Adverse Effects of Do-It-Yourself Nail Cosmetics: A Literature Review

Abstract Background: As self-applied manicures have gained popularity, it is important for physicians to remain informed about potential associated side effects. Traditional polish remains most popular among nail enthusiasts, but the pursuit of durability and convenience accelerated development of other nail cosmetic products, including gel polish, acrylic nails, and press-on nails. Despite documented adverse effects among beauty professionals and salon customers, individuals practicing at-home nail care routines may face similar, if not more, frequent complications due to misinformation, inadequate training, and social media trends. Summary: This review provides an overview of adverse effects associated with different at-home nail cosmetics. Allergic contact dermatitis is the most prevalent adverse event, primarily attributed to (meth)acrylates found in nail glue, gel polish, and acrylic nails. Other adverse effects include infections, chemical burns, and complications from ultraviolet nail lamps. Key Message: The review highlights the importance of transparent product labeling and appropriate warning labels from manufacturers, as well as physician education and awareness for minimizing risks related to at-home nail cosmetic applications.


Introduction
When nail salons shut down following the COVID-19 pandemic, many people started experimenting with at-home manicures.While traditional nail polish remains a popular choice, the desire for longer lasting nails and easy application process has led to the development of innovative nail cosmetic products.Over the years, gel nail polish and acrylic nails gained widespread popularity due to its durability and longevity compared to regular nail polishes.Additionally, press-on nails are extremely convenient with their simple glue-on application process.These easily accessible and cost-effective alternatives allow individuals to keep up with ever-changing nail art trends.Numerous video tutorials, created by experienced nail artists and nail enthusiasts, are readily accessible for those interested in do-it-yourself nail cosmetics applications.However, many consumers are not aware of the consequences of improper application of nail products.In addition, not all trending nail tutorials on these platforms adhere to accurate and safe techniques.
Recently, there have been numerous reports concerning complications and adverse outcomes related to at-home nail products.Our objectives were to review adverse events associated with nail cosmetics applied athome to provide recommendations for dermatologists and podiatrists counseling their patients.

Methods
A literature search was conducted using PubMed and supplemented with Scopus and Web of Science using the following terms: nails, nail diseases/chemically induced, cosmetics/adverse effects, nail cosmetics, nail polish, nail varnish, nail lacquer, gel nail, acrylic nail, artificial nail, acrylate, manicure, and pedicure.Only English language articles were included.Full-length articles and abstracts were screened to assess their relevance and whether the nail cosmetics were self-applied.A total of 493 articles were identified, and 49 relevant articles were selected for review after applying inclusion and exclusion criteria.

Nail Cosmetics and Associated Adverse Events
There are many different types of at home nail products currently available and marketed as being easy to apply, convenient, and long-lasting.Each type of nail cosmetic is discussed below along with associated adverse events.

Press-On Nails/Preformed Nails
Press-on nail sets are artificial nails that may be applied at home.These press-on nail kits include plastic tips in various shapes and colors, tailored to fit each fingernail.While most kits are designed for one-time use with included nail glue, others provide a peel-and-stick adhesive or are marketed as reusable with reapplication of glue.The nail tips are applied on clean nails, typically lasting for 1 to 2 weeks.The accompanying nail glues often contain common allergens, typically composed of methacrylate or cyanoacrylate (Table 1).In several case reports, allergic contact dermatitis (ACD) to methacrylate in nail glue was diagnosed via patch testing [1,2].Several other case reports of ACD to nail glues containing ethyl cyanoacrylate reported dermatitis at remote sites such as dorsal hands, face, eyelids, and trunk [3,4]; fingertip eczema [4]; onychodystrophy [4,5]; onycholysis [5,6]; and leukonychia [7].
Extended use of press-on nails is associated with increased risk of bacterial infections and colonization, such as greennail syndrome [8].Green-nail syndrome is characterized by the blue-green pigment pyoverdine and pyocyanin, synthesized due to Pseudomonas aeruginosa colonization.
Additionally, press-on nail glue spills can cause chemical burns through an exothermic reaction with cotton, a catalyst that expedites the polymerization of the glue.Despite numerous reported injuries, product warning packaging often lacks information about burn risks and protocols for treating injuries.Accidents often occur due to the lack of supervision in the pediatric population.In 8 publications with 14 cases of nail glue burns, most caused full thickness burns to the leg or foot from spillage, exacerbated by the lack of information on first aid.Many patients required skin grafts, some patients had infections, and healing time ranged from 2 weeks to 5 months [9][10][11][12][13][14][15].

Gel Nail Polish
Gel nail polish premixes are acrylic-based or cyanoacrylate-based monomers and oligomer requiring at least 3 coats of polish applied onto natural or nail extensions: base coat, layer of colored polish, and topcoat.To dry and harden the layers, light sources are used with curing time of approximately 2 min with ultraviolet (UV) lamps, emitting UVA light, and 30 s with light-emitting diode lamps.To remove gel nail polish, the nail plate is soaked with 100% acetone wrapped in aluminum for 10-15 min or a nail drill can be used to fill away the polish.
Cases of ACD secondary to gel polish have been reported in manicurists and salon clients [16,17], with increased incidence in individuals who use nail kits at home.In Sweden, a particular at-home gel polish brand triggered sensitization in 65 users, causing nail fold dermatitis, finger pruritus and discomfort, onycholysis, paronychia, brittle nails, and dermatitis in distal body regions including the lips, neck, and periocular areas [18].Cheilitis and lip edema were also reported [19].
Nail involvement may sometimes be the only manifestation of acrylate ACD, which was reported in 4 cases [20,21].All patients presented with psoriatic-like nail findings without typical eczematous changes.In 1 patient, ACD to methacrylate was confirmed with patch testing.Splinter hemorrhages alone, without cutaneous lesions, have also been reported [22].
Accidental and unsupervised use of at-home nail products was associated with two pediatric cases with dermatitis secondary to meth(acrylates) in gel polishes.Both cases presented with eczematous changes on the digits and hands [23,24].Other variants of gel nail polish, including "hybrid" gel polishes that are cured with natural daylight, may induce ACD [25].
UV lamps carry some potential risks of photosensitivity.One case report identified UV nail lamp usage as a potential trigger for development of solar urticaria in a patient without a known history of photosensitivity or a drug-related cause [26].Two patients with a history of both systemic lupus erythematosus and discoid lupus erythematosus developed cutaneous lupus erythematosus following gel manicures cured with UV nail lamps [27].
There are also concerns about UV nail lamps in relation to carcinogenesis risk.Initial concerns were raised with a report of a squamous cell carcinoma (SCC) in situ on the dorsomedial aspect of the right index finger in a 55-yearold female with a 15-year history of UV nail lamp usage and development of four SCCs on dorsal hands in a 48year-old female, following frequent use of UV lamps [28].Subsequently, actinic damage and/or SCC involving irradiated areas of hands and feet has been reported [29][30][31].
While the in vivo risk from multiple manicure visits remains untested, there are conflicting views on the safety of UV nail lamps, which predominantly utilize UVA bulbs.An observational study sampled various UV lamps at nail salons and discovered a nonhomogeneous distribution of irradiance under each lamp, along with broad variations in total irradiance among different commercial nail lamps.Certain lamps reached the median energy density threshold to cause DNA damage of 600 kJ/m 2 after 8 usages, while others achieved this threshold after 208 usages [32].One mathematical model calculated carcinogenic equivalence of the irradiances of the UVA lamps and determined it would require at least 13,700 nail lamp sessions to achieve the same narrowband UVB exposure [33].Another algorithm determined that certain lamps would require 30-49 min of daily exposure to exceed the weighted irradiance of photobiological safety [34].Despite differing views, an area of consensus lies in acknowledging the potential harm from the accidental installation of the wrong light bulbs.Instead of UVA, the potent carcinogenic radiation emitted by UVB bulbs can theoretically increase the risk of injury [35].Given potential risks of development of skin cancers with UV lamps, physicians may recommend caution and advise protective measures, such as using gloves or sunscreen, especially with frequent use.Shellac nail polish is a combination of two different types of polishes, with gel polish providing durability and traditional nail polish for the color.Similar to traditional gel nail polishes, shellac nails are polish-gel hybrid formulation that also require UV lamps for curing and may be performed in a salon or at home.A case series describes 4 patients who experienced acrylate-related ACD to shellac gel nails.Dermatitis involving the surrounding skin was reported [36].

Acrylic Nails
While acrylic nails are typically applied at a nail salon due to the skill involved, they may also be applied at home.They are formed by mixing a liquid monomer with a polymer powder to create a mixture that is applied and sculpted onto the nail.The acrylic nails harden through air-drying and do not require UV or light-emitting diode lamps.
Acrylic nails are extremely durable and strong.For certain professionals, including flamenco guitarists, having strong nails is essential.Presentation includes onychodystrophy, onycholysis, and paronychia [37].
Much like gel polish, acrylic nails require acetone soaking or use of a mechanical nail drill for removal.Using a nail drill, without proper training or when overly aggressive may damage the nail bed or matrix.A similar outcome may occur in individuals who file their nails with a nail buffer."Worndown nail syndrome" characterized by the thinning of the distal nail plate due to over-filing nails may develop [38].

Nail Hardeners
Nail hardeners are used to promote nail strength and protection.They may also be used as a deterrent for nail biting habits, in both adults and children [39].Similar to certain gel polishes, nail hardeners often contain tosylamide/formaldehyde resin, with reported cases of ACD as early as 1988 [40].Presentations of ACD secondary to tosylamide/formaldehyde resin in nail hardeners include erythema, edema, and scaling of the face and neck [39].Angioedema involving the eyelids and lips with tongue swelling [41] as well as onycholysis has been reported [42].

Nail Varnish
The history of modern nail polish began in 1916 by the company Cutex, with the development of basic nail polish components, including color pigments, film-forming agents like nitrocellulose, resins including tosylamide formaldehyde resin for adhesion, plasticizers for flexibility, and solvents for drying.ACD from regular nail polish is uncommon and may be secondary to toluene/ formaldehyde resin, formaldehyde, polyester resin, pigments, or nitrocellulose [43].More recently, manufacturers have started to produce nail polishes that exclude some of these common allergens.
One of the most common allergens in nail varnishes is tosylamide/formaldehyde resin.Multiple cases reports, in both adults and children, described ACD involving the head, neck, nose, ears, and eyelids [44][45][46].
ACD to phthalic and trimellitic anhydride/glycols copolymer in nail varnish commonly presents with dermatitis involving the head and neck.Case reports have described dermatitis involving the face, neck, and periorbital areas, accompanied by episodes of eyelid swelling due to phthalic and trimellitic anhydride/glycols copolymer [47], with some cases lasting several months [48][49][50].

Nail Art Additions
With the abundance of different products available for nail adornment, some individuals mix and match different products during application.Engaging in recreational nail art as a hobby, individuals may seek out products that offer various finishes, such as glitter, which can also trigger sensitivity.Eczematous periungual and palmar lesions may develop, with negative patch testing to acrylates in gel polish and positive patch testing to cobalt chloride polish [51].Brands and nail art enthusiasts lacking professional training may overlook the importance of identifying product chemical composition.

Discussion
As the availability of at-home nail products increased, an understanding of associated skin and nail complications is important.ACD presents with a wide range of manifestations, from nail-specific issues to those mimicking systemic diseases.Reactions may occur at the application site or at distant locations.Clinical presentations include onychodystrophy, subungual hyperkeratosis, onycholysis, splinter hemorrhages, dermatitis in the nail folds and digits, vesicular lesions on fingertips, paresthesia or burning of fingertips, and erythematous plaques on the face and neck.Patch testing is necessary to confirm ACD and guide patients on specific allergens to avoid.
Misinformation and inadequate training might contribute to the growing prevalence of allergen sensitization.Many products lack detailed information on application processes and warnings about improper usage.For instance, applying overly thick gel coats or allowing insufficient curing time may contribute to development of ACD due to incomplete polymerization and the presence of uncured monomers.Social media trends, including curing gel polish under nontransparent press-on nails, may similarly cause the gel polish to remain in their semiliquid state causing sensitization to monomers.Mismatching different nail products and their associated lamps, incorporating various glitters and add-ons, and frequent product changes may also result in improper curing and potential product interactions, emphasizing the need for meticulous review of products used before deciding on compound patch testing.
Even with proper education, errors during nail applications may occur, increasing the risk of sensitization.Accidental skin application, spills, and improper nail preparation contribute to these risks.Onychodystrophies, easily masked by cosmetics, require careful inspection and removal of all polishes.

Conclusion
Nail cosmetics, while not inherently harmful, may be associated with significant adverse events.Manufacturers are now striving to develop allergen-free products to cater to consumers who may have sensitivities.Transparent ingredient labeling and appropriate warning labels are crucial aspects for manufacturers to uphold.Beyond their decorative function, nail cosmetics also serve practical purposes such as repairing damaged nails and acting as a deterrent for nail-biting habits.Given the diverse presentations of dermatological manifestations associated with nail cosmetics, it is important for physicians to recognize adverse events associated with nail cosmetics to enhance diagnostic accuracy and facilitate timely treatment intervention.

Table 1 .
Summary table