The mud in the toenail especially stinks may be caused by poor hygiene, but also may be due to nail groove inflammation, nail fungus and other diseases. 1. Poor hygiene: If you don’t pay attention to foot hygiene, wear hot shoes for a long time, when a lot of sweat infiltrates the cuticle of the skin, then the mud with a foul odor will be formed. 2. Inguinitis: If it is acute inguinitis, it is mostly considered to be caused by bacterial infection secondary to minor trauma, including Staphylococcus aureus, Pseudomonas aeruginosa, etc. If it is chronic inguinitis, it will be formed when a large amount of sweat infiltrates the cuticle. If it is chronic inguinitis, it may be related to long-term exposure to irritants, Candida infection or allergens. The main manifestations of inguinitis are redness, swelling, heat and pain, and some patients’ toenails are prone to mud and odor. 3. Nail fungus: the main causative organism of this disease is dermatophytes, including red trichophyton, bearded trichophyton and so on. Common susceptibility factors include nail trauma, local lymphatic circulation disorders, and impaired immune status. Common symptoms are that the nail plate will become thickened, atrophied, cloudy, etc. When the pathogenic bacteria multiply in the stratum corneum, then the mud in the toenail will appear particularly smelly. There are many reasons why the mud in the toenail is particularly smelly, and it is necessary to go to the hospital for consultation to clarify the specific cause.