Long-term, heavy ketamine use is associated with memory problems, depression and anxiety. The drug may also cause gastrointestinal problems, abdominal pain popularly known as “k-cramps” and uropathy, which is a blockage in the urinary tract that can lead to infections, or UTIs.

Asked about the black eye, Musk said it happened while he was playing around with his son, X Æ A-Xii, who he calls X. He also had an eye injury in the video Thursday announcing SpaceX’s "tentative" game plan to bring humans to Mars.