Women who take daily high doses of the over-the-counter (OTC) pain killers ibuprofen and, acetaminophen are much more likely to develop high blood pressure than women who do not use these drugs, according to new research.
The study looked at the medical records of more than 5,000 women-ages 34 to 77-for up to eight years, and found that those who took 500 milligrams (mg) or more of acetaminophen daily were twice as likely to develop high blood pressure as women who did not take the drug.
Women ages 51 to 77 who took an average of 400 mg of ibuprofen daily were 80% more likely to develop high blood pressure than women of the same age who did not take this drug. Younger women (ages 34 to 53) who took the same dose were 60% more likely to develop high blood pressure, according to the study.
Interestingly, the researchers did not find that aspirin increased women's chances of developing high blood pressure.
The mechanism by which the medications could raise blood pressure is uncertain, explains Dr. Clarence Grim, a professor of clinical medicine at the Medical College of Wisconsin, and an expert on high blood pressure. There is a "general hypothesis" that they might increase blood levels of sodium by affecting kidney metabolism, he says.
Another possibility, says Dr. Gary C. Curhan, an associate professor of medicine at Harvard Medical School and a member of the research team, is that the painkillers may influence blood vessel relaxation. Acetaminophen is known to affect levels of nitric oxide, a substance that is important in blood vessel control, he says.
Ibuprofen and acetaminophen "are used so frequently and so widely that they could be one reason why the incidence of high blood pressure is so high," Curhan says.
Grim suggests that people who take the pain killers frequently make sure they tell their physicians how often they are taking them. And, he advises, "Be sure to keep an eye on your blood pressure. Even small changes in blood pressure can be very significant.
"This is another thing we need to add to the list of items that raise blood pressure, at least for women," Grim says.
The new research involved only women because men generally use painkillers less often. However, studies of a possible relationship between these drugs and high blood pressure in men are just beginning, and Curhan says he expects the results will be the same as for women.
"Call me back in four or five years and I'll have some information for you," Curhan says.