Onychomycosis is the most common infection that results in changes of color and integrity of the toenails. It is most often a secondary infection of a dermatophyte called Trichophyton rubrum. If conditions are favorable, it will often grow under the nail plate and create changes (thickening, peeling, yellowing and texture change) in a portion or the entirety of the nail.
Although onychomycosis is often a cosmetic concern, it can become painful and be the source of more serious bacterial infection.
Predispositions to such infections are aging, diabetes, decreased circulation and a weak immune system. To avoid infections, it is important to change your stockings when they are wet and to avoid the use of unsterilized instruments (used in some aesthetic institutions) or those of a family member. See your podiatrist to obtain a precise diagnosis and to assess treatment options.
Trauma or repeated microtrauma may also be responsible for significant nail changes that appear similar to onychomycosis. Sometimes trauma to the nail matrix can cause a permanent abnormal growth of the nail.
The integrity of the nail can also be influenced by the presence of systemic diseases such as psoriasis, eczema, lichen planus, lung diseases and several others.