The pharmacist who originally filled my rx explained it to me, and I hadn't been diagnosed as yet with EDS, although of course I had it. It took about two years on the medication before the weakness became apparent, but when I tried Florinef again a few years later, it only took a week before I started having trouble. Muscle weakness and wasting are listed as side effects if you look at the full prescribing info for Florinef and not just the patient version. Sadly, I don't remember the pharmacist's explanation at the time (I was only semi-concious), and I've had doctors tell me it just couldn't be. However, as a former chemist, I'm going to trust the pharmacist and the PhD chemists at the drug company over a doctor when it comes to meds. If you're really curious, you can always call the drug company. Most of them are good with consumer questions.
I'm sorry to hear you had such a bad experience on Florinef. Have any of your doctors explained the mechanism of how a mineralocorticoid caused muscle wasting? Is it something specific to EDS? Or is it a rare reaction that could happen to anyone? Or don't they know?
Out of the many people I've known who've taken florinef/fludrocortisone, I've heard of various side effects but never this one, so I'm really curious to know more. Especially if it is something that has to do with EDS specifically, as of course there is a significant subset of those with dys that have EDS.
I never got sick until I started taking Florinef. Then I got everything. Not only that, but a 24 hour virus would last a week. I've been off Florinef a few years now because it caused severe muscle weakness and wasting in addition to all the illness. My immune system has not returned to its normal super efficient state though