Fingernail Cosmetics

Nail cosmetics represent a form of self-adornment allowing personal expression dictated by current fashion trends. Their popularity is greatest among females; however, the market for male manicures is rapidly growing. Forms of adornment for the fingernails and the toenails include nail polish, artificial nails, nail elongators, and nail treatment products. The goal of this article is to discuss the basic formulation and the use of these cosmetics in a medical framework.

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About Nails

In both males and females, professional grooming of the fingernails and the toenails is known as a manicure and a pedicure, respectively. The grooming includes cutting the nails according to current fashion standards, while improving their cosmetic appearance. The procedure for a manicure (grooming of the fingernails) and a pedicure (grooming of the toenails) is essentially the same. The nails are first soaked in a soapy solution to remove any debris and to soften the nail plate prior to cutting. Softening the nail is important to prevent cracking, splitting, and horizontal layering (onychoschizia), which may occur when trying to cut a brittle nail plate.

Nail Polish  -   Nail Hardener  -   Nail Enamel  -   Cuticle Remover  -   Nail Moisturizer  -   Nail Elongators  -   Nail Treatments

Current fashion dictates that the nails should be trimmed to a delicate arc at the middle of the fingertip and filed to remove any corners at the medial and lateral parts of the nail. Although this shape is esthetically pleasing and serves to create the illusion of long, slender fingers, it predisposes to nail plate fracture, hang nails, and ingrown nails. Ideally, the nail should be trimmed with as slight a curve as possible and the corners of the nail left untouched. This technique is particularly important when trimming the toenails because they frequently ingrow because of pressure from ill-fitting shoes or from trauma encountered during exercise. Recurrent ingrown toenails are best prevented by leaving the nail corners longer than the center of the toenail to create a concave shape.

Ideally, the nail plate should not be cut, but it should be frequently filed to prevent cracking through shearing forces generated by scissors or clippers. However, if cutting is necessary, the nails should be trimmed with sharp scissors or a nail clipper after softening. The cutting implement should be held perfectly perpendicular to the nail surface to avoid layering the nail plate, which predisposes to onychoschizia. Any remaining sharp edges should be filed with a diamond dust file.

Under no circumstances should the cuticle be removed or traumatized because this action may precipitate the formation of paronychia, onychomycosis, or onychodystrophy. Unfortunately, the cuticle is considered to be unattractive by most manicure artists because it complicates the even application of nail polish. Most of the problems that arise from a professional manicure are related to manipulation of the cuticle.

The last step in the manicure is grooming of the surface of the nail plate. Sometimes, this step is as simple as buffing the nail plate to a shine with creams containing finely ground pumice, talc, kaolin, or precipitated chalk as abrasives, with wax added to increase nail shine. A white pencil, also known as nail white, is sometimes stroked beneath the free edge of the nail plate to brighten the nail. Females may prefer to use nail polish or other nail decoration.


Prior to 1920, nails were manicured and then rubbed with abrasive powder to achieve a shine. Color was added through the use of stains. In 1930, Charles Revson developed the first pigmented, opaque nail polish, which launched Revlon, still a major manufacturer of nail cosmetics today.

Nail polish basically consists of pigments suspended in a volatile solvent to which film formers have been added. The ingredients are as follows:

  • Primary film former (nitrocellulose, methacrylate polymers, vinyl polymers)

  • Secondary film-forming resin (formaldehyde, p- toluene sulfonamide, polyamide, acrylate, alkyd, vinyl resins)

  • Plasticizers (dibutyl phthalate, dioctyl phthalate, tricresyl phosphate, camphor)

  • Solvents and diluents (acetates, ketones, toluene, xylene, alcohols)

  • Colorants (organic D&C pigments, inorganic pigments)

  • Specialty fillers (guanine, fish scale, titanium dioxideЦcoated mica flakes, or bismuth oxychloride for iridescence)

  • Suspending agents

Nitrocellulose is the most commonly used primary film-forming agent in nail lacquer. It produces a shiny, tough, nontoxic film that adheres well to the nail plate. The film is somewhat oxygen permeable, allowing gas exchange between the atmosphere and the nail plate; this gas exchange is important for ensuring nail plate health. Resins and plasticizers are then added to increase the flexibility of the film, minimizing chipping and peeling.

The most popular resin used to enhance the nitrocellulose film is toluene-sulfonamide-formaldehyde; however, it is the source of allergic contact dermatitis in some nail enamels. Hypoallergenic nail enamels use polyester resin or cellulose acetate butyrate, but sensitivity is still possible. Plasticizers, such as dibutyl phthalate, are also used to keep the product soft and pliable. All of these ingredients are dissolved in a solvent, such as N- butyl acetate or ethyl acetate, with toluene and isopropyl alcohol added as diluents.

Variety in nail polish color can be achieved through the addition of coloring agents, such as organic colors, selected from a Food and Drug Administration (FDA)Цapproved list of certified colors. Inorganic colors and pigments may also be used, but they must conform to low heavy metal content standards. These colors can be suspended within the lacquer with suspending agents, such as stearalkonium hectorite, to produce a range of colors, including white, pink, purple, brown, orange, blue, or green. If the pigments are dissolved rather than suspended in the polish, nail staining is more likely.

Other specialty additives can also create variety. Guanine, fish scale, bismuth oxychloride, or titanium dioxideЦcoated mica flakes can be added to enhance light reflection and to give a frosted appearance. Chopped aluminum, silver, and gold can be added for a metallic shine. Nylon or rayon fibers can be added for nail-strengthening purposes. Other agents can also be added for nail treatment purposes, a topic discussed in detail later.


After a manicure, the patient may elect to have nail enamel applied. A professional nail enamel application requires 3 layers of polish: a base coat, a pigmented nail enamel, and a topcoat. The base coat ensures good adhesion to the nail plate and prevents the polish from chipping. It contains no pigment, less primary film former, and more secondary film-forming resins, and it is of a lower viscosity because a thinner film is desirable. The second layer is the actual pigmented nail enamel. The topcoat, or third layer, provides gloss and resistance to chipping. It contains increased amounts of primary film former, more plasticizer, and less secondary film-forming resins. Some topcoats may contain a chemical sunscreen, which is designed to prevent the nail polish color from fading, not to protect the nail bed from ultraviolet light damage.

Dermatologic considerations

Dermatologic problems associated with nail enamels include nail plate discoloration and allergic contact dermatitis. The nail staining, as mentioned previously, is seen with dissolved rather than suspended pigments, and it is most common in deep red nail polishes that contain D&C Reds No. 6, 7, 34, or 5 Lake . The nail plate is stained yellow after 7 days of continuous wear. The staining fades without treatment approximately 14 days after the enamel has been removed. Scraping of the nail plate with a scalpel blade can be used to confirm that only the nail surface has been stained; this finding is an important distinction in nail pigmentation abnormalities.

Allergic contact dermatitis to nail polish may present as proximal nail fold erythema and edema, fingertip tenderness and swelling, and/or eyelid dermatitis. The North American Contact Dermatitis Group determined that 4% of positive patch test results were due to toluene-sulfonamide-formaldehyde resin. Even though the allergic reaction is most commonly due to wet nail enamel, Tosti et al found that 11 of 59 patients who had positive patch test results to wet polish also reacted to the dried enamel. Allergic reactions can be severe, necessitating lost work time or, rarely, hospitalization.

Some concern exists that the use of nail polish can contribute to nail dryness and brittleness. This actually is not the case. Nail polish prevents contact of detergents with the nail, acting as a protectant. Furthermore, it decreases nail water vapor loss from 1.6 mg/cm 2 /h to 0.4 mg/cm 2 /h; this decrease enhances nail moisturization and flexibility. The dryness associated with nail polish is actually due to the nail polish remover, which is usually a harsh acetone-based solvent.

Nail polish can be tested Уas is,Ф but it should be allowed to thoroughly dry because the volatile solvent can cause an irritant reaction if not allowed to rapidly evaporate. The toluene-sulfonamide-formaldehyde resin can also be tested alone in 10% petrolatum. Patients who are allergic to this resin may experience no difficulty with hypoallergenic nail polishes, but allergic contact dermatitis is still a possibility. Nail enamels may contain metallic beads to aid in the dispersion of the products before application. These beads contain nickel; therefore, nickel sensitivity can occur with nail enamel usage.

Nail HardenerFormulation

Nail hardeners are used to increase the strength of brittle nails caused by nail plate dehydration due to excessive contact with solvents, detergents, and water. Originally, nail hardeners were formulated as 10% or greater solutions of formaldehyde; however, the FDA recalled these products following reports of onycholysis, subungual hyperkeratosis, reversible subungual hemorrhage, bluish discoloration of the nail plate, and allergic contact dermatitis in the dermatologic literature.

Free formaldehyde in concentrations of 1-2% is still permitted, but acetates, toluene, nitrocellulose, acrylic, and polyamide resins are now used to structurally reinforce the nail plate. Some products actually contain 1% nylon fibers and are known as fibered nail hardeners. Other additives purported to strengthen the nail include hydrolyzed proteins, modified vegetable extracts, glycerin, propylene glycol, and metal salts.


Nail hardeners are essentially a modification of clear nail enamel with different solvent and resin concentrations. They are the first coat of enamel applied to the clean nail plate and function as a base coat.

Dermatologic considerations

Nail hardeners may contain the same toluene-sulfonamide-formaldehyde resin as nail polish, and the same dermatologic considerations apply.

nail enamelFormulation

Nail polish removers are liquids designed to strip the nail polish from the nail plate. They may contain strong solvents, such as acetone, alcohol, ethyl acetate, or butyl acetate. Conditioning nail enamel removers are available containing fatty materials, such as cetyl alcohol, cetyl palmitate, lanolin, castor oil, or other synthetic oils. These oily substances are thought to act as occlusive nail moisturizers retarding water evaporation; however, their effectiveness is minimal compared with the dehydrating effect of the strong solvents required to dissolve the nail enamel.


Nail enamel remover is applied to a tissue or a cotton ball and wiped across the nail plate to remove old or unwanted nail polish. Several applications and rubbing may be required to remove the polish if several coats have been applied.

Dermatologic considerations

Nail polish remover can irritate and dry the nail plate and surrounding skin. It can also contribute to nail dryness and brittleness. These problems can be minimized by using the product once a week or less.

Only open patch testing should be attempted with nail polish remover because of its high solvent concentration. It may be tested at a concentration of 10% dissolved in olive oil.

Cuticle RemoverFormulation

The cuticle can be removed mechanically by pushing and trimming or chemically through the use of cuticle removers, which are formulated as liquids or creams that contain an alkali to destroy cuticle keratin. The active agent is usually 2-5% sodium hydroxide or potassium hydroxide with propylene glycol or glycerin added as a humectant. Milder preparations can be made with trisodium phosphate or tetrasodium pyrophosphate, but they are also less effective.

A subset of products within this category is known as cuticle softeners. These products are quaternary ammonium compounds in a 3-5% concentration, and they are sometimes combined with urea. They are designed to soften the cuticular protein and to facilitate mechanical removal.


Cuticle removers dissolve excess cuticular tissue on the nail plate. They are not intended to remove the fibrous cuticular ridge; however, vigorous use can remove the entire cuticle. The product is applied with a cotton ball, and it is left on the nail plate for 10 minutes followed by removal with wiping.

Dermatologic considerations

Removal or manipulation of the cuticle is not recommended; paronychial inflammation with secondary bacterial infection or yeast colonization can occur. Cuticle removers can also damage the nail plate through softening. Because of the high alkali content of these products, irritant contact dermatitis is common if the product is left on too long. Thus, these products should not be used in closed patch testing. Open patch testing in a 2% aqueous concentration may be used, if necessary.

Nail MoisturizerFormulation

Nail moisturizers are valuable in patients with dry, brittle, fissured, and/or splitting nails. The healthy nail contains about 16% water, becoming soft with saturation at 30%. The water content of nail keratin is proportional to the relative humidity, being 7% at 20% relative humidity and 30% at 100% relative humidity. The idea of applying a cream or a lotion to the nails to increase the nail water content is somewhat new.

Nail moisturizers are usually creams or lotions that contain occlusives, such as petrolatum, mineral oil, or lanolin. Humectants, such as glycerin, propylene glycol, and proteins, may also be added. Alpha-hydroxy acids, lactic acid, and urea are active ingredients used to increase the water-binding capacity of the nail plate. A well-formulated nail moisturizer should contain substances from all of the aforementioned groups to maximally treat the dehydrated nail plate.

Recent studies demonstrated that daily oral biotin supplementation may be helpful in treating brittle nails; however, no evidence exists that topical biotin added to nail moisturizers has a similar beneficial effect. Furthermore, no evidence exists that topical gelatin, calcium, iron, botanical extracts, and biological extracts are effective in treating nail dehydration.


Nail moisturizers function best if the nails are first soaked for 10-20 minutes in lukewarm water, preferably at bedtime. The moisturizer should then be generously applied under occlusion with a light cotton glove or sock. This procedure should be repeated nightly for at least 3 months. Certainly, activities contributing to dry nails, such as frequent contact with water, detergents, solvents, or nail polish remover, should be discontinued.

Dermatologic considerations

Alpha-hydroxy acids, lactic acid, and urea can cause stinging and irritant contact dermatitis in susceptible individuals. Wounds on the hands or fissured cuticles can burn if high concentrations of these substances are used. Most over-the-counter preparations contain 5% or less of these active agents; however, prescription preparations of lactic acid are available in strengths of 12% and 30%.

Nail ElongatorsNail elongators are cosmetic methods of creating the illusion of nail length. This technique can be accomplished through the use of preformed plastics, formed acrylics, or a combination of both methods.

Preformed artificial nails

Preformed plastic nails are popular home nail elongators available in press-on and preglued forms and in forms that require the application of glue. The acrylic glue used for adhesion is typically methacrylate based and a possible cause of allergic contact dermatitis. A stronger nail adhesive made from ethyl 2-cyanoacrylate provides better adhesion, but it can cause onycholysis. Traumatic removal of artificial nails may result in onychoschizia and nail pitting.

Sculptured nails

An increasingly popular method of obtaining long, hard nails is the application of sculptured nails. The word sculptured is used because the custom-made artificial nail is sculpted on a template attached to the natural nail plate. The sculpted nail fits perfectly and, if applied well, can be hard to differentiate from a natural nail.

The application of sculptured nails is an involved process requiring approximately 2 hours to sculpt 10 fingernails. The basic process is as follows:

  • All nail polish and oils are removed from the nail.

  • The nail is roughened with a coarse emery board, pumice stone, or grinding drill to create an optimal surface for adhesion of the sculpted nail.

  • An antifungal, antibacterial liquid, such as decolorized iodine, is applied to the entire nail plate to minimize onychomycosis and paronychia.

  • The loose edges of the cuticle are trimmed, removed, or pushed back, depending on the operator.

  • A flexible template is fit beneath the natural nail plate, upon which the elongated sculpted nail is built.

  • The acrylic is mixed and applied with a paintbrush to cover the entire natural nail plate, and it is extended onto the template to the desired nail length. A clear acrylic is used over the natural nail plate attached to the nail bed through which the natural pink color can be seen. A white acrylic is used from the free edge of the nail plate distally. This combination perfectly simulates a natural nail, so enamel need not be worn. It also allows both men and women to use sculptured nails.

  • The final nail sculpture is sanded to a high shine.

  • Nail polish, jewels, decals, and decorative metal strips may be added, depending on the fashion tastes of the individual.

Originally, methyl methacrylate was the monomer used to fashion the nail, but it has been removed from the market because of its sensitizing potential. Currently, liquid ethyl or isobutyl methacrylate is used as the monomer, and it is mixed with powdered polymethyl methacrylate polymer. The product is allowed to polymerize in the presence of a benzoyl peroxide accelerator, and a formable acrylic, which hardens in 7-9 minutes, is made. Usually, hydroquinone, monomethyl ether of hydroquinone, or pyrogallol is added to slow down polymerization.

Many individuals are not aware that the finished nail sculptures require more care than natural fingernails. With continued wear of the sculptured nail, the acrylic loosens from the natural nail, especially around the edges. These loose edges must be clipped, and new acrylic must be applied approximately every 3 weeks to prevent development of an environment for infection. The sculptured nail grows out with the natural nail plate, and more polymer must be added proximally, depending on the growth rate of the nail. This procedure is known as filling. If necessary, the sculptured nails can be removed by soaking them in acetone.

Allergic contact dermatitis remains an issue even though methyl methacrylate is no longer used; isobutyl, ethyl, and tetrahydrofurfuryl methacrylate are still strong sensitizers. However, the polymerized, cured acrylic is not sensitizing, only the liquid monomer. Therefore, a careful operator who avoids skin contact with the uncured acrylic can avoid sensitizing the patient. Patch testing should be performed with methyl methacrylate monomer, 10% in olive oil, and methacrylate acid esters, 1% and 5% in olive oil and petrolatum, in individuals with suspected sensitization.

Sculptured nails with tips

Another technique of elongating nails is to combine custom-made sculptured nails with preformed artificial tips, which involves gluing a preformed plastic piece to the tip of the nail and then applying a smaller amount of the liquid acrylic to the remaining exposed natural nail. The natural nail can be visualized beneath the artificial nail. This technique is the most popular form of nail elongation used today because operator time is greatly reduced because most of the nail is preformed.

Photobonded nails

A variation on sculptured nails is known as photobonded nails. These nails are also formed from a cured acrylic sculpted on the natural nail, but, instead of allowing the acrylic to cure (dry) at room temperature, the nails are placed under a magnesium light for 1-2 minutes. This technique is similar to restorative dental bonding. Photo-onycholysis and paresthesias have been reported as a result of this technique, which is currently the least popular of all the nail elongation methods.

Nail TreatmentsNail treatment products are actually a subgroup of nail polishes with added ingredients intended to produce some therapeutic benefit. Therapeutic benefits include decreased nail breakage, increased nail growth, and prevention of fungal infections. Products designed to strengthen nails may contain substances, such as iron or calcium, but these products are essentially nail enamels that are applied before the pigmented nail polish (base coat) or after the pigmented nail polish (top coat). Each successive coat of polish thickens the nail plate and, to some extent, makes the nail less subject to breakage. Nail growth polishes may actually contain some fibered material, such as silk proteins, to add further nail support.

Perhaps the most interesting nail treatment products to the dermatologist are those liquids designed for nail fungal infections. The active ingredient in most of these over-the-counter formulations is 1% tolnaftate in liquid form that is applied beneath the nail plate.