MarthaFHydrocortisone doesn’t dissolve in liquid well, therefore suspensions can be tricky. The pharmacy told us to shake it a long long time(~4-5minutes!) before we give it to our daughter. Anything less than that and the medicine may not be evenly distributed throughout the liquid and your kiddo may get less (or more) than you intended.
My daughter was 19lb and 29.5inches at a year and roughly on the same dose as your son. I’m just concerned cause we keep lowering her dose and not seeing much change in her 17-ohp levels. Frustrating, isn’t it?!