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This guide will assist cosmetology students with techniques, styles, fundamentals, and foundations of hair, skin, face, and nail care.

Nail Disorders & Diseases

Nail Disorders & Diseases

Nail disorder is a Condition caused by injury, herdity, or previous disease of the nail unit.

Common Nail disorders

Common Nail Disorders

Beau's lines: are deep grooved lines that run from side to side on the fingernail or the toenail. They may look like indentations or ridges in the nail plate.

Blue fingernails: are caused by a low level or lack of oxygen circulating in your red blood cells. This condition is known as cyanosis. It occurs when there isn't enough oxygen in your blood, making the skin or membrane below the skin turn a purplish-blue color.

Bruised nail beds or Subungual hematoma:  the medical term for bleeding and bruising under the nail. This is usually the result of some kind of injury to the blood vessels under the nail bed.

discolored nails: the nails appear white, yellow, or green, and can result from different infections and conditions of the skin

Eggshell nails: A condition of your nails that causes them to appear thin, white, and brittle like that of an eggshell

Hangnail: a tiny, torn piece of skin, more specifically eponychium or paronychium, next to a fingernail or toenail. Hangnails are typically caused by having dry skin, or by trauma to the fingers, such as paper cuts or nail biting

Koilonychia: also known as spoon nails, is a nail disease that can be a sign of hypochromic anemia, especially iron-deficiency anemia. It refers to abnormally thin nails (usually of the hand) which have lost their convexity, becoming flat or even concave in shape.

Leukonychia spots: a condition where white lines or dots appear on your finger or toenails. This is a very common issue and entirely harmless.

Melanonychia: a condition of either the fingernails or the toenails.  Melanonychia is when you have brown or black lines on your nails. The decolorization is usually in a stripe that starts at the bottom of your nail bed and continues to the top. It may be in one nail or several.

Onychophagy: an oral compulsive habit of biting one's fingernails

Onychorrhexis: a brittleness with breakage of finger or toenails that may result from hypothyroidism, anemia, anorexia nervosa or bulimia, or after oral retinoid therapy

Plicatured nail: a type of highly curved nail plate often caused by injury to the matrix, but may be inherited;also called "folded nail"

Ridges: Vertical lines running the length of the natural nail plate, usually related to normal aging

Splinter Hemorrhage: tiny blood spots that appear underneath the nail. They look like splinters and occur when tiny blood vessels (capillaries) along the nail bed are damaged and burst. 

Uncommon Nail Disorders

Uncommon Nail disorders


Onychauxis: a nail disorder that causes fingernails or toenails to grow abnormally thick. Over time, the nails may become curled and turn white or yellow.

Onychogryposis: a nail disease that causes one side of the nail to grow faster than the other. The nickname for this disease is ram’s horn nails because the nails are thick and curvy, like horns or claws.

Nail Pterygium: a disorder characterized by an overgrowth of the proximal nail fold onto the nail bed.

Pincer nail: a condition characterized by excessive transverse nail curvature, progressively pinching the nail bed distally.

Infectious Nail Diseases

Infectious Nail Diseases


Onychia: an inflammation of the nail folds (surrounding tissue of the nail plate) of the nail with formation of pus and shedding of the nail. Onychia results from the introduction of microscopic pathogens through small wounds.

Onychomycosis: a fungal infection of the nails that causes discoloration, thickening, and separation from the nail bed. Onychomycosis occurs in 10% of the general population, 20% of persons older than 60 years, and 50% of those older than 70 years.

Paronychia: an infection of the skin around your fingernails and toenails. Bacteria or a type of yeast called Candida typically cause this infection. redness, pus, and swelling are usually seen in the skin fold adjacent to the nail plate.

Pseudomonas aeruginosa: common bacteria that can lead to bacterial infection that appears as a green, yellow, or black discoloration on the nail bed

Pyogenic granuloma: severe inflammation of the nail in which a lump of red tissue grows up from the nail bed to the nail plate.

Tinea pedis: also known as athlete's foot; red, itchy rash on the skin on the bottom of feet and or between toes.

Noninfectious Nail Diseases

Noninfectious Nail Diseases


Nail Psoriasis: a noninfectious condition that affects the surface of the natural nail plate causing tiny pits or severe roughness on the surface of the nail plate.

Onychocryptosis: also known as ingrown nails; nail grows into the sides of the tissue around the nail.

Onycholysis: lifting of the nail plate from the nail bed without shedding, usually beginning at the free edge and continuing toward the lunula area

Onychomadesis: the seperation and falling off of a nail plate from the nail bed; affects fingernails and toenails