Common pain reliever linked to higher blood pressure when used regularly

Regular use of paracetamol was found to increase blood pressure within two weeks in a clinical trial involving people who already had hypertension. The result calls into question the long-held belief that this widely used painkiller has no impact on the cardiovascular system.

Paracetamol, also known as acetaminophen, is often viewed as an alternative to anti-inflammatory painkillers such as ibuprofen. While those medicines are known to raise blood pressure, the trial suggests paracetamol may also deserve closer attention when used on a regular basis.

Researchers at the University of Edinburgh recruited 110 adults with high blood pressure and compared paracetamol with an inactive placebo. The PATH-BP study, published in Circulation, tracked blood pressure directly rather than waiting to see how many heart attacks or strokes occurred.

Participants took one gram of paracetamol four times a day for two weeks, then switched to a matching placebo for another two-week period. The treatment order was randomly assigned, with a break in between, allowing each participant to act as their own comparison.

The study was also blinded, meaning neither the participants nor the researchers knew which treatment was being given at the time. That approach reduced the chance that expectations could affect the findings.

Blood pressure was measured during everyday life rather than in a single clinic visit, giving a more complete view of its effects. The main analysis focused on average daytime systolic blood pressure, the upper number that reflects the pressure when the heart contracts.

Paracetamol raised this reading by about 4.7 millimeters of mercury compared with placebo. Diastolic pressure, the lower number that measures pressure between heartbeats, increased by about 1.6 millimeters of mercury.

Those changes may appear modest, but a lasting rise in blood pressure can be significant when it affects many people or those already at higher risk of heart disease. The trial demonstrated a measurable effect over a short period.

However, it did not show that participants experienced a 20% increase in heart attacks or strokes. Any estimates about those outcomes come from other research on the effects of sustained blood pressure increases, not from events observed in this study.

The dose used in the trial also matters. Researchers tested regular use of four grams a day, so the findings do not tell us how lower doses, occasional tablets, or short-term treatment for a headache might affect blood pressure.

Longer studies could help show how blood pressure changes over time and how any risk compares with the pain-relieving benefit. The results also do not mean that other painkillers are automatically safer, since they come with their own risks and limitations.

The trial adds new evidence to a routine prescribing decision. Paracetamol remains a familiar medicine, but regular high-dose use should not be assumed to be neutral for blood pressure simply because it belongs to a different drug class from ibuprofen.

Source: University of Edinburgh.