Blood thinning effects of varying doses of aspirin?

Aspirin: Aspirin works by 'poisoning' platelets. Once all the platelets have been affected by the Aspirin , if you stop there will daily be more platelets entering circulation that are not 'poisoned'. This is why Aspirin is given daily. One whole aspirin(325mg) a day generally will ensure that all the platelets are hit. The 81mg/day dose is effective for about 80% of people.

Baby aspirin is best: Based on a recent trial that looked at dosing aspirin, amongst other things, there seemed to be no advantage to higher doses of Aspirin in reducing cardiovascular events in patients who had coronary events. Overall we generally recommend no more than 81 mg of Aspirin for most patients when talking about cardiac risk reduction. Speak with your md for specific recommendations for your condition.