From The People's Pharmacy:
"A reader offered the following suggestion for getting rid of nail fungus: “I cured my toenail fungus using a 50/50 mixture of vinegar and Listerine. I combined them in a quart jar with a screw-on lid and used a clean paintbrush to apply the liquid to the affected toes morning and night. “Then I put my socks on to keep it acting a while longer and protect the bed sheets at night. The fungus took about three months to clear up. It is slow growing, but is also slow to cure. I hope this helps someone else."
The herbal ingredients in Listerine (menthol, eucalyptol, thymol and methyl salicylate) may have anti-fungal properties, but home remedies rarely come with specific guidelines. This reader combined a couple of favorite remedies. Many people have reported success soaking infected nails in one part vinegar to two parts water. Others got good results soaking their toes in Listerine. Such remedies won’t work for everyone and take several months to produce results.
Other home remedies that readers have used to treat their nail fungus include Vicks VapoRub, hydrogen peroxide, tea tree oil and cornmeal mush as a foot soak. Search this site to find more details on using home remedies against nail fungus. The comments below also contain advice that may be helpful."
Comment: The standard treatment for proven fungal nails (onychomycosis) is Lamisil 250 mg a day for 6 weeksfor finger nails and 250 mg a day for 12 weeks for toe nails. This has a 40 - 50% success rate which mayu not be all that better than with Listerine. Of course, one needs to consider the severity of the infection, and then any contraindications to the oral meds.