Many individuals experience something growing beneath their toenail. This common phenomenon can appear as a thickened area or a separate layer. While alarming, understanding the underlying reasons helps demystify the situation. This article clarifies what might be happening, exploring its various causes and how it can be addressed.
Understanding the Phenomenon
What appears as a “nail growing under a nail” is a buildup of keratin, the nail protein, or other material beneath the existing nail plate. This condition is medically termed subungual hyperkeratosis, an excessive accumulation of keratin under the nail. It results in a thickened, often crumbly, and sometimes discolored layer that lifts the primary nail plate from its bed.
Its appearance varies based on the cause. It may appear as a white, yellow, or brownish substance pushing the nail upwards. The texture can range from soft and powdery to hard and dense. This buildup can also lead to changes in the overlying nail plate, causing it to thicken, become brittle, or even separate from the nail bed.
Common Causes
One frequent reason for this keratin buildup is a fungal infection, known as onychomycosis. Fungi thrive in warm, moist environments and can invade the nail. As the infection progresses, the body produces excess keratin as a defense, leading to thickening and debris. Associated symptoms can include nail discoloration, often yellow or brown, a crumbly texture, and sometimes a foul odor.
Trauma to the toenail is another common contributor. Trauma can be acute, such as stubbing a toe or dropping an object, injuring the nail matrix or bed. Such injuries disrupt normal nail growth, leading to irregular keratin production as the nail repairs itself. Chronic microtrauma, from ill-fitting shoes or repeated impact activities like running, also stimulates overproduction of nail cells and keratin. This constant pressure can damage the nail bed, prompting a protective thickening response.
Psoriasis, a chronic autoimmune skin condition, can also affect the nails, causing subungual hyperkeratosis. In nail psoriasis, the immune system attacks healthy nail cells, causing them to grow too quickly and pile up under the nail. This results in significant thickening and lifting of the nail. Other signs of nail psoriasis might include pitting, discoloration (often appearing as an “oil drop” or salmon patch), and crumbling of the nail plate.
Less Common or Underlying Contributors
Beyond the most common causes, several other conditions can contribute to subungual hyperkeratosis. Dermatological conditions like eczema or lichen planus can affect the nails. These conditions cause inflammation and abnormal cell turnover, extending to the nail unit and leading to thickening and buildup. The underlying mechanism often involves disrupted nail growth and keratinization.
Systemic diseases can also impact nail health, leading to thickening. Thyroid disorders, affecting metabolism and cell growth, can change nail structure. Peripheral artery disease, impairing circulation, can compromise nail health, making it prone to abnormal growth. These issues can weaken nail integrity, making it susceptible to other problems or causing primary nail changes.
Rarely, a mass or growth under the nail can mimic this appearance. This could be a benign tumor, like an exostosis (bony outgrowth), or a malignant tumor like squamous cell carcinoma. These growths occupy space, pushing the nail upwards and often causing localized thickening or discoloration. While uncommon, a healthcare professional would evaluate them during diagnosis.
Addressing the Issue
Diagnosing the cause of subungual hyperkeratosis begins with a physical examination by a healthcare professional. The doctor assesses the nail’s appearance, looks for symptoms, and inquires about medical history and lifestyle. To confirm diagnosis, especially for suspected fungal infection, a professional may take a nail clipping or scrape a sample from under the nail. This sample is sent to a laboratory for microscopic examination or fungal culture to identify the pathogen. If a bone spur or tumor is possible, imaging studies like an X-ray might be ordered.
Treatment approaches depend on the underlying cause. For fungal infections, antifungal medications are prescribed, either topical solutions or oral medications. Oral antifungals are more effective for severe infections but require monitoring for side effects. Debridement, trimming or filing down the thickened nail and buildup, can provide symptomatic relief and improve topical treatment efficacy.
For underlying skin conditions like psoriasis, treatment focuses on managing the dermatological issue. This may involve topical corticosteroids, vitamin D analogs, or systemic medications. In severe cases, or if a tumor or bone spur is confirmed, surgery may be necessary to remove the growth or address the abnormality. Self-treating subungual hyperkeratosis without a professional diagnosis is not recommended, as it can delay effective treatment and potentially worsen the condition.
Prevention and When to Seek Professional Help
Preventing subungual hyperkeratosis involves consistent foot and nail care. Maintaining good foot hygiene, including regularly washing and thoroughly drying feet, especially between the toes, helps deter fungal growth. Wearing properly fitting footwear that allows toes to move freely and avoids excessive pressure also prevents trauma. Trimming toenails straight across and not too short can reduce the risk of ingrown nails and associated trauma.
Managing underlying medical conditions like diabetes or psoriasis is also a preventive measure. Regular medical check-ups and adherence to prescribed treatments for systemic diseases help maintain overall nail health. If you notice persistent or worsening subungual hyperkeratosis, seek professional medical help. A doctor’s visit is important if the condition is painful, rapidly spreading, discolored, or does not improve with general care. A proper diagnosis ensures the most effective treatment plan.