Amorolfine application is more effective in the treatment of mild gray nails, but has limited usefulness in the treatment of moderate and severe gray nails. The main causative agents include Trichophyton rubrum, Trichophyton spp. and Trichophyton flocculare. When the nail is invaded by the fungus, the structure and color of the nail will change, such as deformation, thickening, separation, peeling, and the nail turning yellow or black. Amorolfine application has a broad-spectrum antibacterial as well as antibacterial effect, and has a high clearance rate of fungi. It can be used as a topical treatment for nail fungal disease, penetrating into the nail crevices and treating the fungus inside them. This medicine is usually used for the less severe gray nails that do not involve the nail matrix, i.e., the area where the growth of the finger (toe) nail begins, etc., and the treatment is more effective. It is also effective in treating other infected nails, although there may be slight flaking, burning and erythema during treatment. Amorolfine application is more effective in treating distal lateral gray nails and is also suitable for patients who resist or are not suitable for systemic medication, for which the quality of life will also be improved. However, in the case of moderate and severe gray nails, the effect of using amorolfine application alone will not be too good, as the penetration of topical medication is limited, so oral antifungal medications such as terbinafine and itraconazole are also needed in combination with amorolfine application treatment. If necessary, surgical nail extraction may be required.