I have had atopic dermatitis and allergies my entire life, but what appeared on my thumb 1 year ago was a new level of gnarly. About a month ago, I finally diagnosed it as dyshidrotic eczema. Ugh!! I'm still convinced it has an invasive cause such as a fungus. This monsterous form of eczema is from hell and I guess I'm thankful it's confined to a single finger knuckle.
Similar to the hydrogen peroxide and vinegar suggestions on this thread, I've tried diluted tea tree oil. I think with extremely limited use (I got carried away and it lead to skin thickening), it dries out the blisters which I suspect is necessary to get rid of this rash. The drying effect also exacerbates cracking and itching of skin. I am going to try the vinegar now, thanks for the suggestion!
What is perhaps something like magical chapstick is SUPER SALVE made by The Super Salve Company. I picked it up by chance at a food co-op in NM because "the rash" had gotten way worse while traveling in a dry climate. Turns out Super Salve which comes in a convenient stick form has many key ingredients I have found online recommended by naturopaths: olive oil, chaparral leaf (Dr. Weil recommends making poultice of this stuff ???), comfrey leaf, echinacea flower, hops flower, usea moss, bees wax, cocoa butter, sweet almond oil, vitamin E, etc.
About 4 months ago, I had almost entirely rid myself of dyshidrotic by just applying Super Salve...until I spent a week in a pool & hot tub not knowing its impact on the rash. Need I write it came back with a vengeance?
At the time, I thought maybe the Super didn't work, that perhaps the rash cleared from something else. I began trying other things. Finally, I figured out what I was suffering from (my week of water frolicking had tanked my good effort) and went back to a steady application of Super Salve - within 2 days there was significant improvement. Yes, it does leave a green goo coating on my skin, but it works. Evidence: it heals cracks, swelling, & red irritation of the skin within hours. You can see the improvement. From my previous trial and present rate of healing, I think it will take a month for this to be 90% clear. Instead of gloves, I apply a thick layer of vaseline on my knuckle before showering. As soon as the Super is entirely absorbed by my skin, I reapply. I am going to kick this rash to the curb. You can buy the Super from super salve dot com according to the label and the "large" stick cost me $4 at the co-op.
Note: Do be careful handling clothing, the goo will leave an oil stain on fabric and I have yet to get it out of a favorite silk shirt :(. Despite that, I'm still convinced super salve is super.
Hope: I'm hoping the potent combination of Super combined with vinegar washes (as suggested), taking Borage oil supplement and probiotics will get rid of this evil for all time. 'Cause despite what experts say, I'm convinced this junk has a nasty invasive root cause and I am conducting a full assault.