Thick toenails may be related to congenital development, age, gray nails, psoriasis and other factors. 1. Congenital developmental abnormality: usually chromosomal dominant inheritance, which is a hereditary disease. 2. Age: under normal circumstances, with age, the body’s metabolism will gradually slow down, resulting in the accumulation of cuticle in the nails, which leads to the phenomenon of thick toenails. 3. Gray nails: usually caused by fungal infections, its clinical symptoms are thickening of the nail surface, shedding, discoloration and so on. 4. Psoriasis: usually due to genetic, environmental and other factors caused by the skin disease, the onset of the initial period, the patient will appear red papules or maculopapular phenomenon, if not treated in time, may lead to local coverage of thick layer of silver-white scales, thus appearing toenail thick phenomenon. Toenail thick, no other uncomfortable symptoms, generally do not need special treatment, if there is pain and other symptoms, it is recommended to seek medical treatment in a timely manner, under the guidance of a professional doctor to standardize the treatment and use of medication, so as to avoid delays in the condition.