The whitening is the corrosive effect of the corneal layer cells by the corneal patch. The main component of the corneal patch is salicylic acid, which is highly acidic, and the corneal layer cells will turn white when corroded by strong acid. In addition, too much time on the patch will also be white, because the cells of the stratum corneum will also be white after absorbing more water. There is no need to be overly nervous about whitening. If there is only a slight whitening after the application of corns, without any uncomfortable reaction, it may be that the application of corns is not long enough. If there is a slight pain, it means that the time of using the ointment has reached the standard. At this point, you can tear off the ointment and remove as much of the whitened cuticle as possible. If the skin underneath is relatively normal and there is no pain when you press your fingers after removing it, it means that the degree of application is just right. If there is pain after the whitish cuticle is removed, it means that the corns are not applied for long enough and can be repeatedly applied. If the pain is severe, it is too long to paste.