Artificial nails can result in acute or chronic nail unit inflammation and damage. There are 3 major types of artificial nails: methacrylate sculptured nails, nails treated with light-activated gels, and preformed artificial nails. All 3 types of artificial nails utilize acrylates, which are strong bonding chemicals (similar to Crazy Glue). Acrylates can often be sensitizing and cause a delayed contact allergic dermatitis. The clinical scenarios associated with each type of artificial nail are summarized below.

Methacrylate Sculptured Nails
Methacrylate is commonly used to create artificial sculptured nails. Using a paper or Teflon nail form, the natural nail is painted with a fresh acrylic mixture that hardens at room temperature. The sculptured nail can be filed and manicured to shape. As the nail grows out, further applications of acrylic are added every few weeks to fill in the surface defect at the lunula. These sculptured nails may be used alone or over a tip. No ultraviolet (UV) curing is needed.

Allergic reactions due to methacrylate sculptured nails may occur 2-4 months and even as long as 16 months after the first application. The main symptom of an allergic reaction is pruritus in the nail bed. Paronychia can also be present and is associated with excruciating pain in the nail with occasional paresthesia. The nail bed is dry, thickened, and there is usually onycholysis. The natural nail plate thins, splits, and sometimes discolors. It takes several months for the nails to return to normal. Permanent nail loss is rare, as is intractable prolonged paresthesia. Associated symptoms include allergic contact dermatitis of the face and the eyelids as a result of touching the face with the hands. Acrylates are many times more likely to cause sensitization than methacrylates or stabilizers.

The majority of cases of nonallergic reactions result from physical trauma or abuse. After 2-4 months under a sculptured nail, damage to the natural nail is common. The edges of the sculptured nails will eventually become loose with continual wear. These edges must be clipped and then rebuilt to prevent the development of an environment prone to bacterial and candidal infection (beneath the nail plate). Infections are a result of improper application and maintenance. If filling of the sculptured nails is not performed every 2 weeks, then a lever arm will be created. The lever arm is a predisposition to traumatic onycholysis or damage to the natural nail.

If the natural nail becomes yellow or crumbles easily, then the product was applied and maintained incorrectly.

Another nonallergic reaction is due to primer, which is a strong irritant and may produce third-degree burns. Primer is hazardous if one floods the cuticles, neglects to clean up spills immediately, or ignores a complaint of the skin burning.

Onycholysis is very common with nail extensions. Thickening of the nail bed's keratin layer may sometimes involve the entire nail bed, sometimes with onycholysis. Since removal of acrylic nails requires filing, worn down (or over-filed) nails may result.

Gel Nails
Gel system products are premixed, either acrylic-based (14% of the US market) or cyanoacrylate-based (1% or less of the US market).

The nail is primed when required (rarely). Then, the gel is brushed on the nail (base coat, 2 polish coats, and top coat) and cured with UV light or LED light. Removal of gel polish is difficult, often taking 15 minutes after soaking in acetone.

Allergic reactions due to photobonded acrylate may lead to nail loss and paresthesia.

Other side effects may include shrinking of the gel enhancement product, which may result in lifting of the nail and cracking of the tip, or the patient may notice that the gel enhancement feels tight secondary to excessive shrinking. Other symptoms include throbbing or warmth below the nail plate as well as tender fingertips.

Preformed Artificial Nails
Plastic press-on nails are preformed and glued to the nail with cyanoacrylate preparation. They are packaged in several shapes and sizes to conform to normal nail plate configurations. They are used as full nails or nail tips and are fixed with a special adhesive that is supplied with the kit. Preformed nails in gold plate may be used in the same way as plastic nails. The application of preformed prosthetic nails is limited by the need for the presence of normal nail for attachment. Some manufacturers recommend that preformed artificial nails only be used for 1 or 2 days at a time. The use of artificial tips is the most common application of prosthetic nails.

Allergic reactions to preformed artificial nails (within 3 months) include painful paronychia, onychodystrophy, onychia, and discoloration of the nails due to cyanoacrylate nail preparations. These reactions may last for several months. Associated symptoms include allergic contact dermatitis of the eyelids.

Nonallergic reactions due to preformed artificial nails include onycholysis and nail surface damage. These reactions occur when the preformed nails stay in place for more than 3-4 days.