WASHINGTON — Dr. Margaret Hamburg, commissioner of the Food and Drug Administration, will step aside next month after nearly six years at the helm of the agency overseeing many of the nation’s most contentious public policy issues and products representing about 20% of every dollar spent by ­consumers.

Hamburg, 59, said her decision to step down as FDA commissioner was prompted by the demands of the job and the length of time she has held the position. Dr. Stephen Ostroff, the FDA’s chief scientist and a former official at the Centers for Disease Control and Prevention, will become the agency’s acting ­commissioner.

Under Hamburg’s stewardship, the FDA streamlined drug approvals. It approved 41 novel new drugs and biologics in 2014. Hamburg also has addressed safety issues over generic drugs made in India and food imported from China. Additionally, she directed the agency’s campaign to implement calorie-count labels on restaurant menus.

The sprawling agency’s reach continues to expand. During Hamburg’s tenure, Congress directed the FDA to overhaul the nation’s food safety system. The subsequent Food Safety and Modernization Act was signed by President Obama in 2011. Congress also granted the FDA authority to regulate the tobacco industry. The agency has proposed rules to regulate electronic cigarettes that could be implemented this year.

“Throughout her tenure, Dr. Hamburg has been a tireless advocate for patient safety and a leader in efforts to assure that FDA decisions are guided by scientific principles,” said Ralph Neas, president and chief executive officer of the Generic Pharmaceutical Association. “She has also been instrumental in the passage and implementation of the Biosimilars User Fee Amendment (BsUFA). Dr. Hamburg’s efforts have been particularly important in this area, as the first biosimilars will soon be available in the United States.”

Francis Collins, director of the National Institutes of Health, praised Hamburg as “a remarkable leader with extraordinary scientific and medical sophistication, as well as excellent judgment and unquestioned dedication to the public good.”

But critics complained that Hamburg could be too cozy with industries regulated by the FDA.
“I’m pleased to see her go,” Dr. Andrew Kolodny, president of Physicians for Responsible Opioid Prescribing and the head of an addiction treatment center in New York, told The Washington Post. “Her administration consistently put the interests of the drug companies ahead of public health.”

Hamburg, a daughter of physicians, served as health commissioner of New York City from 1991 until 1997. She is a graduate of Harvard Medical School.