Various disorders can affect the fingernails and toenails. In addition to injuries, ingrown nails and fungal and bacterial infections are common nail disorders that may require treatment. Abnormal-appearing nails are sometimes signs of underlying health problems.
Low oxygen levels in red blood cells can cause blue nails. This condition is called Cyanosis. This happens when your blood doesn’t have enough oxygen, causing the skin and membrane below it to turn a purplish-blue color.
A high level of abnormal hemoglobin could cause skin discoloration. Hemoglobin, the protein responsible to transport oxygen in your blood, is also known as hemoglobin.
Your fingernails can turn blue when exposed to cold temperatures. Because cold temperatures cause blood vessels to contract. Because of the narrow paths, it is difficult to get enough oxygen-rich blood to your nails.
Normal nail color will return to normal after massaging your hands or warming up. This is likely because your body doesn’t have enough blood supply due to cold temperatures.
The body’s normal response to cold temperatures is to produce blue fingers.
If your fingernails are still blue, it could be a sign of an underlying condition or structural abnormality that is preventing the body from delivering oxygenated red blood.
Nail disorders account for approximately 10% of all dermatologic conditions. The incidence of nail disorders tends to increase with age and with certain chronic diseases. Thus, nail disorders affect more significant numbers of older adults.
The nail plate consists of layers of hardened keratin protein—the same protein that makes up skin and hair. The plate protects the more delicate tissues of the fingers and toes. The cuticle is the horny or dead skin layer at the base and sides of the nail.
The nail bed is the skin below the nail plate. Nails grow from the bottom of the nail under the cuticle at rates that depend on heredity, activity levels, age, and health status. Nails grow faster during the summer than they do in winter. Women’s nails grow slower than men’s except possibly during pregnancy.
Fingernails, especially those on the dominant hand, grow faster than toenails: fingernails grow an average of 0.14 in. (3.5 mm) per month; toenails grow an average of 0.06 in. (1.6 mm) per month. Nails can reflect overall health since their growth and appearance are affected by nutrition, fever, diseases, chronic illness, trauma, and aging.
Healthy nails are usually smooth with consistent color and are free of spots and discoloration. Certain types of nail discoloration, thickening, or changes in growth rate can be signs of lung, heart, kidney, liver diseases, or diabetes.
Nails that are rounded inward (concavity) instead of outward can indicate iron-deficiency anemia. Pitting or thickening can be caused by psoriasis. White spots and vertical ridges on nails are harmless, but steep ridges may become more prominent with age.
Common nail disorders include:
- Ingrown toenails—in which the corner or side of a nail grows down into the soft skin instead of straight out—is the most common nail disorder.
- Onychomycosis—a fungal infection in or around a nail, especially a toenail—accounts for about half of all nail disorders.
- Paronychia—a bacterial or fungal infection of the skin adjacent to a nail—is also common.
- Injuries can affect the nail plate, bed, cuticle, and skin around the nail and increase susceptibility to other nail disorders.
Nail disorders can affect the color, thickness, texture, or shape of the nails, including the following:
- onychauxis or abnormal thickening of the nail
- koilonychias—thin, concave fingernails
- Beau’s lines—horizontal depressions across fingernails
- pitting or small depressions on the nail surface
- ridges or tiny raised horizontal or vertical lines on the nail
- onychoschizia—brittle or splitting nails
- loose or crumbling nails
- onycholysis or nail lifting—the painless separation of the plate from the bed
Risk factors for nail disorders include:
- poor nail care
- ill-fitting shoes
- frequently wet hands or feet
- advanced age
- poor circulation
The anatomy of the human fingernail. Nail disorders are most commonly caused by trauma, infections, exposure to hot water and harsh detergents, and other irritants.
Certain people are at particular risk for nail disorders:
- Onycholysis is a common problem in women with long fingernails.
- People particularly susceptible to onychomycosis include older adults; those with chronic diseases such as diabetes, circulatory disorders, or immune deficiencies; and people taking chemotherapy drugs, corticosteroids, or other medications that weaken the immune system.
- People whose hands are repeatedly submerged in water—such as dishwashers, cooks, and healthcare workers—and people with diabetes are at particular risk for paronychia and green-nail syndrome (GNS).
- Athletes such as ice skaters, ballet dancers, and long-distance runners are at risk for onychauxis and nail deformities caused by chronic trauma.
- Gardeners, janitors, and plumbers are at risk for onycholysis from nail injuries.
CAUSES AND SYMPTOMS
The most common causes of ingrown toenails are improperly trimmed nails, and ill-fitting shoes that crowd or put pressure on the toes.
Toenails clipped too short or with rounded edges instead of being cut straight across can cause a nail to grow inward. Poor eyesight, difficulty reaching the toes, or thick nails can make proper trimming difficult.
Ingrown toenails can also result from nails that naturally curve and grow downward or are too large for the toes and from foot or toe deformities that place extra pressure on a toe.
Poor stance repeated foot trauma from everyday activities, toe-stubbing or another injury, and picking or tearing at the corner of a nail can lead to ingrown toenails. Although any toenail can become ingrown, the big toe is most often affected.
Signs and symptoms of an ingrown toenail include redness, swelling, irritation, pain, and possibly paronychia.
Onychomycosis is more common in people who sweat excessively, have frequently damp skin, wear shoes that block air circulation, or have nail-bed injuries or other nail disorders.
Fungal infections of the toenails are more predominant than fingernail infections because shoes encase the toes within a warm, moist, weight-bearing environment. The toes also are more likely to be exposed to damp conditions such as locker rooms, showers, and swimming pools.
Although various yeast and other fungi typically live within the dead tissues of the nails, skin, and hair, onychomycosis often begins with a fungal infection on the foot, such as the athlete’s foot, that remains under the surface of a nail after treatment.
Onychomycosis is frequently ignored because it can persist for years without causing pain. However, the infection may spread to other nails and the skin and eventually interfere with daily activities and even walking.
Onychomycosis is characterized by progressive changes in the color, texture, and shape of the nail, including the following:
Fungal nail infection, called onychomycosis, on the discolored thumb of a female patient. Nail disorders are caused by various fungal and bacterial infections and may also occur due to injuries. (Dr. P. Marazzi/Science Source)(Dr. P. Marazzi/Science Source)
- loss of shine or luster on the nail surface
- white discoloration of the outermost layer of the toenail
- darkening of the nail
- white or yellow streaks on the side of the nail
- foul smell
- debris trapped under the nail
- crumbling of the outside edges of the nail
- loosening or rising of the nail from its bed (onycholysis)
Paronychia can be caused by Candida yeast or other fungi or by bacteria. Onychomycosis is sometimes accompanied by a secondary yeast or bacterial infection.
Paronychia usually results from poor hygiene or injury, such as biting or picking at a nail or hangnail, trimming or pushing back a cuticle, or finger sucking. Bacterial infections cause sudden symptoms, whereas fungal infections tend to develop gradually.
Paronychia is characterized by a red, swollen, painful area around the nail, usually at the injury site.
Other signs and symptoms may include:
- pus-filled blisters, mainly with bacterial infections
- changes in nail color or shape, or detachment of the nail
- red streaks along the skin
- fever and chills
- muscle and joint pain
- general malaise
GNS or chloronychia is caused by Pseudomonas aeruginosa, which lives in moist environments such as sponges, sinks, and hot tubs. P. aeruginosa produces green pigments that cause bluish-grey to dark-green discoloration under the nail.
GNS usually affects only one or two fingernails or toenails and is not painful, although the skin around the nail and cuticle can be red, swollen, and tender. Onycholysis is a significant risk factor for GNS because it breaks the waterproof seal between the skin and nail, creating space for dirt, debris, and bacteria to collect.
Onychomycosis, psoriasis, and tight-fitting shoes, especially athletic shoes, are also associated with GNS.
Nail injuries include cut, torn, bruised, and smashed nails and onycholysis. Trauma to the area below the nail contributes to onycholysis. Signs and symptoms of nail injuries include:
- cuts or tears to a nail, cuticle, or skin around a nail
- white streaks or spots on a nail—called leukonychia— that slowly grow out with average growth of the nail
- small areas of bleeding under a nail called splinter hemorrhages
- subungual hematoma—blood and fluid under a nail that can cause it to blacken
- avulsion—the partial or complete pulling away of a nail from its bed
- a crushed base of the nail or nail bed that may lead to permanent deformity
- throbbing pain
Nail abnormalities while lines within a toenail can be caused by recurring trauma, such as running too-small shoes. White lines in nails can also signify illness or trauma elsewhere in the body that causes the protein to be deposited in the nail bed.
These contrast to the usual white area at the nail fold—the lunula at the bottom of the nail—which varies in size with the individual.
Splinter hemorrhages are thin vertical lines of red to reddish-brown blood running in the direction of nail growth. They can be caused by injury or tiny clots (microemboli) in the small capillaries under the nails. They also can be signs of heart-valve infection (bacterial endocarditis) or blood-vessel damage from swelling (vasculitis).
Other nail abnormalities and their causes include:
- thickening of both the nail plate and bed from excessive buildup of keratin, which can be due to normal aging, poorly fitting shoes, trauma, onychomycosis, psoriasis, yellow-nail syndrome (YNS), hypothyroidism, or loss of a toenail that causes the new nail to grow back thicker
- brittle nails that can be a typical sign of aging or can be caused by certain diseases and conditions
- brittle and peeling nails from long-term exposure to moisture or nail polish
- Beau’s lines—temporary grooves or ridges in the nail plate following a severe illness or surgery or resulting from injury, eczema around the nail, cancer chemotherapy, or inadequate nutrition
- lengthwise split or ridged thumbnails from chronic picking or rubbing of the skin behind the nail
- pitting or splitting of the nail plate off the nail bed, chronic nail-plate destruction, or onycholysis, which can all be caused by psoriasis
- pitting from alopecia areata, an autoimmune disease that causes hair loss on the scalp and body
- ingrown skin under a nail or changes in nail shape from warts caused by viruses under the nail
- brittle nails or onycholysis from thyroid disease
- deformities called clubbing that affects the nails and areas under and around the nails and is caused by heart or lung diseases that affect the amount of oxygen carried by the blood
- koilonychias—spoon-shaped or concave fingernails from iron-deficiency anemia
- white lines and horizontal ridges from arsenic poisoning
- blue nails from silver poisoning
- lifting of the nail from the bed caused by certain antibiotics
- changes in nail appearance from malnutrition, vitamin deficiencies, systemic amyloidosis, or lichen planus
- nail damage from kidney or liver disease
- abnormal nail growth from cancer chemotherapy
Abnormalities are also caused by certain rare nail disorders:
- Habit-tic deformity most often affects the thumbnail. It is caused by chronic manipulation with the adjacent fingernail. Symptoms include a central depression in the nail and transverse parallel ridging running from the nail folds to the distal edge of the nail. In severe cases, the cuticle can disappear, and the lunula can enlarge.
- Melanoma, the deadliest sort of skin cancer, can occur under a nail (subungual melanoma). It appears as a dark streak within the nail plate that does not gradually disappear or increase over time. A darkening of the cuticle associated with the dark line—called Hutchinson’s sign—can indicate an aggressive melanoma.
- YNS has been associated with lung disease and lymphedema (swollen lymph nodes). Patients often have coexisting nail fungus.
- Nail-patella syndrome is a rare genetic disorder due to inherited or spontaneous mutations in the LMX1B gene that encodes a transcription factor for regulating the expression of other genes and is particularly important during embryonic development. With this disorder, the nails, especially the fingernails, are absent or underdeveloped, discolored, split, ridged, or pitted. The thumbnails are usually most severely affected. There are also abnormalities of the knees, elbows, and hips.
Nail disorders can often be diagnosed based on their signs and symptoms since nail disorders frequently have a characteristic appearance.
For example, an ingrown nail appears as skin growing over the edge of a nail, and the nail appears to grow underneath the skin, which is red, firm, swollen, or tender, possibly with a small amount of pus.
Diagnosis of fungal infection can be confirmed by examining scrapings from the nail under a microscope, revealing the type of fungus. Pus or fluid drained from the sore can be sent to a lab for culture to determine the type of fungus or bacteria, although results can take several weeks.
Most nail disorders do not require imaging or other diagnostic procedures.
Treatment of nail disorders varies from self-care or topical or oral medications to partial or total nail removal. People with diabetes, nerve damage, peripheral vascular disease, or other circulatory disorders should see a physician for any nail disorder. Infected nails must also be treated by a physician.
Ingrown nails infected
ingrown nails can be treated by the following:
- soaking in warm water 3–4 times per day and otherwise keeping the toe or finger dry
- gently massaging the inflamed skin
- placing dental floss or a small piece of cotton wetted with water or antiseptic under the nail
- soaking the nail in warm water to soften it before trimming
- trimming the nail straight across, without tapering or rounding the corners or trimming too short and without trying to cut out the ingrown portion
- wearing sandals if possible
- applying over-the-counter (OTC) medication for pain
A podiatrist or dermatologist can remove the ingrown portion of a nail. If the nail does not heal or ingrowth recurs, the doctor can numb the area and cut along the rim of the nail to remove it—a partial nail avulsion.
The nail will grow back in 2–4 months. For chronic ingrown nails, the corner that grows in can be destroyed or removed with cutting, a chemical, electrical current, laser, or another method so that the new nail will not grow back. Topical or oral medications are prescribed for an infection.
Treatment of fungal nails depends on the type and severity of the infection. Onychomycosis can be hard to treat; however, the longer the delay, the more complex treatment is.
Daily cleansing for many months may suppress mild infections; white marks on the nail’s surface can be filed over, and an OTC antifungal cream or ointment is applied.
Fingernail infections should be kept dry after the treatment, and a skin-drying substance such as Castellani Paint (a phenol) should be applied. However, self-treated conditions often return.
Newer oral antifungals, such as terbinafine (Lamisil) used for about three months are more effective than older treatments, and fingernail fungus can be treated for a shorter time. Lab tests must be performed to check for liver damage while taking such oral medications.
Although it can be difficult for topical treatments to reach the fungus, oral medications are not appropriate for all patients. In 2014, (FDA) the U.S. Food and Drug Administration approved two new topical solutions—efinaconazole (Jublia) and tavaborole (Kerydin)—for toenail onychomycosis.
Tavaborole is used for infections with Trichophyton mentagrophytes and Trichophyton rubrum and must be applied daily for 48 weeks.
These medications and Trichophyton mentagrophytes and Trichophyton rubrum can often be effective for mild-to-moderate toenail onychomycosis caused by skin fungi (dermatophytes) or mixed dermatophyte/Candida infection.
Some cases require laser treatments to destroy the fungus. Temporary removal of the infected nail enables the direct application of a topical antifungal. Chronically painful nails that have not responded to other treatments may be surgically removed.
Chlorine bleach (diluted 1:4 in water) applied topically can suppress the growth of P. aeruginosa. Vinegar may also be effective for bacterial paronychia. Soaking the nail in hot water 2–3 times daily helps reduce pain and swelling.
Bacterial paronychia also may be treated with oral antibiotics such as ciprofloxacin. The infection may be cut and drained for severe cases, and part of the nail may have to be removed.
GNS is usually treated by cutting the detached portion of the nail, keeping the nail dry and protected from injury, and applying topical antibiotics, such as bacitracin or polymyxin B, 2–4 times daily for 1–4 months. In severe cases, complete nail removal and an oral antibiotic are required.
Treatment of injuries depends on the type and severity. Minor cuts or scrapes can be washed gently after removing all jewelry from the hand, and a bandage can be applied if necessary.
Self-care may suffice if bleeding can be readily stopped, the nail is not cut or torn and remains attached to the nail bed, a bruise covers less than one-quarter of the nail, and the finger or toe is not bent or distorted.
More serious nail injuries require treatment in an emergency department or urgent-care center:
- The bleeding is stopped, and the wound is cleaned and numbed.
- A small hole is made in the nail for more extensive bruises to drain fluid and relieve pressure and pain.
- A vast bruise or broken bone may require nail removal and nail-bed repair.
- Nail lacerations or avulsions require removing part or all of the nail, closing cuts in the nail bed with stitches, reattaching the nail with special glue or stitches, or replacing the nail with a particular material that remains in place until the nail bed heals.
- Antibiotics are used to prevent infection.
- Pain is controlled by applying ice for 20 minutes every two hours on the first day and 3–4 times daily after that, keeping the injured hand or foot above the heart level, and taking OTC or prescription pain relievers.
Treatment of ingrown nails usually controls any infection and relieves pain, but ingrown toenails will probably recur without proper foot care. Ingrown nails can be severe in patients with diabetes, poor circulation, or peripheral neuropathies (nerve problems). In extreme cases, the infection can spread through the toe and into the bone.
Onychomycosis is cured with the growth of healthy new nails, but this may take up to one year even when treatment is successful. Medications are effective for about 50% of fungal nail infections, but the condition may return.
Untreated fungal infections progress from the tip of the nail toward the cuticle, causing the nail to thicken and discolor and become brittle, possibly with inflammation and pain. In about 1 out of every 24 untreated cases, the fungus invades other body parts, such as the foot, hand, leg, or back.
Untreated fungal infections can cause breaks in the skin that are susceptible to bacterial infection. Onychomycosis is particularly dangerous for people with conditions such as diabetic neuropathy and may ultimately require amputation.
Bacterial paronychia, including GNS, usually responds effectively to treatment. Rare complications can include abscess, permanent changes to the shape of the nail, or spread of the infection to tendons, bones, or the blood.
Injured nails are often pushed off as the new nails grow in. White spots or lines from injury eventually grow out. If a nail is lost, the nail bed will heal in 7–10 days, but it will take 4–6 months for a new fingernail to grow in and about 12 months for a toenail to grow in. The new nail usually has grooves or ridges and may be somewhat distorted, and such changes may be permanent.
Proper nail care is the primary prevention for nail disorders.
- Skin and nails should always be kept clean and dry.
- Nails should be protected from detergents and chemicals with cotton-lined rubber or plastic gloves.
- Feet should be kept clean with soap and water, dried thoroughly, and inspected regularly.
- Shoes, socks, and hosiery should be changed more than once per day.
- Shoes should fit properly with enough room around the toes, be made of breathable materials, and be alternated often.
- Cotton or wool socks should be used in preference to synthetic socks.
- Excessively tight hosiery, which can promote moisture retention, ought to be avoided.
- Shower shoes should be worn in public facilities.
- Fingernails should be trimmed weekly and toenails monthly with sharp scissors and trimmers.
- Nails should be clipped straight across and rounded slightly in the center, with toenails not extending beyond the toes. Toenails should not be tapered or rounded at the corners or trimmed too short; fingernails should have slightly rounded edges.
- An emery board should be used for smoothing edges.
- Nails should be trimmed after bathing when they are softer.
- Toenails that are thick and hard to cut should be soaked in warm salt water at —1 tsp. (5 ml) of salt per 1 pt. (473 ml) of water—for 5–10 minutes, followed by urea or lactic-acid cream to soften them.
- Cutting, manicure, and pedicure instruments should be disinfected before and after use and should not be shared.
- Cuticles should not be trimmed or removed since this can cause infection. Cuticle removers can damage the skin.
- Nails and cuticles should not be bitten, picked, or torn and should be examined regularly; nail biting can damage the skin and promote and transfer infections.
- Hangnails should be clipped off carefully rather than pulled off.
- Polish must be avoided and not applied to the nails that are red, discolored, swollen, or have any other signs of infection.
- Nail-polish remover should be acetone-free, and its use should be limited.
- Moisturizing cream should be applied to nails and cuticles, especially after using nail-polish removers that contain drying chemicals.
- Nail hardeners may help strengthen nails.
- Nail salons and technicians should be state-licensed.
- Nail salon stations and footbaths should be clean, tools should be sterilized, and technicians should wash their hands between clients.
- Frequent nail salon visitors should bring their tools.
- Nail technicians should not be allowed to cut or push back cuticles.
- Artificial nails can worsen nail disorders and should not be worn continuously by people with brittle nails or prone to fungal infections.
- Lower legs should not be shaved for at least 24 hours before a pedicure to avoid the risk of infection.
- Hands must be meticulously washed and dried after touching any type of fungal infection.
- People with diabetes should have routine nail care and foot exams.
- A dermatologist or other doctor should be consulted if changes in nail color or shape, thinning or thickening, separation of the nail from the skin, bleeding, or swelling or pain around the nails.
A red blood cell deficiency can be caused by iron deficiency and result in koilonychia.
Tearing away a body part, such as a nail.
Temporary grooves or ridges in the nail plate, usually following a severe illness.
The dead or horny layer of epidermis at the bottom and sides of the nail.
A fungal parasite of the skin or nails.
Green-nail syndrome (GNS)—
Chloronychia; nail discoloration caused by infection with the bacterium Pseudomonas aeruginosa.
Deformity of the thumbnail is caused by unconscious manipulation of the nail with the adjacent finger.
Fibrous proteins provide strength to the skin, hair, and nails.
Spoon nails; thinness or concavity of the fingernails, usually due to iron-deficiency anemia.
White spotting, streaking, or discoloration of the fingernails caused by injury or poor health.
The whitish, crescent-shaped, or half-moon mark at the base of a nail.
A rapidly spreading and deadly form of tumor that usually originates in the skin.
The skin under the nail.
A rare genetic disorder that causes absent, underdeveloped, or abnormal nails.
Thickening of a nail.
She was loosening a nail out of the nail bed, starting at the tip and extending toward the root.
Fungal infection of a nail.
Splitting or flaking of nail layers.
Describes a medication that can be obtained without a prescription.
Inflammation and infection of the tissues adjacent to a nail.
An autoimmune skin illness is marked by the buildup of dry, dead skin cells that form thick scales.
Thin, vertical lines of blood under a nail.
Bleeding under a nail.
Yellow-nail syndrome (YNS)—
A rare nail disorder associated with underlying disease.