Imagine you could take a medicine that prevents the decline that come with age and keeps you healthy. Scientists are trying to find a drug that has these effects. The current most promising anti-aging drug is rapamycin, known for its positive effects on life and health span in experimental studies with laboratory animals. To obtain the maximum beneficial effects of the drug, it is often given lifelong. However, even at the low doses used in prevention for age-related decline, negative side effects may occur, and it is always desirable to use the lowest effective dose.