Dear Debbi, I’m an adult male with NSWCAH.  Throughout my entire life, I’ve gotten headaches whenever I’ve taken my hydrocortisone late, or my body has burned through my normal dose due to increased stress/physical activity.  I can literally feel when I’m starting to "run low".  As Kathy suggested, perhaps you might try increasing the frequency of your son’s dose without increasing his overall daily intake to keep his levels more even throughout the day.  Yes, dehydration may be playing a factor, as it has for me on occasion, but if his headaches are occurring regularly, I’d suggest modifying the frequency of his doses.  Hope this helps, and good luck.  Best, Eric