For years, low-dose aspirin has been described as a panacea to ward off heart attacks, strokes and other cardiovascular disease. New guidelines, though, suggest that aspirin should not be prescribed to most adults who are in good cardiovascular health and that the risk of internal bleeding often outweighs the benefit.

The American College of Cardiology and American Heart Association released the new guidelines on Sunday. They come on the heels of studies released last year that said daily low-dose aspirin — 100 milligrams or less — did not help older adults who do not have cardiovascular disease. Those results, published in three articles in The New England Journal of Medicine, surprised physicians and patients alike who for years believed aspirin would prevent any number of heart-related ills.

The authors of the new guidelines said low-dose aspirin should not be routinely given as a preventive measure to adults 70 years and older or to any adult who has an increased risk of bleeding.

“The guidelines are for people with no clinical signs of heart disease or stroke,” said one of the authors, Dr. Erin Michos, the associate director of preventive cardiology at Johns Hopkins School of Medicine, in an interview on Monday.