Nails covered with vertical lines may be a normal sign of physiology, such as aging. It can also be caused by certain diseases, such as onychomycosis and nail dystrophy.
In older people, the surface of the nails can be rougher and form vertical lines, which is caused by the aging of the nails.
The early signs of onychomycosis are white vertical or horizontal lines on the nails and an uneven nail surface. It is associated with fungal infection of the nail or nail bed.
When the nail is malnourished, such as a vitamin deficiency, it can lead to white spots or white vertical lines on the nail.
When it is suspected that the nails may be covered with vertical lines caused by a medical condition, it is necessary to seek medical attention and treat the condition after the cause has been clarified.