How to identify the real grey nail from the many fake grey nails? There are three points: 1. Gray nails are infectious, so they usually start with a single toenail, and the number of diseased nails increases slowly, and one or two toenails may be involved for several months or even years; however, nail dystrophy and nail stasis may cause multiple diseased nails to appear in a short period of time. 2. If left untreated, gray nails will gradually increase in size; however, nail dystrophy and nail stasis may get better on their own or repeatedly. 3. Grey nails are fungal infections, so the fungal test is positive (of course, there are sometimes false negative results), but if you have nail dystrophy and subluxation, it is definitely negative. In conclusion, a deformed toenail is not necessarily a gray nail, so don’t judge for yourself by taking random oral antifungal medication. If you can’t figure it out, get a dermatologist to take a look and do a fungal test to confirm.