Discomfort in the fingers or toes originating from the nail unit is medically termed onychalgia. This localized pain often feels disproportionate to the nail’s small size, signaling that something is amiss in the nail bed, matrix, or surrounding folds. While the symptom can be fleeting and minor, caused by simple daily accidents, persistent or escalating pain requires investigation to determine the underlying biological or mechanical disruption.
Mechanical Causes and External Pressure
Physical force is the most common cause of onychalgia. Severe trauma, such as crushing a finger, commonly results in a subungual hematoma, where blood vessels beneath the nail plate rupture and pool. This trapped blood causes intense, throbbing pain due to pressure buildup against the rigid nail plate and the nail bed.
Ingrown toenails (Onychocryptosis) generate pain as the nail plate edge grows into the surrounding skin fold, causing inflammation and tenderness. Repetitive micro-trauma, often seen in runners wearing ill-fitting shoes, forces the nail to repeatedly collide with the inside of the shoe. This continuous stress can lead to the nail lifting from the nail bed (onycholysis) or cause pain through the development of calluses under the nail. Aggressive cosmetic practices, such as scraping the nail bed during manicuring or improper removal of artificial enhancements, can also injure the nail matrix.
Common Nail and Skin Infections
Pain that is throbbing, warm, and associated with visible swelling often points toward an infection. The most frequent bacterial infection is Paronychia, which affects the skin folds surrounding the nail, typically the lateral or proximal folds. Bacteria, often Staphylococcus aureus, gain entry through minor breaks in the skin barrier, such as those caused by hangnails, nail-biting, or overly aggressive cuticle trimming. This results in a rapid onset of inflammation and pus formation, which creates significant pressure and localized pain.
Fungal infections, primarily Onychomycosis, do not usually cause acute pain but can lead to chronic discomfort as the condition progresses. The fungi cause the nail to become thickened, brittle, and discolored, often yellow or white. This thickening creates pressure against the nail bed, which causes aching pain, especially when wearing shoes. Though less common, viral infections like herpetic whitlow also cause pain, presenting as clusters of small, fluid-filled blisters on the fingertip, often accompanied by a burning sensation before the lesions erupt.
Pain Linked to Systemic or Chronic Illnesses
The nail unit can reflect internal health issues, with certain systemic or chronic illnesses manifesting as painful nail symptoms. Inflammatory conditions like Nail Psoriasis can cause pitting, ridging, and separation of the nail from the bed, which leads to tenderness and discomfort. Up to 80% of individuals with Psoriatic Arthritis may develop these nail lesions, where the pain is linked to the underlying autoimmune inflammation.
A Glomus Tumor, a rare, benign growth of the glomus body, can also cause pain. These tumors cause paroxysmal pain that is often triggered by changes in temperature, especially cold exposure. Conditions affecting circulation, such as diabetes or peripheral vascular disease, can compromise nail health, making the nail unit more susceptible to trauma and infection.
Identifying When Medical Attention is Necessary
While many causes of onychalgia resolve with simple home care, certain signs suggest the need for professional medical evaluation. Persistent pain that does not improve after 7 to 10 days of at-home treatment should be investigated to rule out underlying chronic issues. Immediate attention is necessary if the pain is accompanied by signs of a spreading infection, such as fever, red streaking extending up the limb, or a severe, throbbing pain that disrupts sleep.
A subungual hematoma covering more than 25% of the nail plate, or one causing intense pressure, may require drainage by a physician to relieve pain and prevent permanent nail damage. Individuals with conditions that impair circulation or healing, such as diabetes or immune deficiencies, should consult a doctor promptly for any nail injury or infection. Unexplained changes in nail color, shape, or a localized, pinpoint tenderness that is highly sensitive to cold are also reasons to seek a professional diagnosis.