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 nail. 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 it painful to trim your nails. 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 nail as it grows
- thick, pale skin under nail
- pain, especially while trimming nails
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.
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 it’s a common cause of skin overgrowth under the fingernail.
Scientists don’t fully understand PIU. However, they do know it can be present from birth or acquired later. The acquired form is associated with:
- injury or trauma to the nail
- contact dermatitis
- frequent gel manicures
- wearing acrylic nails for long periods of time
- using nail hardeners
- nail biting
Acquired PIU may also be seen in conditions like:
- subungual exostosis (bony overgrowth on fingertip)
- systemic sclerosis
- neurofibromatosis (tumors on nerve tissue)
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:
If the skin becomes very thick, it can cause onycholysis, which is separation of the nail plate from the nail bed.
Another possible cause is a fungal nail infection, also known as onychomycosis. It occurs when a fungus on your skin infects the fingernail. It can thicken both the nail and skin tissue beneath the nail.
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 nail 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. If you have a fungal infection, the thick skin under the nail may get better with antifungal medication. Typically, systemic (oral) medicine is most effective, but it does come with side effects.
- Cuticle oil. Some people apply cuticle oil to try to soften the thickened skin.
If you’re not sure 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:
Be sure to consult a doctor instead of a nail technician. Nail technicians aren’t medically trained to treat nail conditions.
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.