Aspirin . For fevers due to colds or fu, for other minor aches and pains, the advice is often the same : take two aspirin . It may be the most commonly used drug in the world. but it is not the best understood drug in the world. Scientists are continually conducting experiments to find out why aspirin has the various results that it does. In the process, they have discovered some new effects of aspirin some good and some bad. These include additional evidence for a six-year old theory that aspirin may they help prevent a second heart attack in heart victims.