Gray nails generally refers to onychomycosis, thick nails in old age is not necessarily onychomycosis, may be due to congenital heredity, is a normal phenomenon. When the physiological factors are excluded, it can be considered to be caused by nail fungus, psoriasis and other diseases. You can’t judge a person’s tinea cruris simply on the basis of the symptom of thick nails. If the nails are congenitally thick and there are no physical symptoms, it is considered a normal phenomenon. However, if the nails change abnormally, it is necessary to consider that it is caused by the disease. Early symptoms of onychomycosis are mostly limited nail color changes, which can be white, yellow or dirty, and nails can become brittle and easy to separate. When the nail plate is thickened or damaged, it can induce onychomycosis, with symptoms such as redness, swelling, heat and pain. Patients with psoriasis may experience symptoms such as cloudy and thickened nails when the nail is involved, suggesting an aggravation of the disease. There are many reasons that lead to thick nails, and it is recommended that patients go to regular hospitals and undergo relevant examinations, so as to clarify the causes of the disease. Once diagnosed, patients should actively cooperate with doctors to take relevant treatment measures.