I have had plaque psoriasis since the age of thirteen (I’m now 54), which has grown much more extensive in recent years.
The nail on the second toe of each of my feet had become thickened, and very difficult to trim, even after lengthy soaking. One doctor said “it’s psoriasis,” while another said “it’s a fungal infection.”
It probably was a combination, because I am also diabetic, and yeasts and fungi just love diabetics, although the treatments the doctors recommended did not work in any case.
Then because I’d heard of so many uses for 3% hydrogen peroxide, I bought a quart (for less than $2) and used it, straight out of the bottle, as a foot soak before my pedicure.
I used it at room temperature and let my feet soak for 30 minutes. After two or three months of doing this once every week or so, my nails were flat and almost normal.
I’m told this also works well against athlete’s foot.