I have not asked about topical steroids but I have asked about oral steroids and this was her response:
Steroids can cause severe immune suppression in rabbits leading to really bad stuff like hepatitis, encephalitis, bleeding stomach ulcers, bone problems, and even death. I typically reserve steroid use as a “last ditch effort” drug prior to considering euthanasia. Though I see vets use them in bunnies, it is generally a bad idea in the opinion of most vets who treat rabbits routinely.
This is a list from the disabled rabbits web page that they recommend for urine scald (but I think would work for blisters too) – I use the Silvadene quite often for urine scald and red skin areas around my rabbits anal areas when they get sore from washing from poopy butt:
Bunny Safe Creams for Urine Scald:
Silvadene Cream [known as Flamazine in Canada]
CEH Ointment (Calendula/Echinacea/Hypericum)
Rescue Remedy Cream
Neosporin (but not Neosporin Plus)
Panalog
Bactoderm (mupirocin) ointment
Calendula Gel/Cream
A + D Original (not with added zinc)
Oxyfresh PetGel
Bag Balm
Aloe Vera Gel