Here are a couple of sources. I don't have any sources off the top of my head. I first learned about this about 19 years ago. The basic premise is that the lack of blood flow to the organs causes tissue death including the liver (chemical induced hepatitis) and kidneys. For example I know of 4 people who developed kidney failure after taking a single recommended dose of ibuprofen. People with poor circualtion to begin with are at greater risk. These include those with congestive heart failure, diabetes, and Raynaud's.