I can’t really help you with “nail diseases” but I can help you from nail damage. Bite your fingernails or pick at your cuticles. These habits can damage the nail bed. Even a minor cut alongside your fingernail can allow bacteria or fungi to enter and cause an infection. Pull off hangnails. You might rip live tissue along with the hangnail. Instead, carefully clip off hangnails. Use harsh nail care products. Limit your use of nail polish remover. When using nail polish remover, opt for an acetone-free formula. Ignore problems. If you have a nail problem that doesn't seem to go away on its own or is associated with other signs and symptoms, consult your doctor or dermatologist for an evaluation