Under the AMA policy, health-related products include vitamins, dietary supplements, over-the-counter medications, safety devices such as child seats and bicycle helmets, skin creams, sun block and special foods.
AMA policies have no legal authority, but they carry enormous weight. The group is the nation's largest organization of doctors. Its 290,000 members make up about one-third of U.S. physicians, and it spends more than $8 million a year lobbying Congress and other levels of government.
In-office sale of such products "presents a financial conflict of interest, risks placing undue pressure on the patient and threatens to erode patient trust and the primary obligation of physicians to serve the interests of their patients before their own," according to a five-page report by the AMA's Council on Ethical and Judicial Affairs.
Some doctors complained the policy is unfair to physicians who supply needed products, or practice in areas where such items would otherwise be unavailable.
"This report, as I read it and as I understand it, precludes me as an orthopedic surgeon from selling a patient a pair of crutches if I'm to make even a dollar on that pair of crutches," said Dr. Thomas E. Price of Roswell, Ga.
Price said there's nothing wrong with doctors making money from products, since it helps make up for losses from managed care and the treatment of uninsured patients.
However, there may be some exceptions to the guideline.
"If patients cannot get their products from another source, if they are a long way from a pharmacy or they have a broken leg and they can't get crutches without substantial problems, then those are reasons doctors might have products in their office," Dr. Nancy W. Dickey, former president of the American Medical Association, told CBS News.
"But even then, physicians should be selling them at cost, as a service, rather than as a profit line," she added.
The AMA policy says physicians may distribute such products ethically free or at cost. Physicians should inform patients about their financial arrangement with the manufacturer or supplier, it added.
The policy passed the group's House of Delegates by a six-vote margin Tuesday.
The AMA cannot enforce the guidelines by taking away doctors' licenses or putting in official complaints. Instead, the organization relies on educating the public to their rights, and doctors communicating their expectations among their peers, Dickey explained.
"What we can do is establish a standard, tell patients what that standard is, and then physicians help enforce the standard by telling their peers what they expect and patients can ask questions of their doctor, when they say, 'Gee, I thought you weren't supposed to do this' or maybe empower the patient to simply say, 'I thinI can get that product cheaper some place else,'" Dickey said.