While many popular over-the-counter painkillers have been linked before to high blood pressure, acetaminophen, sold as Tylenol, has generally been considered relatively free of such risk.
It is the only one that is not a non-steroidal anti-inflammatory drug or NSAID, a class of medications the federal government just required to carry stricter warning labels because of the risk for heart-related problems. Those include ibuprofen (sold as Advil and Motrin) and naproxen (sold as Aleve). Many had turned to those painkillers in the wake of problems with prescription drugs, such as Vioxx.
However, the new study found that women taking Tylenol were about twice as likely to develop blood pressure problems. Risk also rose for women taking NSAIDS other than aspirin.
"If you're taking these over-the-counter medications at high dosages on a regular basis, make sure that you report it to your doctor and you're checking your blood pressure," said Dr. Christie Ballantyne, a cardiologist at the Methodist DeBakey Heart Center in Houston who had no role in the study.
The research found that aspirin still remains the safest medicine for pain relief. It has long been known to reduce the risk of cardiovascular problems and was not included in the government's requirement for stricter labels for NSAIDs.
The study involved 5,123 women participating in the Nurses Health Study at Harvard Medical School and Brigham and Women's Hospital in Boston. None had had high blood pressure when it began.
Results were published online Monday in the American Heart Association journal Hypertension.
"It certainly sets the basis for more studies," said Dr. Stephanie Lawhorn, a cardiologist at St. Luke's Mid America Heart Institute in Kansas City. "Most of the time we think that things like acetaminophen are fairly safe drugs."