I agree with Carrie - doctors are too quick to blame the parents if a child with  CAH has a weight problem, which is very frustrating!  It sounds as if you daughter is oversuppressed Lisa, as this would both slow growth and cause weight gain, which are the effects you mention.  Ask to see her blood test results, so you can see for yourself how well controlled she is.  Dex can be more difficult to fine tune due to the fact it is a far stronger steroid than hydrocortisone but if properly titrated it can be a very successful treatment method, and I know there are many on this board whose children have done well on it.  It doesn’t suit all though (as with any drug!) so switching back may be an option to consider but I do think your daughter’s specialist should talk things through with you and explain why he thinks dex is the best treatment in her case.