Aspirin can make spironolactone (Spirolac) work less well as a water pill. Spironolactone turns into an active form called canrenone, which has to pass out into the tiny tubes of the kidney to do its job. Aspirin blocks this step, so you may pass less extra urine and the medicine may not lower swelling or blood pressure as well as it should.
These medicines are often taken together with some care. Your doctor may change a dose, space them apart or check on you more often. Make sure your doctor and pharmacist know you take both.