One of the best ways to make yourself a less helpless human being is to gain a basic understanding of the medicines we use today. In Memorizing Pharmacology, Tony Guerra touches on the top 200 drugs in use today and tries to provide some tips on how you can memorize the names and functions of each.
Though the focus is on memorization, presumably for a medical school exam, Guerra provides additional context to each drug, often contrasting them with similar drugs and giving examples of why it might be prescribed. He not only goes over the primary chemicals, but he also touches on common multi-compound formulations such as Tylenol PM (acetaminophen/diphenhydramine) and Excedrin Migraine (acetaminophen/aspirin/caffeine), making this book useful even for the casual reader.
I loved the sample exam and discussion given towards the end of the book. The discussions there help greatly to understand the decisions medical doctors make. Here's a sample question given:
Contrast one over-the-counter anti-diarrheal and one prescription antidiarrheal and the reason for choosing one over the other.
Even if you never plan on becoming a pharmacist or doctor, you're likely to encounter a great number of these medications within your lifetime. Having a baseline knowledge of them will not only help you understand your treatments, but it will help you make educated decisions next time you find yourself in the medicine aisle.