Streptococcus pyogenes shouldn't be taken lightly. Left untreated, an infection with germ can trigger an autoimmune disease that damages the heart. NIAID/Flickr.com hide caption

itoggle caption NIAID/Flickr.com

Many hospitals are perilously close to running out of a form of methotrexate that's necessary to inject in high doses to treat certain forms of cancer. iStockphoto.com hide caption

itoggle caption iStockphoto.com

The scarcity of ADHD medications is a problem faced by an untold number of children and adults with the disorder. GoodMood Enterprises/iStockphoto hide caption

itoggle caption GoodMood Enterprises/iStockphoto