http://www.drugs.com/drug_interactions.html

This site allows you to list all the different meds you take, adds them to your personal lists, then you merely hit the button and it will tell you the side effects, interactions, etc that exist when you combine a new med with what you a currently taking. It is a section of Drugs.com and 100% free. You must register with the site to save your database, that also is free and you provide no personal information other then an Email address. I found it very interesting and can see its advantages if you want to make sure what drugs are safe to mix. also mentions "the grapefruit question"
NEON