What causes thickening and yellowing of toenails?
Apr 24, 2023
Source: Cainiu Health
Dr. Liu Wan
Introduction
Thickening and yellowing of toenails may be caused by physiological factors, onychomycosis (fungal nail infection), or congenital pachyonychia, among other reasons. If toenails become thickened and discolored, it is advisable to seek medical attention promptly for accurate diagnosis and appropriate treatment. During the examination, the doctor may assess the condition of the nail plate and nail bed to further identify disease characteristics associated with different underlying causes.
Thickening and yellowing of toenails may be caused by physiological factors, onychomycosis, or congenital pachyonychia, among other reasons. Details are as follows:
1. Physiological Factors
Thickening and yellowing of toenails may also result from natural growth and aging. As people age, nails may become thicker and more prone to yellow discoloration. Changes due solely to physiological factors typically do not involve obvious symptoms in the nail bed or surrounding tissues, and nail thickness does not increase excessively—only the color changes.
2. Pathological Factors
1) Onychomycosis
Onychomycosis, also known as tinea unguium, is one of the major causes of thickened and yellowed nails. Infection often occurs through routes such as athlete's foot between the toes, wearing tight shoes, or using contaminated tools after cutting the nail cuticle. The infection usually affects one or more toenails, nail plates, and underlying nail bed tissue. Symptoms include gradual nail deformation, loss of luster, thickening and yellowing of the nail, and band-like defects at the nail edges ranging in color from white to brownish-yellow. Treatment under a doctor's guidance may include antifungal medications such as itraconazole, terbinafine, or fluconazole.
2) Congenital Pachyonychia
If an individual has congenital pachyonychia, their toenails may be naturally thick, brittle, and prone to cracking. Once cracked or peeled, they are highly susceptible to infection. This condition is often hereditary and frequently involves both fingernails and toenails. Another contributing factor is excessive body weight; prolonged pressure from bearing extra weight can soften toenails and lead to thickening over time. Topical keratolytic agents such as lactic acid lotion, salicylic acid, and urea preparations may be applied locally to help alleviate symptoms.
If toenails become thick and yellow, prompt medical evaluation is recommended to determine the underlying cause and initiate appropriate treatment. During examination, the doctor may assess the condition of the nail plate and nail bed, and may take tissue or cellular samples from beneath the nail keratin layer to further identify the specific disease characteristics causing the changes.
