Thursday's proposal by the Food and Drug Administration is part of a series of government steps to help prevent deadly medical mistakes that claim tens of thousands of lives each year.
An estimated 7,000 hospitalized patients die annually because of drug errors, where a wrong drug or a wrong dose is dispensed. The bar code system will allow nurses and others to check electronically that the drug is the proper one.
"I am so excited about the possibility we now have to reduce patient deaths and improve patient safety and the quality of health care in America," Health and Human Services Secretary Tommy Thompson said.
Patient safety advocates and industry groups welcomed the initiative.
The proposed regulation, which is expected to be finalized early next year, also will apply to most drugs sold over the counter. Officials expect the bar coding system will be useful in nursing homes as well as hospitals.
Drug makers will have three years to comply, but federal officials expect they will begin using the codes more quickly.
With a bar-code system, health workers scan a code on a patient's wristband to show what medicines are needed and when. Then they scan the intended medication. If they picked the wrong drug, the wrong dose or a pill version when a liquid was required, a computer beeps an alarm.
The computer can be programmed to catch other errors; for instance, if a doctor prescribes a drug the patient is allergic to or a drug that will react dangerously with another medication.
"This adopts a technology that is very widely used in other industries," said Mark McClellan, the FDA commissioner. "Grocery stores and other parts of our economy that people think of as lower-tech are ahead of our health care system."
McClellan estimated that the bar code plan will cut medication errors in half and prevent more than 400,000 medical problems over 20 years.
Michael Cohen of the nonprofit Institute for Safe Medication Practices said the impact is likely to be even greater. He cited one study that found bar codes reduced medication errors by 80 percent.
Veterans hospitals have found medication errors plummeted after they adopted a bar-code system. But because the codes are not now affixed to medications, Veterans Affairs pharmacists have been forced to relabel drugs so they can be electronically identified.
Hospitals will not be required use the bar code systems, but federal and private officials expect that it will be widely popular.
"I think hospitals will be quick to adopt it," Cohen said.
Also Thursday, the FDA proposed changes in how doctors and drug manufacturers report adverse reactions - both side effects and errors - to the government in hopes of more quickly uncovering preventable problems. The reporting system will be standardized so drug companies can submit one report to authorities in this country, the European Union, Japan, Canada and Switzerland.
Among the changes:
Medical errors have garnered increased concern since a teenager died last month after doctors at Duke University Medical Center gave her a heart-lung transplant from a donor with the wrong blood type. But the Institute of Medicine estimates that medical errors contribute to up to 98,000 deaths each year.
Pharmacists and drug manufacturers long have supported the idea of bar codes, although companies have some reservations about just how much information should be included.
The FDA estimates it will cost the drug manufacturers about $53 million to change their labels and comply. Hospitals are expected to invest an additional $7.2 billion in order to use the technology, the FDA said.
The FDA's proposal will be open for public comment - 90 days on the bar code plan, 120 days on changes to the adverse reactions reporting system - before the new rules take effect.
By Laura Meckler