Nguyen, R.B., Milsten, A.M., and Cushman, J.T. (2008). Injury Patterns and Levels of Care at a Marathon. (Abstract only.) Prehospital Disaster Medicine. 23(6):519-25.
The authors analyzed medical care reports from five first-aid stations set up along a marathon route. The primary reason for seeking medical attention was "medication request;" secondary reasons included musculoskeletal injuries, dizziness, dermal injuries, and headache.