I have liver problems and different pills affect me differently, also I have endocrine problems, so steroids don't always work as planned. I found that the different brands and types of prednisone matter a great deal. I cannot take medrol dosepack anymore--though I could until fairly recently, medrol makes me have horrible psychiatric side effects and other bad reactions that make it unbearable to take. I mentioned this to my rheumie and he tried regular prednisone tablets (I don't know the brand--but he said this medication was well tolerated by the pickiest) and I can take that. I have bad psychiatric and other side effects on too low a dose or two high. There seems to be a perfect dose that I need to start at and taper length that I need. A lower longer taper was misery for me. A shorter taper at 20mg works for me with my liver and screwed up endocrine, but I should be on prednisone daily for my endo anyway, but can't get it yet.
Anyway, sorry for the ramble, the point is that if need be, there may be other steroid options. I have taken cortisone as well as some dexamethasone IV, which does little for me but relieve pain and make life more bearable, other people it would zonk them out.
You might also see what her endocrine and liver function is because if she has problems there, which is common with autoimmune disease, steroids dont always work the way they should.
I wish your sister the best, she is lucky to have a nice sis like you.
--Sometimes I think the surest sign that intelligent life exists elsewhere in the universe is that none of it has tried to contact us. Bill Watterson (1958-) cartoonist "Calvin and Hobbes"
Ills--Sjogrens-Lupus-like AI Disease, Hashis, Vitiligo, spinal stenosis/fusion with plate, salivary/lymphectomies, Diabetes, NAFLD, COPD, RLS, neuropathy, trigonitis, hystero, diffuse brain atrophy, GI nightmare
Meds--Plaquenil, Evoxac, Metformin, Synthroid, HCTZ, Estradiol patch, Prosed, Detrol, Klonopin, Ultram, Vicodin, Restasis, Albuterol, steroid injections and pred prn