There are several possible reasons why skin grows under the fingernail. You can pinpoint the cause by considering other symptoms and general nail care habits.

The hyponychium is the skin just under the free edge of your nail. It’s located just beyond the distal end of your nail bed, near your fingertip.

As a barrier from germs and debris, the hyponychium stops external substances from getting under your nails. The skin in this region contains white blood cells to help prevent infection.

But sometimes, the hyponychium can overgrow and become thicker. This can make trimming nails painful, and some people also don’t like how it looks.

In this article, we’ll cover the potential causes of overgrown skin under the fingernail and how to treat it.

Hyponychium thickening can affect one, some, or all the fingers. Possible symptoms include:

  • hyponychium attached to the nail as it grows
  • thick, pale skin under the nail
  • tenderness
  • pain, especially while trimming nails

Hyponychium overgrowth can have different causes.

Pterygium inversum unguis

Pterygium inversum unguis (PIU) occurs when the hyponychium attaches to the underside of the nail as it grows. It’s an uncommon condition but a common cause of skin overgrowth under the fingernail.

Scientists don’t fully understand PIU. However, they know it can be present from birth or acquired later.

The acquired form is most commonly associated with autoimmune conditions such as lupus but can also be triggered by external factors, such as exposure to gel polish, for example.

Psoriasis

Psoriasis is a skin condition where skin cells grow too quickly. It can affect any part of the body, including the nails.

Nail psoriasis involves many parts of the nail. In the hyponychium and nail bed, the skin cells grow excessively, causing scaling and buildup. This overgrowth is called subungual hyperkeratosis.

The skin underneath the nail might look:

  • thick
  • discolored
  • chalky

If the skin becomes very thick, it can cause onycholysis, which is the separation of the nail plate from the nail bed.

Fungal infection

Another possible cause is a fungal nail infection, also known as onychomycosis. This occurs when a fungus on the skin infects the fingernail. It can thicken both the nail and the skin tissue beneath it.

Other symptoms of a fungal nail infection include:

  • white or yellow-brownish discoloration
  • deformed nail shape
  • brittle, coarse nails
  • pits or indentations on the nails
  • lifted nail (due to thickened skin)

The most common form is distal and lateral subungual onychomycosis (DSLO). It starts in the hyponychium and then spreads to the nail plate and bed.

The most appropriate treatment depends on the cause. It may include:

  • Avoiding certain manicures: If gel manicures or acrylic nails are causing PIU, avoiding these procedures will usually reverse it. Consider switching to regular manicures.
  • Corticosteroids: A doctor can prescribe a topical corticosteroid if you have nail psoriasis. This treatment, which is applied to the nails, can help manage skin thickening.
  • Antifungal medication: The thick skin under the nail may improve if you have a fungal infection. Systemic (oral) medication is typically the most effective but has side effects.
  • Cuticle oil: Some people apply cuticle oil to soften the thickened skin.

If you’re unsure what’s causing skin growth under your nail, visit a dermatologist. This type of doctor specializes in skin and nails. The Healthline FindCare tool can provide options in your area if you don’t already have a doctor.

They can determine the best treatment by examining your nails and other symptoms.

Also, see a doctor if the skin is:

  • bleeding
  • painful
  • discolored
  • smelly
  • swollen

Be sure to consult a doctor instead of a nail technician. Nail technicians aren’t medically trained to treat nail conditions.

Is the hyponychium good or bad?

Then hyponychium is generally good because it protects your nail from harmful substances. However, it can become a problem if it overgrows, which can be painful and may increase the chance of infection.

Why do gel manicures cause hyponychium?

The reason gel manicures can trigger hyponychium thickening might be related to the chemicals in the gel, though isn’t fully proven.

What happens if I cut my hyponychium?

It’s not recommended to cut your hyponychium as this risks introducing an infection. If you’re concerned about overgrowth, see your doctor for an evaluation.

The hyponychium is the thick skin under your nail tip. It can overgrow and become even thicker, making it painful to trim your nails.

You’re more likely to have overgrown hyponychium if you get gel manicures, wear acrylic nails, or bite your nails. Nail psoriasis and fungal infections can also cause skin cells to accumulate under your fingernails.

It’s best to avoid picking at the skin. Instead, visit a dermatologist, especially if it’s bleeding, discolored, or swollen.