4.4 Skin Disorders, Lesions & Adverse Reactions to Nail Services

Key Takeaways

  • A primary skin lesion appears at the start of a condition (for example a macule, papule, vesicle, or pustule); a secondary lesion develops later (for example a crust, scale, fissure, or ulcer).
  • Allergic contact dermatitis from acrylates is a delayed immune reaction that can appear hours to days after exposure and can become permanent sensitization.
  • Irritant contact dermatitis is direct skin damage from products such as solvents, soaps, or alkaline cuticle removers, and it does not require prior sensitization.
  • A changing mole that is asymmetrical, has irregular borders, uneven color, a larger diameter, or is evolving (the ABCDE signs) should be referred to a physician, not serviced over.
  • When a client has an adverse reaction, stop the service, remove the product from the skin, avoid reapplying it, document the event, and refer the client to a physician.
Last updated: September 2026

Your service area covers the hands, forearms, feet, and lower legs — a lot of skin. Clients often show nail technicians rashes, spots, and irritation before they show a doctor. The NIC theory outline asks you to "recognize signs, symptoms, and cause of disorders, diseases, and conditions" of the skin and to "identify adverse reactions to products or services." Your job is not to diagnose. It is to recognize, protect, adjust, and refer.

Skin Lesions: The Vocabulary of Skin Changes

A lesion is any mark or structural change in the skin. Primary lesions appear at the start of a condition. Secondary lesions develop as it progresses, or from scratching, healing, or injury.

Primary lesionDescriptionNail-service example
MaculeFlat spot of color change, not raisedFreckle; flat brown age spot on the back of the hand
PapuleSmall, solid, raised bump without fluidInsect bite; early wart
VesicleSmall blister filled with clear fluid (under 1 cm)Allergic reaction around the nail folds; herpes lesions
BullaLarger blister over 1 cmFriction blister on a heel
PustuleRaised lesion containing pusInfected hangnail
WhealItchy, swollen, short-lived raised areaHives; insect sting
Nodule / tumorSolid mass, deeper or larger than a papuleGrowth that needs medical evaluation
CystClosed sac holding fluid or semi-solid materialGanglion-like swelling near a joint
Secondary lesionDescription
ScaleFlakes of dead skin cells (dry skin, psoriasis)
CrustDried fluid, blood, or pus over a lesion (scab)
FissureCrack in the skin that may reach the dermis (cracked heels)
ExcoriationScratch or abrasion from scratching or scraping
UlcerOpen lesion with loss of deeper skin tissue (diabetic foot ulcer)
Scar / keloidHealed tissue; a keloid is a thick, overgrown scar

Service rule of thumb: open, weeping, crusted, pus-filled, or ulcerated skin is broken skin. Do not service the area, and refer when the cause is unknown.

Inflammatory Skin Conditions

  • Dermatitis: general inflammation of the skin — redness, itching, swelling, and sometimes blisters or scaling. Contact dermatitis, described below, is the type most connected to nail services.
  • Eczema: a chronic inflammatory condition with dry, itchy, red, scaly or weeping patches. It is not contagious, but broken or flaring skin should not be serviced. Choose fragrance-free products and avoid harsh scrubs on intact areas.
  • Psoriasis: a chronic, non-contagious autoimmune condition with red patches covered by silvery scales, often on elbows and knees. Do not service open or bleeding plaques. Nail psoriasis is covered in Section 4.3.
  • Urticaria (hives): itchy wheals, sometimes a reaction to a product, medication, or food. Stop the service if hives appear during it.

Infectious Skin Conditions Seen in Nail Services

ConditionCauseTypical appearanceService action
Tinea pedis (athlete's foot)FungusItchy, scaling, cracked, or soggy skin between the toes or on the solesNo pedicure; refer
Tinea manuumFungusScaly, ring-like, itchy patches on the handNo service on the area; refer
Verruca (wart), including plantar wartsHuman papillomavirusRough raised growth; plantar warts may show tiny black dotsDo not file or cut; avoid the area or refer
ImpetigoBacteriaHoney-colored crusts over blisters or soresContagious — no service; refer
CellulitisBacteriaSpreading red, hot, swollen, painful skinNo service; urge prompt medical care
Herpes simplex (including herpetic whitlow)VirusPainful grouped blistersNo service; refer (Section 4.1)

Gland, Pigment, and Growth Disorders

  • Hyperhidrosis: excessive sweating, common on the palms and soles. It can shorten polish and enhancement wear, so dehydrate thoroughly and set expectations.
  • Bromhidrosis: foul-smelling sweat, often on the feet. Anhidrosis: lack of sweating.
  • Keratoma: a thickened patch of skin, such as a callus. A corn is a keratoma with a painful central core over a bony pressure point. Both are softened and gently smoothed, never cut (Section 7.2).
  • Hyperpigmentation (darker patches), lentigines (freckle-like spots), and vitiligo (milky-white patches from pigment loss) are not contagious, and services may proceed.
  • Nevus (mole): usually harmless, but watch for changes.

Skin Cancer Warning Signs

  • Basal cell carcinoma: a pearly or shiny bump, or a sore that bleeds and does not heal.
  • Squamous cell carcinoma: a scaly red patch or a firm, crusted nodule.
  • Melanoma: the most dangerous type. Use the ABCDE guide: Asymmetry, Border irregularity, Color variation, Diameter larger than a pencil eraser (about 6 mm), and Evolving size, shape, or color. Melanoma can occur on the palms, soles, and under the nails.

If you notice a changing or bleeding spot, mention it privately and suggest a physician or dermatologist. Never cover an evolving lesion with product.

Adverse Reactions to Nail Products and Services

ReactionCommon causes in nail servicesWhat you seeImmediate response
Allergic contact dermatitisUncured acrylic monomer, uncured gel and inhibition-layer residue, some primers and adhesives, formaldehyde-type hardeners, fragrances, latexItching, redness, swelling, or tiny blisters around the nail folds and fingertips. It can appear hours to days later and sometimes on the eyelids, face, or neckRemove product from skin; stop using that product on the client; document; refer to a physician
Irritant contact dermatitisRepeated acetone or solvent soaking, harsh soaps, alkaline cuticle removers or callus softeners left too longDry, red, rough, cracked, or stinging skin where the product touchedRinse thoroughly; shorten exposure; condition the skin; postpone if skin is broken
Chemical burnAcid primer on skin; strong alkaline softenersStinging, whitening, redness, blisteringStop; flush with plenty of cool running water; follow SDS first-aid measures; refer
Heat spikeToo-thick gel or acrylic, thin or over-filed natural nails, fast-curing lampsSudden burning under the nail during curingRemove the hand from the lamp; apply thinner layers; use low-heat or flash curing
Friction burn / "rings of fire"Electric file at the wrong angle or speedPainful, red grooves in the nail plate near the cuticleStop filing; do not apply product over damaged areas; retrain technique
Onycholysis after servicesOver-filing, allergy, trauma from prying off enhancementsWhite separated area under the plateRemove enhancements gently; keep short and dry; refer if unexplained
Pedicure-bath infectionPoorly cleaned foot spas; skin nicked from recent shavingBoils or sores on the lower legs days to weeks laterRefer immediately; review basin disinfection (Section 7.2)

Irritant vs. Allergic: The Key Distinction

Irritant reactions are direct chemical damage. They can happen to anyone on first exposure, and they stay where the product touched. Allergic reactions involve the immune system. They require prior sensitization, often appear after a delay, can spread beyond the contact area, and tend to get worse with each exposure. Once someone is sensitized to acrylates, even tiny amounts may trigger a reaction. The best prevention is keeping monomers, uncured gels, and adhesives off the skin, fully curing products, and never touching the client's skin with contaminated brushes or wipes.

A Five-Step Adverse Reaction Protocol

  1. Stop the service as soon as the client reports burning, itching, or pain, or you see a reaction.
  2. Remove the product from the skin by rinsing with soap and water. For chemical splashes, follow the product's SDS first-aid section.
  3. Do not reapply the suspected product, and do not cover the reaction with polish or enhancements.
  4. Document the date, service, products and brands used, and what you observed in the client record.
  5. Refer the client to a physician for anything beyond mild, short-lived redness.

Scenario: The Itchy Fingertips

A regular gel-polish client calls two days after her appointment with itchy, puffy skin around several nail folds and tiny blisters along her fingertips. When she comes in, you see the gel is intact, but the skin is inflamed.

This pattern points to possible allergic contact dermatitis. You should not diagnose it, and you should not apply more gel. Gently remove the gel as the manufacturer directs, avoiding the irritated skin. Record the products you used, and recommend that she see a physician or dermatologist before any future acrylate-based service. Then review your technique: keep gel off the skin, wipe the inhibition layer away from the nail folds, and check that the lamp matches the gel system.

Test Your Knowledge

A client has a small, raised blister filled with clear fluid beside the nail fold. Which primary lesion term describes it?

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Test Your Knowledge

Which feature best distinguishes allergic contact dermatitis from irritant contact dermatitis after a nail service?

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Test Your Knowledge

During an acrylic service, a client says the skin at her nail fold is suddenly stinging after a drop of acid-based primer touched it. What should the technician do first?

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