Effect of 81mg ASA on Blood Pressure
Low-dose aspirin (81mg) does not raise blood pressure and may actually have a small beneficial effect on blood pressure when taken at certain times of day. The evidence consistently shows that low-dose ASA does not interfere with the blood pressure-lowering effects of antihypertensive medications.
Evidence on ASA and Blood Pressure
Impact on Blood Pressure
- According to a large study analyzing data from the Hypertension Optimal Treatment (HOT) Study involving 18,790 intensively treated hypertensive patients, low-dose ASA (75mg daily) did not interfere with the blood pressure-lowering effects of antihypertensive agents 1
- In fact, some research suggests that low-dose ASA may have a small beneficial effect on blood pressure:
Time-Dependent Effects
- The timing of ASA administration may influence its effect on blood pressure:
- Evening administration of ASA (75mg) has been shown to lead to favorable drops in ambulatory blood pressure measurements and improvement of diurnal profile in high-risk cardiovascular patients 3
- A study investigating time-dependent effects found that low-dose ASA (100mg) administered at bedtime produced a statistically significant reduction in systolic blood pressure (approximately 2.3 mmHg) in healthy subjects, with even greater reductions (approximately 4.5 mmHg for both systolic and diastolic BP) in hypertensive patients 4
Clinical Implications
Safety with Antihypertensive Medications
- The American College of Cardiology Foundation/American Heart Association guidelines note that low-dose ASA can be safely used alongside antihypertensive medications, including ACE inhibitors 5
- No negative interaction occurs between ACE inhibition and the cardiovascular benefits of small doses of ASA 1
Recommended Dosing
- For cardiovascular prevention, low-dose ASA (75-150 mg daily) is recommended for long-term therapy according to European guidelines 6
- After coronary stenting, a daily aspirin dose of 81 mg per day is an accepted regimen based on risk of excess bleeding 5
Timing Considerations
- For patients with hypertension, administering ASA in the evening rather than morning may provide better blood pressure control 3
- This timing effect may be particularly beneficial in high-risk cardiovascular patients 4
Important Caveats
- The findings about ASA not raising blood pressure specifically apply to low doses (75-100mg) and may not extend to higher doses
- Individual responses to ASA may vary, and some patients might experience different effects
- The National Lipid Association guidelines recommend ASA 81mg daily for certain high-risk patients with elevated coronary artery calcium scores, suggesting its cardiovascular benefits outweigh potential risks 5
In conclusion, the evidence strongly indicates that low-dose ASA (81mg) does not raise blood pressure and may even have small beneficial effects on blood pressure control, particularly when administered in the evening.