Dermatology/Big Toe Nail Appearance
Hello Dr. Fisher: the big toe nail from both of my feet have this yellow fungus-like appearance but we did two fungus tests on each nail, one month apart, and both times the tests came back negative. I mean, my nails look just like the pictures on the internet for fungus presence and they give off this bad smell when wet. If it's not fungus....then what could it be? Please advice.
There can be a number of causes for yellow nails. The most common cause I see is nail polish. Below is a list of some of the causes of yellow nails.
Yellow Nail Syndrome
Yellow nail syndrome (YNS) is rare and thought to be genetic in certain cases. It is linked to lymphedema, a condition affecting the lymphatic system and causing swelling in one or more extremities. Sufferers also tend to have respiratory tract abnormalities. In addition to yellow coloring, the nails of YNS sufferers often lack a cuticle and are slow to grow. The nails can also be loose or detached from the nail bed.
YNS is most common in older adults. Individuals who believe they might have lymphedema need medical treatment for the accompanying respiratory and lymphatic system issues. The changes to the nails are often permanent, according to the New Zealand Dermatological Society. Oral medication and a vitamin E topical treatment have helped control the syndrome in some cases.
Psoriasis is a common inherited skin disorder. Its sufferers have red, irritated skin with some flaky patches or scales. Approximately half of all psoriasis sufferers will see changes in their nails, while about 10 percent of those with psoriasis experience visible changes only in the nails. If the nails are affected by psoriasis they will often thicken and display pits on the surface. They will also show yellow-brown or yellow-pink spots.
Diabetics' nails will often have a yellowish hue. This is a benign condition that is likely caused by a protein-glucose reaction in the body, suggests a study cited in the Electronic Textbook of Dermatology.
Nails may simply yellow due to the aging process. As a person grows older, his nails become more brittle. The toenails in particular harden and thicken, becoming opaque or a dull yellow.
Nail Polish Use
Using nail polish frequently without giving nails a chance to recover can lead to brittleness and discoloration. Polishes, especially red ones, can cause nails to turn yellow. To prevent color changes, always use a protective base coat before painting nails, and avoid long-term use of nail polish.