Hi , I have gone through question and understand your concerns.
Its
aspirin it basically blood thinner and help to reduce mortality and long term cardiac complications of
high blood pressure but it do not lower down the blood pressure.
At this moment Diet and Exercise modifications are very important:
High fibre diet, green leafy vegetables, fruit.
Cut down the processed food. White bread, doughnuts, white sugar, pizza should be completely avoided.
A 40 minute physical activity every day like morning walk, evening walk or a visit to the gym or swimming pool.
And you should have his blood pressure record daily one at morning and than 2nd reading at evening. Monitor blood pressure for 07 days and than consult your physician.
Its likely that with diet and exercise modifications he will get his blood pressure well controlled.
Hope this answers your question. If you have additional questions or follow up questions then please do not hesitate to ask. I will be happy to answer your questions.
Wishing you good health.