A mate of mine broke a finger when learning to ski. He had it taped up and took Ibuprofen to see him through his skiing holiday. He started feeling ill on the final day and brought up blood on the way to the airport but decided that rather than miss his flight, he'd see a doctor when he got back to the UK. He had a wretched flight. As he finally walked in his door, he started vomiting large quantities of blood. He managed to phone for help before collapsing and fortunately for him, an ambulance was nearby at the time. Paramedics arrived on the scene in less than 5 minutes and found him lying in a pool of blood. They saved his life, but it was a very close call.
The problem turned out to be a perforated ulcer due to the Ibuprofen. It's rather put me off the stuff!