About ten years ago, I had a nail fungus that had existed for about three years. I tried a number of the over the counter solutions and none of them worked. I talked to the pharmacist and keep in mind this was ten years ago and I don't know what's available now. At that time, the pharmacist said that there were pills but that they were only marginally effective, if at all, and there was considerable risk in taking these pills.
So, I started considering other ways I might get medication below the nail to treat it. At one point I even considered drilling a hole through the nail to try and introduce some kind of medication.
Then, having made wine for years, I was aware that if the primary fer-mentor became too warm/hot that the yeast would die in what's called a 'struck' fermentation. When that happens the must needs to be cooled down and new yeast needs to be introduced, to restart the fermentation.
I wondered, if heat can kill yeast, perhaps it could also kill fungus. So, here's what I did.
I took a piece of congregated cardboard about six inches square and made a hole about a half inch in diameter in the centre. For those using metric, this would be about 15 cm and the hole would be about 1.3 cm. If you are treating multiple nails you should consider making multiple templates with different size centre holes commensurate with the size of the nail to be treated. The hole should always be smaller than the size of the nail being treated. The purpose of the cardboard is to protect the skin surrounding the nail, so that only the nail receives the treatment. One further thing I needed was a handheld electric hairdryer.
Treatment: So, each morning after I had my shower, I would hold the cardboard over the nail that needed treatment, and direct the heat of the hair dryer through to hole in the cardboard to treat the nail underneath until I felt a minor pinch. I would then wait about twenty seconds or so for it to cool down, and then do this two more times. I originally intended to do this for seven days, but in the end, just to be sure, I did this for a total of ten days.
I then just allowed the nail to grow out. The nail grew back and there was no more fungus. That was ten years ago and the fungus has not returned.
I hope this is of help to anyone out there that's needing this solution.