My daughter heard a topical paste of aspirin can help reduce inflammation of acne - I'm concerned about possible blood thinning effects - possible?

Acetylsalicylic acid. Aspirin (acetylsalicylic acid) is an old standby for acne & is the active ingredient at ~ 2% in most otc face washes. It works by loosening old skin cells & opening blocked pores. I would be reluctant to make your own paste as the material in higher strengths is painted on warts to destroy them.(& would likely burn burn the skin)skin application has negligible effect on the blood.
Topical meds. Most meds are quickly absorbed through the skin. If you do not believe it...Crush up a fresh clove of garlic, and stand on it. The skin on the sole of the foot is pretty thick...But soon you will taste the garlic. The following post was written by a chemist. Interesting facts. Yes it is absorbed..But there are other concerns in addition to the bleeding.