Due respect to Unknown. I am suspicious about her credentials as her information is signficantly wrong. Might I address a few things? 1. Aspirin does nothing to specifically thin the blood. The viscosity of blood is identical for those who take aspirin as for those who do not. Aspirin DOES inhibit the aggregation of platelets. This is a covalent bond and therefore an irreversible bond. It is only reversed when your body produces more platelets. 2. Aspirin has been shown to reduce the incidence and severity of stroke and myocardial infarctions. Further those who take aspirin has shown lower incidence of colon cancer. It is the easiest and single best thing you can to to reduce your risk for serious vascular events in those have even a single risk factor for cardiovascular disease: high blood pressure, high cholesterol, family history, diabetes, smoker, and advanced age. 3. Overdoses (due to extreme acid content) of aspirin can be manifested in reduced serum potassium but normal daily doses do not have that risk. (The kidney in an effort to get rid of the acid, looses potassium, with overdose. In normal situations the kidney does not have to resort to spilling potassium in an effort to normalize the bodies pH) 4. The one area of concern is your stomach and small intestine. Some people can have stomach upset and even a bleeding ulcer with the use of daily aspirin. Using 81mg has been shown to afford nearly all of the benefits of 325mg with less risk for GI bleed. 5. Coumadin and aspirin can be tolerated in some particularly high risk patients. This is commonly done in a cardiology practice. 6. A blood test such as PT (pro time, sometime discussed as INR) or PTT (Partial Prothrombin Time) are not changed by use of aspirin. A lab study done less often, template bleed time, can be effected by aspirin, however. I hope this clears up some of what has been written about aspirin. If you need references on all that I have written above, I would be happy to supply them. Good luck.