Certain medicines, like powerful anti-inflammatories used mostly to treat a very serious childhood disease, juvenile rheumatoid arthritis, are too risky for most other doctors to use because of a rare but serious potential side effect. These drugs are closely related to a commonly used artificial flavor suspected by Feingold to cause hyperactive behavior. From time to time, alert rheumatologists did see the same behavioral deterioration in a few of their patients taking these medicines (which they immediately discontinued if they could) and quickly understood that the phenomenon is a real one—but it only applies to a very small subset of patients. Because these observations weren't the result of rigorous study, they were sometimes mentioned to colleagues, but not published.