Pain experienced when pressing on a fingernail or the surrounding skin is a common symptom. The nail unit, composed of the hard plate, soft tissue, and nerve endings, is highly sensitive to internal and external changes. A simple press can reveal underlying issues, ranging from immediate injury to a developing biological process. Understanding the specific nature of the pain helps determine its origin.
Acute Pain from Injury and Bruising
The most immediate cause of pressure-induced pain is acute physical trauma, such as a crush injury or blunt force impact. This type of injury frequently leads to a subungual hematoma, a collection of blood that pools in the confined space between the nail plate and the nail bed. The pain is a direct result of the increasing pressure exerted by this trapped blood against the densely innervated tissue underneath the unyielding nail.
This pressure causes an intense, throbbing sensation instantly aggravated by any external force. If the hematoma covers a significant portion of the nail—typically over 25%—the pressure buildup is substantial and often requires medical intervention. Drainage of the blood, a procedure called trephination, provides almost immediate relief by releasing the internal pressure.
Even without visible blood, a severe crush injury can damage the delicate soft tissues and nerve endings of the nail bed itself. Direct trauma causes immediate inflammation and swelling of the underlying tissue, which creates localized pressure against the nail plate. The subsequent pain upon pressing indicates localized tissue damage that has not yet resolved, often with associated tenderness in the distal phalanx bone beneath the nail.
Pain Caused by Infection and Swelling
Pain that develops slowly over several days and is accompanied by warmth often signals an infectious process, where swelling creates painful internal pressure. Paronychia is a frequent cause, involving a bacterial or fungal infection of the nail fold, the skin that frames the nail plate. Bacteria, such as Staphylococcus aureus, enter through a break in the skin, such as from a hangnail, aggressive cuticle trimming, or chronic moisture exposure.
The body’s immune response generates a collection of pus and inflammatory fluid directly beneath the skin or under the nail fold. This visible redness and swelling (edema) is highly painful because the accumulating fluid has nowhere to expand, causing the tissue to press against the rigid nail. Pressing on the area intensifies this discomfort by compressing the already inflamed tissues.
Acute paronychia, typically bacterial, develops rapidly and may present with a pus-filled blister or abscess that is tender to the touch. Chronic paronychia, often fungal, develops more slowly and may cause the nail to become detached or deformed over time. An ingrown nail (onychocryptosis) can also cause pressure pain when the nail edge penetrates the surrounding skin, leading to a localized inflammatory reaction and subsequent pressure.
Less Common Structural Causes of Pressure Pain
Occasionally, the cause of pressure-sensitive pain is a structural growth originating within the nail unit. Glomus tumors are a rare, benign type of soft tissue growth that forms from the glomus body, a specialized structure involved in temperature regulation. These tumors cause disproportionately severe, pinpoint pain localized to a specific area beneath the nail.
Unlike common bruising, the pain from a glomus tumor is often paroxysmal and intensely sensitive to cold temperatures. Pressing directly on the tumor can trigger a sharp, throbbing pain, even if the tumor is tiny.
Another potential structural cause is a myxoid cyst, a fluid-filled sac often associated with underlying osteoarthritis in the distal finger joint. While often painless, if the cyst develops over the nail matrix, the pressure from the growing sac can cause a characteristic longitudinal groove or dent in the nail plate. Pressing on the cyst can elicit tenderness due to the mechanical compression of the underlying structures.
When to Seek Professional Medical Care
While minor trauma and early-stage infections can often be managed with home care, certain symptoms warrant immediate professional evaluation. Seek medical attention if the pain is severe, throbbing, and persistent, particularly following a crush injury, as this may indicate a need for surgical decompression of a large subungual hematoma.
A doctor should also be consulted if signs of spreading infection are present. These include redness that extends beyond the immediate area, the development of red streaks traveling up the finger or arm, or the presence of fever and chills. These symptoms suggest the infection may be spreading into deeper tissues or the bloodstream.
Any unexplained, persistent, or recurring pain that lasts longer than two weeks should be evaluated. This is especially true if the pain is accompanied by cold sensitivity or a visible blue-red spot beneath the nail. Such chronic symptoms may indicate a glomus tumor or other underlying pathology requiring diagnostic imaging and specialized treatment.