Empty nails are usually due to lack of nutrients in the body, nail fungus, nail psoriasis and other factors. 1. Lack of nutrients in the body: calcium, vitamin D and other elements necessary for the formation of nails, when the lack of these nutrients in the body, the phenomenon of empty nails can occur. And empty nails are easy to hide dirt, resulting in the emergence of odor. 2. ringworm of the nail: commonly known as gray nails, mainly due to the ringworm bacteria invade the nail plate and nail lesions caused by the nail, the patient’s sick nails can appear cloudy, separation, atrophy, warping and other phenomena, resulting in nails inside the empty, if the secondary infection, there can be a foul smell. 3. Nail psoriasis: the nail surface lesions caused by psoriasis invading the nail bed or nail matrix, the patient’s sick nails may appear under the nail thickening, nail peeling, lobe bleeding and other phenomena, if there is inflammation, it may be accompanied by foul smell. There may be other reasons why the nails are empty and smelly inside, so it is recommended to go to the hospital in time to find out the cause of the disease and receive treatment as soon as possible.