By Linda Searing

Older people who take a low-dose aspirin daily may be 20 percent more likely to develop anemia than those who do not, according to research. Anemia develops when a person has an inadequate number of healthy red blood cells, which are needed to carry oxygen to tissues throughout the body. People with anemia often feel tired and out of breath.

The research finding stems from the re-analysis of data from a study involving 19,114 people, most 70 or older, who did not have anemia and were generally healthy. They had been randomly assigned to take either 100 milligrams of aspirin or a placebo daily for about five years. In that time, participants’ blood tests showed that the levels of hemoglobin and ferritin — proteins that help indicate the amount of iron in the blood — had declined more steeply among those taking a daily low-dose aspirin than they had among those not taking aspirin.

The researchers attributed the increased risk for anemia among aspirin-takers to this iron deficiency. Aspirin of 100 mg or less is considered low-dose, with 81 mg being the most common dosage available for over-the-counter aspirin.

For years, people often took low-dose aspirin, which can thin the blood and help prevent clots, in hopes of preventing a heart attack or stroke. In 2022, however, medical advice changed. Now, taking low-dose aspirin is not considered medically appropriate for most adults who have not already had a cardiovascular issue.

The researchers wrote that their findings suggest that “periodic monitoring of hemoglobin should be considered in older persons on aspirin” to guard against the development of iron-deficiency anemia.