Vertical or lengthwise ridges in the nail extending from the cuticle to the tip are primarily attributed to aging, but they also can result from trauma or an underlying medical condition, according to MedicineNet. These lines are a fairly common phenomenon caused by the nail not retaining as much moisture as it ages, according to Huffington Post.
The vertical ridges on nails result from the nail becoming atrophied in certain areas, explains Huffington Post. Ridges of this nature that are evenly spaced over the entire nail are fairly common and are generally not a cause for medical concern. Rather than buffing the nail, which can cause the ridges to split, the best way to treat the lines is by using a thick lotion or petroleum jelly on the nails to moisturize them, applying several times a day.
In contrast, horizontal lines, ridges or depressions in the nail, also knows as Beau's lines, can be cause for concern. Recurring horizontal lines could point to a chronic underlying medical condition, including severe infections, vascular disease or diabetes, warns MedicineNet. Nail discoloration is another sign of an underlying condition that should be assessed by a dermatologist or other medical professional, notes the Mayo Clinic.