I am 63 years old. I have had this on my right big toe and a bit on my left for many many years, since my late 40s. FINALLY I found Dr. Scholls brand topical treatment (they keep it behind the counter at Boots with the Curanail). For some reason they only put their own Boots brand out on the aisle display. It's not cheap but it does last if you use it properly.
It's the only topical one that has worked for me.I tried Vicks, Tea Tree Oil, Listerine, Oregano and Wild Thyme oil. Nothing! Dr Scholls comes with a set of rough nail files that are disposable so you can grind down the surface as you apply the clear liquid with a brush (like nail varnish bottle). Those pesky pen jobs are rubbish as you can't really get under the nail!
After a few weeks of following those instructions about filing the nailbed, you just keep applying the clear liquid daily which dries in 5 mins before putting on footwear. PERSONALLY, I am doing it twice a day, morning and night. Also change your socks/tights EVERY DAY. Don't wear the same shoes every single day. I also use Dr S's athletes' foot powder spray inside my shoes and I use their cracked heel balm. All of these have made a big difference.
It's been 5 months for the toenaisl and after that first month I noticed that when I would clean under the nail of the worst one, that nasty white gunk became powdery and now I don't get any stuff when I scrap under the nails. The toe that wasn't very bad had almost grown out, but because my feet are always next to each other, eg under bedclothes, etc. I am continuing to treat both toes.
I don't grind the tops down now as I don't want to lose the top nailbed (eg have it crumble off from being too thin) and have only a fresh tender first layer underneath...am afraid of getting ingrown nails as the new ones grow out which would hurt when it's still boot and trainer weather. So I just keep trimming straight across the top with clippers, then file the edge smooth with a regular nail file. When it goes, it goes. I might consider those gel nail tubes when that happens.
Hope this helps. I signed on today because it's been so frustrating. My sis in law who has diabetes had this a few years back and her chirod just yanked the nail off! It didn't hurt, but it was summer and she could wear sandals till her new nail grew out. It's too cold for that for me!
PS if your bedmate has it, you both have to be treated. My husband got rid of his first. He'd had it since rugby playing days where toenails got trod and stomped on. Our doctor was going to give us the pills, but we decided to try this insteat. So far...so good. I think in another 3 months the worst toe, the right one, will be finally grown out!
Cheers, Lew