The new rules of conduct issued on Friday also ban visits to "non-reputable establishments", presumably including strip clubs, and say staff must obey US laws even while abroad. A spokesman said they were effective immediately.
The new rules were issued two weeks after the scandal erupted over allegations that secret service agents and military personnel brought prostitutes to their hotels during a night of drinking and carousing in the Colombian city of Cartagena, just before President Barack Obama arrived for a summit.
The secret service this week began looking into allegations of similar misbehaviour before a 2011 presidential trip to El Salvador, a report that would appear to contradict official government arguments that the Colombian episode must have been an aberration.
The rules were issued as the agency sought to close a chapter in its worst case of alleged misconduct in decades, which embarrassed the United States and overshadowed Obama's participation in the Summit of the Americas.
The new rules issued on Friday say that "foreign nationals, excluding hotel staff and official counterparts, are prohibited in your hotel room."
"Alcohol may only be consumed in moderate amounts while off-duty on a TDY (temporary duty) assignment, and alcohol use is prohibited within 10 hours of reporting or duty," the rules say.
Furthermore, alcohol may not be consumed at all at the hotel where the person being protected by the Secret Service is staying once that person has arrived.
From now on, a member of the agency's professional responsibility section will accompany staff who travel on "car planes," and give staff ethics briefings before they leave, the rules say. The employees in Cartagena were support personnel who came over on the plane to Colombia that brought the president's armoured vehicles.
Twelve secret service employees were implicated in the Colombia matter. Eight have left the agency, three were cleared of serious misconduct and one is being stripped of his security clearance. Twelve members of the military were also implicated and that investigation is ongoing.
Earlier, a senior lawmaker said his committee is considering sending investigators to Colombia in the coming weeks to gather information in an expanded inquiry into the misconduct.
Representative Peter King, the Republican chairman of the House of Representatives homeland security committee, said his staff will move to a "full-scale" investigation after it receives answers to 50 questions the panel posed to secret service director Mark Sullivan about this month's incident.
Neither King nor another senior House lawmaker, Democratic Representative Elijah Cummings, said they saw a weakening of support for Sullivan in Congress despite reports of other secret service misbehaviour.
"In my estimation, he is doing all he can do. ... Rumours are coming in and he's following each one of them. He's looking into every single rumour that comes in," Cummings said.
Cummings, the top Democrat on the House oversight and government reform committee, which also is looking into the matter, said Sullivan plans to have 100 top secret service employees participate in a "very intense" ethics course next week.
"I'm not into being a morality cop, but what happened in Colombia was clearly wrong because it put security at risk," King said outside the House chamber, adding that his committee "probably in the next few weeks" would send investigators to Colombia as part of the inquiry.
The secret service so far has not been able to validate the allegations about El Salvador made in a report Thursday by KIRO-TV news in Seattle, King said. The station is part of the CBS-Cox media group.
"They have gone through the trip file, and spoke with some of the people who were on the trip, the supervisors, and so far it's nothing," King said. "And they are talking to the reporter and trying to find out who his sources are."
