Are nail problems ever a sign of a medical illness?
There are a lot of medical illnesses that are diagnosed through the fingernails or toenails. These include nutritional problems, such as calcium and protein deficiencies, and diseases like psoriasis, which can cause a pitted look and white discoloration.
Another problem may be lichen planus, which is basically a thickening of the skin. White spots under the nail are usually due to some kind of trauma, or injury. Sometimes you can even see a malignant melanoma, a type of skin cancer, as a black discoloration underneath a nail. However, that doesn't mean that every black discoloration is a cancer; sometimes those are just normal changes in the nail color.
What causes ingrown nails?
Ingrown nails have a number of different causes. Some people have a lot of thick skin around the nail itself, and it's hard for the nail to grow out through it. Some people have nails, particularly toenails, that become curved, almost like an old covered wagon that buckles around and pinches in. Trauma such as having the nail stepped on can also cause ingrown nails by putting pressure on the nail and forcing it to grow into the skin. This causes a cut between the side of the nail and the skin, which can become infected and irritated.
Trimming the nails poorly can cause ingrown nails. Teenagers are particularly prone to ingrown nails. It seems that teenagers who are going through a rapid growth spurt also have faster-growing nails, so they need to cut them more often.
