Major illness will cause a deep transverse grooves to form across the nails. Discoloration, thinning, thickening (onychogryposis), brittleness, splitting, small white spots, convex (clubbing) and concave (spooning), flatness of the nails can indicate illness in other areas of the body such as nutrient deficiencies, drug reaction, poisoning, or local injuries.

Nails may also dry out, peel, break, and get infected with fungus (onychomycosis) or degenerate (onychodystrophy).
Manicures are used to groom, trim and manage calluses with various tools such as cuticle scissors, nail scissors, nail clippers, and files.

Nail tools such as files may also spread bacteria and transmit infections if they are used on different people.

New improved contactless tools have been developed such as the gel and cream cuticle removers rather than cuticle scissors to avoid the spreading of bacteria.