Furthermore, whether certain indications for analgesic use, particularly headache, mediate the association is unclear. Harvard researchers conducted two prospective cohort studies among older women 51 to 77 years of age (n=1903) from the Nurses’ Health Study I and younger women 34 to 53 years of age (n=3220) from the Nurses’ Health Study II who completed detailed supplemental questionnaires pertaining to their analgesic use and who did not have hypertension at baseline. They analyzed incident hypertension according to categories of average daily dose of acetaminophen, nonsteroidal anti-inflammatory drugs, and aspirin. Information on indications for analgesic use as well as relevant confounders was also gathered prospectively.

They found that compared with women who did not use acetaminophen, the multivariable adjusted relative risk for those who took >500 mg per day was 1.93 among older women and 1.99 among younger women. For nonsteroidal anti-inflammatory drugs, similar comparisons yielded multivariable relative risks of 1.78 among older women and 1.60 among younger women. These associations remained significant among women who did not report headache. Aspirin dose was not significantly associated with hypertension.