The measure was applauded by Senators Richard Durbin of Illinois, a Democrat, and Charles Grassley of Iowa, a Republican, who together have tried to pass similar legislation. “Direct-to-consumer prescription drug advertisements are everywhere, and they tell you just about everything imaginable about the drug, other than its price,” the senators said in a joint statement. “We believe American patients deserve transparency.”

The drug industry has pointed out that many patients with insurance coverage pay far less than the list price. “We are concerned that the administration’s rule requiring list prices in direct-to-consumer (DTC) television advertising could be confusing for patients and may discourage them from seeking needed medical care,” said Stephen J. Ubl, chief executive of the Pharmaceutical Research and Manufacturers of America, the industry trade group.

On Wednesday, the lobbying group announced it had set up a website that would link patients to financial assistance for drugs as well as to company websites that provide data on list prices, typical out-of-pocket costs and sources of financial assistance.

The manufacturer Johnson & Johnson said this year that its ads would begin disclosing the list price, starting with those for the anti-stroke drug Xarelto that carries a $448 monthly list price, along with information about the typical consumer co-payment.

“If you’re ashamed of your drug prices, change your drug prices,” said Mr. Azar, who was a top executive with pharmaceutical giant Eli Lilly and Company before joining the Trump administration in January 2018. “It’s that simple.”

He compared the new requirement to a similar one for the automobile industry. “We have for over 50 years required that car manufacturers and car dealers post the sticker price of cars on the windows of their cars, and be transparent about that,” Mr. Azar said. “It’s a starting point.”

The new rule, he added, could prompt drug companies to lower their costs out of fear consumers would reject their products based on sticker shock alone.