Nail Diseases and Disorders Glossary

Nail disorders comprise about 10 percent of all skin conditions. Due to their location, nails take a lot of abuse, and most minor nail injuries heal on their own. More serious injuries or disorders require professional treatment. Symptoms that could signal nail problems include:

  • Pain
  • Color changes
  • Shape changes
  • Swelling of the skin around the nails
  • Persistence of white or black lines
  • Dents or ridges in the nail

While the above symptoms may or may not represent a nail disease or disorder, nail technicians should recommend to their clients to report them to their doctor or a dermatologist to be checked out. The nails can reveal much about a person's overall health. Many diseases and serious conditions can be detected by changes in the nails. The most common health conditions and their effect on the nails are:

Condition Appearance
Anemia Pale nail beds
Diabetes Pale nail beds
Heart Conditions Pale nail beds
Kidney Diseases Half and half nails: ½ pink & ½ white
Liver Diseases White nails
Lung Diseases Yellowing and thickening of nail, and slowed growth rate

Common Nail Diseases and Disorders

Aging nail problems usually increase throughout life and affect a high number of the elderly. This is due to the susceptibility of the nail to fungal infections, its increased thickness with age, circulation problems, and the use of medications.

Bacterial Infections cause redness, swelling, and pain of the nail skin folds. The most common cause is trauma to the nail or surrounding skin, as well as frequent exposure to water and chemicals. A green discoloration of the nail is due to infection by a bacterium called pseudomonas.

Beau's Lines:

Are characterized by vertical splitting or separation of the nail plate layers at the distal (free) edge of the nail plate. In most cases, nail splitting and vertical ridges are characteristic of the natural aging process. This nail problem is also the result of overexposure to water and household cleaning solutions. As we age, the nail bed's natural flow of oils and moisture is greatly reduced. This oil and moisture is the cement that holds the nail plate layers together and gives the plate its inherent flexibility. Salon moisturizing treatments such as oils and paraffin wax are recommended.

Dark spots in the nail must be examined by a dermatologist to be certain they are not cancerous.

Fungal Infections often cause the end of the nail plate to separate from the nail bed. Debris (white, green, yellow, or black) may build up under the nail plate and discolor the nail bed. The top of the nail or the skin at the base of the nail can also be affected. Toenails are more susceptible to fungal infections because they are confined in a warm, moist environment. These make up approximately 50 percent of all nail disorders and can be difficult to treat. Candida or yeast infections are common in fingernails, especially if the hands are always in water or if the person has diabetes.

A Hematoma:

Is the result of trauma to the nail plate. Causes include slamming a finger or toe in the car door, friction from improperly fitting shoes, or a sports related injury. The nail bed will bleed due to this trauma, and the blood is trapped between the nail bed and the nail plate. A hematoma may also indicate a fractured bone. Hematomas may result in nail plate separation and infection because the blood can attract fungi and bacteria.

Ingrown Nails form at the corner of the nail that curves downward into the skin. The great toenails are particularly vulnerable. Improper nail trimming, tight shoes, or a poor stance can all lead to this common nail problem. Ingrown nails can be painful and sometimes lead to infection. Proper treatment can avoid problems.


Is usually caused through iron deficiency anemia. These nails show raised ridges and are thin and concave. Seek a physician’s advice and treatment.


Is evident as white lines or spots in the nail plate and may be caused by tiny bubbles of air that are trapped in the nail plate layers due to trauma. This condition may be hereditary and no treatment is required, as the spots will grow out with the nail plate.


Are vertical pigmented bands, often described as nail 'moles', which usually form in the nail matrix. Seek a physician’s care should you suddenly see this change in the nail plate. It could signify a malignant melanoma or lesion. Dark streaks may be a normal occurrence in dark-skinned individuals, and are fairly common.

Mucinous Cysts:

Are clear, jelly-filled papules that can appear at the base of the nail. They can become painful, may damage or deform the nail, and should be removed.

Nail Biting:

Is a common problem, especially among young children. While the habit is typically outgrown, it has been linked to anxiety or boredom in older children and adults. Not only does nail biting ruin the look of the nails, it is also a good way to transfer infectious organisms from the fingers to the mouth and vice versa. A tic habit deforms the nails by repeated picking at the cuticle.


Is an atrophy or wasting away of the nail plate which causes it to lose its luster, become smaller, and sometimes shed entirely. Injury or disease may account for this irregularity.


Is evidenced by over-thickening of the nail plate and may be the result of internal disorders.


Are claw-type nails that are characterized by a thickened nail plate and are often the result of trauma. This type of nail plate will curve inward, pinching the nail bed and sometimes require surgical intervention to relieve the pain.


Is the term used to describe nail plate separation from the nail bed. This condition can be caused by mechanical force (trauma that tears the nail plate from the bed) or by infection (fungal or otherwise). Onycholysis is not a “disease” per se, but rather a symptom of a disease or disorder. It is often seen in the condition onychomycosis (see below).


Is the medical term for the condition resulting from a fungal or yeast infection. It is a common condition affecting almost 3% of the population. Dermatophytes (a type of fungus) are by far the most common cause, and the toenails are affected in 80% of cases. A fungal or yeast infection, which results in Onychomycosis, can invade through a tear in the proximal and lateral nail folds as well as the eponychium. This type of infection is characterized by onycholysis (nail plate separation) with evident debris under the nail plate. It normally appears white or yellowish in color, and may also change the texture and shape of the nail. The fungus digests the keratin protein of which the nail plate is comprised. As the infection progresses, organic debris accumulates under the nail plate often discoloring it. Other infectious organisms may be involved, and if left untreated, the nail plate may separate from the nail bed and crumble off.


Is the term for brittle nails, which often split vertically, peel and/or have vertical ridges. This irregularity can be the result of heredity, the use of strong solvents in the workplace or the home, including household cleaning solutions. Although oil or paraffin treatments will re-hydrate the nail plate, one may wish to confer with a physician to rule out disease.

Paronychia infections of the nail fold can be caused by bacteria, fungus and some viruses. The proximal and lateral nail folds act as a barrier, or seal, between the nail plate and the surrounding tissue. If a tear or a break occurs in this seal, the bacterium can easily enter. This type of infection is characterized by pain, redness and swelling of the nail folds. People who have their hands in water for extended periods may develop this condition, and it is highly contagious.


Is often due to dryness. This causes the nail layers to separate. Peeling can also be caused by improper or aggressive filing, which can cause trauma to the natural nail.

Pseudomonas bacterial infection can occur between the natural nail plate and the nail bed, and/or between an artificial nail coating and the natural nail plate. Many people have been led to believe that the classic 'green' discoloration of this type of infection is some type of mold. In actuality, mold is not a human pathogen. The discoloration is simply a by-product of the infection and is caused primarily by iron compounds.

Pseudomonas thrives in moist places; it feeds off the dead tissue and bacteria in the nail plate, while the moisture levels allow it to grow. The after effects of this infection will cause the nail plate to darken and soften underneath an artificial coating. The darker the discoloration, the deeper into the nail plate layers the bacteria have traveled. If the bacteria have entered between the nail plate and the nail bed, it will cause the same discolorations and may also cause the nail plate to lift from the nail bed.


Is a chronic skin disease characterized by red, scaly patches. Approximately 10 to 50 percent of people with psoriasis, and 80 percent of people who suffer from inflammation associated with psoriasis, have nail problems, especially affecting the fingernails. The most common signs include pitting, rippling, or discoloration of the nail, reddish-brown discoloration of the skin under the nail, separation of the nail from the nail bed, splinter hemorrhages, crumbling and/or splitting of thenail, as well as swelling and redness of the skin surrounding the base of the nail. Psoriasis is not contagious. Do not attempt salon treatments on a client with Nail Psoriasis. The client should consult with a dermatologist for diagnosis and treatment.


Is the inward advance of skin over the nail plate, usually the result of trauma to the matrix due to a surgical procedure or by a deep cut to the nail plate. Pterygium results in the loss of the nail plate due to the development of scar tissue. Cortisone is used to prevent the advancement of scar tissue. Never attempt to remove Pterygium; consult a physician for advice and treatment.

Pterygium Inversum Unguis:

Is an acquired condition characterized by a forward growth of the hyponychium. This live tissue firmly attaches to the underside of the nail plate, which contains a blood supply and nerves, and grows out with the nail. Possible causes are systemic, hereditary, or from an allergic reaction to acrylics or solvents. Never use force to 'push back' the advancing hyponychium, as this will result in a bleeding and pain for the client. Consult a physician for diagnosis and treatment.

Splinter Hemorrhages:

Are a disruption of blood vessels in the nail bed that can cause fine, splinter-like vertical lines to appear under the nail plate. They are caused by trauma to the nail or by certain drugs and diseases.

Tinea Unguis, or ringworm of the nails, is characterized by nail thickening, deformity, and eventually results in nail plate loss.

Tumors can be found in any portion of the nail. The nail plate could change shape or be destroyed due to interference of a growing tumor. If the tumor extends into the nail folds or is located under the nail plate, surgery may be necessary to remove it. Sometimes during the treatment of a tumor, the nail can be further damaged.

Vertical Ridges:

Are usually characteristic of aging, although they are not limited to the aged or elderly. The nail plate grows forward on the nail bed in a 'rail and groove' effect, much like a train rides on its' tracks. As we age, the natural oil and moisture levels decline in the nail plate, and this rail and groove effect becomes apparent resulting in ridged nails. This condition improves with re-hydration of the nail through salon moisturizing treatments.


Are viral infections that affect the skin surrounding or underneath the nail. They can be painful and sometimes cause limited use of the affected finger or toe. Treatment usually involves freezing or chemicals that destroy the wart. If the wart extends into the nail folds or is located under the nail plate, surgery may be necessary to remove it.

White Spots:

Are small, semi-circular spots that result from injury to the base (matrix) of the nail where nail cells are produced. They are not a cause for concern and will eventually grow out. White spots are very common and usually recur.

Yellow Nails:

Are usually caused by stains and are harmless. Commonly it is caused by dark colored nail polishes, especially when used without a quality base coat. The nails can also pick up stains from everyday things handled by the client, such as food, household chemicals, paint, and even fabric. A fine white buffer can usually remove the stain, however, aggressive buffing is to be avoided as it may thin the nail, causing true damage.

Nail disorders:

Are difficult to treat and respond very slowly to therapy due to the slow growth rate of the nail and its inability to absorb medications very well. Surgical treatment is common to remove tumors or correct structural abnormalities. Non-surgical treatments include the use of topical or oral medications.