A 35-year-old man was admitted to the hospital with myalgias and generalized weakness. Two weeks before, he had abdominal pain, decreased oral intake, nausea, and vomiting. He denied diarrhea. One week before admission, he developed muscle weakness that worsened until he was unable to get out of bed without assistance. His medical history was unremarkable. His only reported medication was over-the-counter ibuprofen for chronic back pain, 2,400 to 3,200mg daily for several months. He denied alcohol or solvent abuse.