Finally getting back to you. Here are a few thoughts and ideas.
1. Might be a good idea to flush out any residue/toxicity from the prednisone from his system. The kidneys and liver are most important:
Milk Thistle for liver
Cornsilk to flush out kidneys
Do these at the same time. Cornsilk tea is cheap and tastes nice, a very good and gentle diuretic that would be the best one to use I think. I would take the Milk Thistle for some days, and he could drink a couple of cups of Cornsilk tea a day.
He should stay hydrated and eat juicy foods.
Since prednisone and his reactions are considered “Hot”, cooling foods would be appropriate, doesn’t necessarily mean ice cold or from fridge; but raw, salads and lettuce, non-heating vegetables and sort of plain foods.
Milk is very good for detoxifying. Ayurveda recommends bringing milk to a boil first as that breaks down proteins for easier digestion and much less congestion. I usually boil 2 quarts and then when cool store in the fridge. If I drink unboiled milk I get much more congestion; with boiled milk none.
Cilantro is specific for detoxifying and cooling the body, and also for skin issues. Chopped up fine and added raw to foods, and also can be blended with a little water, strained, and drunk, and/or applied to the skin for cooling and healing.
Turmeric is fantastic and you can almost never go wrong with it. Strongly anti-inflammatory and good for all kinds of skin issues. 1 tablespoon a day is perfectly safe, I take about 1 1/2 t a day. Golden milk - boiling milk and turmeric together - is another way. I add to my herbs and cook with it.
Red Clover which makes a decent tea is good for skin and cleansing the blood, it is cooling.
There are some more Ayurvedic herbs that could be helpful but since your husband is feeling better I won’t burden you with more.
Regarding his face being leathery, I assume that will heal in time as the skin renews itself. Does he feel discomfort too? Does his face feel itchy or burning or hot? I have awful skin (ultra sensitive and reddens easily) so in the summer I make spray bottles with 8 oz glass bottles, and put about 1 or 2 drops of peppermint oil and fill with water, very cooling.
Better yet would be food grade Rosewater (at Middle estern or Indian groceries, I buy on Amazon, Cortas brand) and that can be put in spray bottle as is, excellent for cooling the skin, strongly anti-inflammatory, anti-bacterial, and softening and soothing to the skin. I use daily and am never without it.
I would completely avoide soap, and to cleanse the face I would recommend oat flour. Wet face, put a bit of oat flour in palm and wet with a bit of water, and massage gently into the skin, and rinse. Best to tightly close eyes (ask me how i know).
I stopped using soap on my face about 35 years ago. I only cleanse with oat flour and besan flour (Indian groceries) and make my own facial cleanser with those flours and powdered herbs. Maybe that’s why I have no wrinkles?
One more - about diet. For now until all reactions are gone best to avoid things like chilis, garlic, hot spices etc. Let me know how things go.
Pinging the list - posted info about skin issues, prednisone reactions, and Parkinson’s.
Can you share your recipe for cleanser? I cannot eat grains but I assume that applying oat flour to face would not cause any issues since not ingested? (Oat flour) do you buy that, or grind up oatmeal to make the flour?
I wash my face by scrubbing it with a paste of bicarbonate and water. Very soothing too.
I wonder about clover sprouts...I have been growing and eating a lot of alfalfa and clover sprouts this winter.