What Does the Skin Do? (7 Functions)
May 6, 2026
What does the skin do? (7 functions) The skin is far more than just the body’s outer covering; it is the largest and heaviest organ in the human body. Often referred to as the “integumenta...
This is an overview of 10 common finger and toenail conditions. But, let’s start with a definition.
What are Nails?
Nails are protective plates made of a hardened protein called keratin, covering the tips of our fingers and toes. They grow from an area beneath the skin called the nail matrix.
Their two main jobs are to safeguard the sensitive tissue of our digits from injury and to enhance our ability to grip, scrape, and feel fine textures.
What it is: A very common infection where microscopic fungi invade the nail, typically thriving in warm, damp environments like sweaty shoes.
Common signs: The nail becomes thickened, brittle, and discoloured (turning yellow, white, or brown), often crumbling at the edges.
When to Worry:
The infection spreads to multiple nails or surrounding skin
The thickness of the nail causes discomfort or pain when walking
When to See a Doctor:
Promptly if you have diabetes or a weakened immune system, as minor foot issues can quickly escalate into serious infections.
What it is: A skin infection around the edges of the nail, usually caused by bacteria entering through a tear in the cuticle, a hangnail, or from nail-biting.
Common signs: Sudden swelling, redness, warmth, and throbbing pain in the skin directly bordering the nail.
When to Worry:
A collection of pus (an abscess) forms under or beside the nail
The redness and swelling begin to spread rapidly down the digit
When to See a Doctor:
Promptly. Antibiotics or a minor procedure to drain the pus are often needed to clear the infection and prevent deeper tissue damage.
What it is: A painful condition where the sharp edge of the toenail grows sideways into the soft flesh of the toe, frequently caused by improper trimming or tight footwear.
Common signs: Intense pain along the side of the toe, accompanied by swelling, redness, and clear or bloody discharge.
When to Worry:
The toe becomes increasingly swollen, firm, or produces yellow pus
You experience a fever or spreading warmth up the foot
When to See a Doctor:
Soon. Early professional treatment can correct the growth pattern and prevent severe, deep-seated infections.
What it is: A collection of blood underneath the nail plate, almost always resulting from a direct crush injury or severe trauma to the digit.
Common signs: A dark red, purple, or black discoloration beneath the nail, accompanied by a throbbing, intense pain immediately following the injury.
When to Worry:
The pain is severe, constant, and unremitting after several hours
The nail bed becomes completely detached or significantly deformed
When to See a Doctor:
Urgently. A doctor can safely decompress the trapped blood to relieve the painful pressure or check for a broken bone underneath.
What it is: A structural weakness where the nail plate splits, peels, or breaks easily, often caused by frequent wetting and drying of the hands or harsh chemicals.
Common signs: Nails that are thin, easily frayed at the tips, or peel away in layers, making it difficult to grow them out.
When to Worry:
The brittleness is accompanied by severe thinning, pitting, or unusual ridges
Changes occur across all fingernails and toenails simultaneously without a clear cause
When to See a Doctor:
For a routine evaluation to rule out underlying systemic causes, such as thyroid conditions or nutritional deficiencies.
What it is: Deep, horizontal grooves or indentations running across the nail plate, occurring when nail growth is temporarily interrupted by a severe illness or stress.
Common signs: Visible, palpable transverse ridges that slowly move forward toward the tip as the nail naturally grows out.
When to Worry:
Multiple deep lines appear on almost every single nail
The lines show up without any history of recent illness, high fever, or physical trauma
When to See a Doctor:
Routinely. To confirm the cause and ensure there is no ongoing systemic issue or chronic nutritional imbalance affecting your health.
What it is: A chronic autoimmune condition that alters the skin cells, frequently targeting the nail matrix and causing significant structural changes.
Common signs: Small, distinct pits on the surface of the nail, yellowish “oil drop” discolouration under the plate, and loosening of the nail from its bed.
When to Worry:
Severe structural changes cause the nail to crumble or completely detach
The nail changes are accompanied by painful, swollen joints in the fingers or toes
When to See a Doctor:
Routinely. Specialist dermatological treatments can help manage the condition and protect the integrity of the nail matrix.
What it is: A physical change where the tissue beneath the nail plates thickens, causing the fingertips to enlarge and the nails to curve sharply downward.
Common signs: Tips of the fingers look bulbous, the nails feel soft or “sponge-like” when pressed, and they lose the normal angle where the nail meets the cuticle.
When to Worry:
Any noticeable flattening or rounding of the nails that develops gradually over months
Clubbing accompanied by shortness of breath, chronic cough, or chest pain
When to See a Doctor:
Soon. Clubbing is frequently a sign of an underlying medical condition involving the lungs or cardiovascular system that needs thorough investigation.
What it is: An increased amount of pigment within the nail plate, creating a distinctive brown or black vertical band running from the cuticle to the tip.
Common signs: A single or multiple vertical dark lines on the nail; can be entirely benign or a sign of something more serious.
When to Worry:
A single line becomes suddenly darker, wider, or changes its borders over time
The dark pigment spills over from the nail plate onto the surrounding skin of the cuticle
When to See a Doctor:
Soon. Any new or evolving dark stripe requires a professional assessment to definitively rule out subungual melanoma, a rare form of skin cancer.
What it is: The painless separation or lifting of the nail plate away from its underlying pink nail bed, starting from the tip and moving backward.
Common signs: The detached portion of the nail appears white, opaque, or yellowish, creating a large gap beneath the free edge.
When to Worry:
The separation extends deep into more than half of the nail bed
The gap underneath becomes painful, foul-smelling, or turns green (indicating a secondary bacterial infection)
When to See a Doctor:
Routinely. For confirmation of the cause and targeted treatment options to prevent permanent detachment or chronic infection.
Note. If accompanied with joint pain and morning stiffness in the fingers, there may be a rheumatological cause (i.e. it is part of a broader joint condition) – e.g. psoriatic arthritis.
Regular nail inspection – is vital for noticing early structural changes or subtle signs of systemic health issues.
Do not ignore rapidly spreading redness or pus – is a bacterial infection that requires prompt medical evaluation and potential antibiotics.
Most nail issues are benign and highly treatable – but early diagnosis is key to protecting the delicate nail bed and matrix.
Nail abnormalities are standard medical concerns – never let embarrassment delay a visit to the doctor or podiatrist.
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