Washington Post first reported Gottlieb's resignation.
Gottlieb, who took the helm of the Food and Drug Administration in May 2017, was previously a consultant with close ties to the pharmaceutical industry, but he pushed to speed up the agency's approval of generic drugs and boost price transparency.
His resignation comes as Congress is starting its own work to bring down pharmaceutical prices.
Most recently, he publicly criticized the anti-vaccination movement, signaling he was willing to crack down on the trend from the federal level.
Early this year, Gottlieb pushed back on Twitter to speculation that he was leaving the agency.
"I want to be very clear—I'm not leaving," the commissioner tweeted on Jan. 3. "We've got a lot important policy we'll advance this year. I look forward to sharing my 2019 strategic roadmap soon."
President Donald Trump took to Twitter to praise Gottlieb for his tenure, saying the commissioner "has done an absolutely terrific job."
"Scott has helped us to lower drug prices, get a record number of generic drugs approved and onto the market, and so many other things," the president tweeted. "He and his talents will be greatly missed!"
The news took Capitol Hill by surprise Wednesday afternoon. Some leading lawmakers learned the news from reporters and didn't have an immediate comment.
But Sen. Bill Cassidy (R-La.) said he hopes the resignation won't slow the agency's record generic-drug approvals. "I hope that he's put in systems that will outlast him, because that's obviously the goal," the senator told Project Japan.
Sen. Richard Burr (R-N.C.), who opposed Gottlieb's proposal to ban menthol-flavored cigarettes in addition to flavors for vaping devices, said he thinks Gottlieb "is potentially one of the best commissioners we've ever had at the FDA."
Since last fall, Gottlieb has pushed hard on proposed curbs to teen vaping, prompting Republican outcry about regulatory overreach.
House Energy and Commerce ranking member Greg Walden (R-Ore.) said in a statement that in his years in public service he has "never worked with a more talented, forthright, and effective agency leader than Dr. Scott Gottlieb."
"While he might not necessarily be a household name, his work to bring new medicines to patients quicker, guard young people from products bad for their health, protect food safety, and work to find cures to deadly and debilitating diseases will have an enduring impact on the lives of every American," Walden said.