- Fungal infections can cause fingernails to have a yellowish, crumbly appearance. According to the Mayo Clinic, elderly people are more likely to develop nail fungus. Several types of fungi can cause a fungal nail infection, including yeast and mold. Fingernails are less likely than toenails to develop a fungal infection, but fingernails are prone to fungal infection as well.
- A bacterial infection of the nail bed is called paronychia. Paronychia occurs when bacteria infects a very small cut or scrape around the fingernail. According to the National Institutes of Health, paronychia can occur at any time, although people whose hands are frequently wet or damp are more likely to develop this type of infection. The skin on the sides of the nail will often be red and inflamed and may ooze pus and blood.
- According to the American Academy of Dermatology, about 50 percent of people who have psoriasis will also experience psoriatic changes to their fingernails. These changes can appear as deep pits, yellowed, crumbling edges or a yellowish pink color to the fingernail. In cases where the nail bed has been affected by psoriasis, the fingernail may also fall off or cease to grow.
- Onycholysis occurs when the nail separates from the nail bed over time. It is a painless process and can result in the nail falling completely off. In other cases, it will lift from the nail bed like a car trunk or hood. This condition can be a result of injury to the nail, infection, or it can be a sign of a non-nail related condition such as anemia.
- According to the American Osteopathic College of Dermatology, brittle fingernails are more common in women than in men. It is most often caused by repeated exposure to water and repeated drying, but can also be caused by over-buffing. Brittle nails will often flake and split, which can lead to infections in the nail bed. Wearing waterproof gloves when hands are exposed to water can help prevent brittle fingernails from developing.