★★★★★
I'm going to add my tuppence here. The nail and the skin directly underneath it are so pressed together that it is impossible for cream or liquid to get at it. Any remedy should be loaded to the sides and tip of the nail and left to the air for 20 - 30 minutes so that it can spread skin cell to skin cell for effectiveness.
I know someone who tried many things for this but would put socks and shoes on straight away so that the liquids would soak straight into the wool. A clever nurse told her to do it half an hour before she got into bed and, hey presto, faster results.