>>>> "I have a full patient handout on headaches from Medlink. I don't think it would be legal for me to scan and share it" <<<<

According to MedLink TOS, itself, apparently, within reason anyway, you can indeed:

2. Terms of Use. Our Service is intended for your personal, non-commercial use. It and all items of Content that we publish, whether on the Internet or on specific media, are protected by copyright under U.S. and international copyright laws and owned or controlled by us or the party credited as the provider of Content. You agree to abide by all additional copyright notices, information, or restrictions contained in any Content accessed through the Service.
>>>> "You may download or copy a small number of items of Content (i.e., less than 10 percent of items per year in each category of Content) for your personal use only, provided that you retain or add all relevant copyright and other notices. You may distribute limited numbers of copies of excerpts of such materials for noncommercial, educational purposes." <<<<