Why Are My Toenails Red? Causes and When to Worry

Red discoloration on a toenail is almost always caused by blood trapped under or around the nail, and the most common culprit is simple physical trauma. But the range of possibilities is wide, from a bruise that will grow out on its own to an infection, a skin disease like psoriasis, or even a rare tumor. The shade, pattern, and location of the redness matter quite a bit when sorting harmless from worrisome, and the distinction between a red blotch, a thin red line, and a reddened half-moon near the cuticle can point to very different causes.

Trauma and Subungual Hematoma

The most frequent reason for a toenail to turn red, purple, or dark is a subungual hematoma, which is blood pooling between the nail plate and the nail bed underneath. This happens after a direct blow, like stubbing your toe or dropping something on it, or from repetitive low-grade pressure like running in shoes that are too tight. Runners and hikers know this well. The injury ruptures tiny blood vessels under the nail, and the blood collects with nowhere to go.

A fresh subungual hematoma often looks reddish at first and then darkens to purple, blue-black, or brown over days and weeks. A dermoscopic study of 47 subungual hematomas found that about half appeared purple-black, roughly a quarter had a blue-white hue, and about one in five showed a whitish granular pattern on top of the discoloration. All had a homogeneous color spread rather than irregular streaking, which helps distinguish them from more concerning conditions.

A small hematoma usually resolves on its own as the nail grows out. The discolored patch stays attached to the underside of the nail and slowly moves toward the tip over months. If the blood collection is large and painful, a doctor can relieve the pressure by making a small hole in the nail. The key thing to watch is whether the discoloration tracks forward with nail growth. A spot that stays in the same place instead of migrating toward the tip is not behaving like a hematoma and should be evaluated further.

Splinter Hemorrhages

Splinter hemorrhages are thin, dark red or brownish lines that run along the length of the nail, looking almost like tiny splinters embedded under the surface. They form when blood leaks out of the small vessels that run lengthwise through the nail bed. The blood sticks to the underside of the nail plate and creeps forward as the nail grows.

The most common cause is, again, trauma. A single bang or repeated friction can burst a capillary. But splinter hemorrhages also show up in a surprisingly long list of other conditions. Systemic illnesses like bacterial endocarditis (an infection of the heart valves) and diabetes can produce them, as can skin diseases including psoriasis and fungal nail infections. Certain medications, particularly some antibiotics and cancer drugs, have been linked to them as well.

A single splinter hemorrhage on one toe that appeared after you wore tight shoes is almost certainly mechanical and harmless. Multiple splinter hemorrhages across several nails, especially if you have not injured any of them, are a different story and worth mentioning to a doctor. In that scenario the hemorrhages may be a clue to something happening inside the body rather than at the nail itself.

Infections and Ingrown Toenails

Redness around or under the toenail sometimes comes from infection rather than bleeding. Paronychia is an infection of the skin fold alongside the nail. It typically follows a break in the skin, such as from an ingrown nail edge, an aggressive pedicure, or habitual picking at the cuticle. The tissue around the nail becomes red, swollen, and tender, and sometimes a small pus-filled pocket develops. Acute paronychia comes on quickly and usually clears within a few weeks with proper care; chronic paronychia lingers for six weeks or more and often involves different organisms.

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Ingrown toenails are one of the most common triggers for paronychia. When the nail edge curves into the surrounding skin, it can break the surface, let bacteria in, and cause a red, angry flare of tissue. In some cases, the body responds by forming granulation tissue, a bumpy, red, fleshy growth at the nail edge that bleeds easily. This looks alarming but is not cancerous. Treatment usually involves freeing the ingrown portion of the nail and managing the infection, sometimes with a minor office procedure.

If you notice redness concentrated along the side of the toenail rather than under the nail plate itself, an ingrown nail or early paronychia is high on the list. Soaking the toe, wearing open-toed shoes, and avoiding further irritation sometimes resolve mild cases. Spreading redness, increasing pain, or visible pus means it is time for professional treatment.

Psoriasis and Lichen Planus

Skin diseases that affect the rest of the body can also target the nails, and both psoriasis and lichen planus produce changes that include redness. Nail bed psoriasis often shows up as “oil drop” spots, also called salmon patches, which look like reddish-brown or yellowish-red discolorations under the nail. These patches get their name because they resemble a drop of oil seen through the translucent nail. Other nail bed signs of psoriasis include the nail lifting off its bed, thickening of the tissue under the nail, and splinter hemorrhages.

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Lichen planus, an inflammatory condition driven by the immune system, affects nails differently. In a study of 81 patients with nail lichen planus, the most frequent findings involved the nail matrix (the growth center under the cuticle). Longitudinal ridging, splitting, and thinning of the nail were the most common features. About 30% of patients had erythronychia, meaning red streaks on the nail, and roughly 12% had a red-colored lunula. Late-stage disease sometimes led to scarring that permanently destroyed part of the nail.

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If you already have psoriasis on your skin or scalp, nail involvement is common and does not necessarily mean the disease is worsening. But nail changes are sometimes the first sign of psoriasis or lichen planus, appearing before any skin patches develop. A nail that gradually becomes ridged, pitted, or discolored with red streaks over months, without any clear injury, is worth showing to a dermatologist.

What a Red Lunula Can Mean

The lunula is the pale half-moon shape at the base of the nail, just above the cuticle. Normally it is whitish or slightly pink. When the lunula turns distinctly red, the change stands out clearly against the rest of the nail and can be unsettling. Red lunula is considered uncommon, but it has been documented in connection with a number of systemic conditions including heart disease, liver disease, blood disorders, connective tissue diseases, and certain skin conditions.

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Not every red lunula indicates serious illness. Sometimes a local issue at the nail matrix is responsible, and the change can be isolated to just one or two nails. But when the lunulae across multiple fingers or toes turn red, and especially when the change persists, clinicians generally consider it a prompt to screen for underlying systemic problems. Red lunulae have also been reported in lichen planus affecting the nails, as noted in the study described above.

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A red lunula is subtle enough that many people never notice it unless they look carefully. If you spot it, pay attention to whether it is on one nail or many, and whether it persists for weeks. On its own it is not an emergency, but it is one of those quiet signs that a doctor can use to guide further evaluation.

Red Streaks Running Down the Nail

A narrow red band running from the base of the nail to the tip is called longitudinal erythronychia. This pattern is distinct from splinter hemorrhages, which are short, broken lines. Longitudinal erythronychia forms a continuous red streak through the full length of the nail and tends to persist rather than growing out.

The significance depends heavily on how many nails are affected. When a single nail has a red streak, the cause is most often a benign growth underneath the nail bed, though less commonly it can indicate a malignancy. When multiple nails have red streaks, the cause is more likely a systemic or regional disease such as lichen planus or Darier disease, a genetic skin condition.

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Because a single persistent red streak can occasionally be the first visible sign of a subungual tumor, dermatologists take localized longitudinal erythronychia seriously. If you notice one nail developing a red line that has been there for more than a couple of months and was not triggered by obvious injury, a dermatology consultation is reasonable. This is one situation where a small, undramatic change can carry disproportionate clinical weight.

Nail Tumors That Can Look Red

Several types of tumors, both benign and malignant, can grow under the toenail and present with redness as a prominent feature.

Among benign growths, glomus tumors are one of the better-known culprits. These small vascular tumors arise from the glomus body, a structure involved in temperature regulation in the fingertips and toes. They tend to be tiny (often around half a centimeter) but extremely painful, especially in response to cold or pressure. On imaging, they show up as highly vascular little nodules under the nail bed. Treatment involves surgical removal, and symptoms usually resolve completely afterward.

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Malignant tumors of the nail unit are rare but do occur. Squamous cell carcinoma of the nail can produce redness and lifting of the nail from its bed, and in advanced stages, ulceration.

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These tumors grow slowly and are often misdiagnosed for years as a wart, a fungal infection, or chronic paronychia. Subungual melanoma is another possibility. While melanoma is usually associated with dark pigmentation, amelanotic melanoma lacks the dark color and can appear as a reddish, fleshy mass under or around the nail. A case report described a patient whose amelanotic melanoma was initially diagnosed as a fungal nail infection based on biopsy-confirmed fungal elements. Only when the nail plate eventually fell off did the underlying red, friable tissue lead to the correct diagnosis.

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The lesson from these cases is that a nail condition that does not respond to treatment as expected, or that keeps changing over months and years, deserves a second look. A “stubborn fungal infection” or a “chronic ingrown nail” that never quite resolves is occasionally hiding something else underneath. Clinicians who see persistent nail dystrophy often recommend biopsy when the clinical picture does not add up, and that caution is well justified.

Chilblains and Blood Vessel Changes

Toes can turn red from vascular causes that have nothing to do with the nail itself. Chilblains, also called pernio, are painful, red-to-purple swellings that develop after exposure to cold and damp conditions. They appear on the toes, sometimes extending to the skin around the nails, and can make it look like the toenails themselves are red when the surrounding tissue is what is inflamed.

During the early phase of the COVID-19 pandemic, a wave of “COVID toes” drew widespread attention. Adolescents and young adults developed chilblain-like lesions on their toes, often without other COVID symptoms. Biopsy of affected tissue showed remodeling of the blood vessels in the skin, with thickened vessel walls and a mild immune-cell response around them. Interestingly, in many cases SARS-CoV-2 infection could not be confirmed by either molecular or antibody testing, leaving the exact trigger debated.

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Beyond chilblains, changes in the tiny blood vessels around the nail fold can signal systemic vascular diseases. Nailfold capillaroscopy, a technique where a clinician or researcher looks at the capillaries along the base of the nail with a magnifying instrument, can detect dilated, twisted, or disappearing capillaries. In patients with vasculitis, for example, dilated capillaries and areas where capillaries had dropped out were significantly more common than in healthy controls. These capillary changes correlated with the severity of the disease, including kidney involvement.

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For most people, red toes in cold weather are simply the body’s exaggerated response to temperature changes. Keeping feet warm and dry, avoiding rapid rewarming, and wearing appropriate footwear usually prevents chilblains. Persistent or recurrent episodes, especially in warm weather, may hint at an underlying circulatory issue worth investigating.

Congenital and Genetic Conditions

Rarely, red changes in the toenails are related to genetic conditions rather than acquired disease. Tuberous sclerosis complex, a condition that causes benign growths in multiple organs, can produce distinctive nail findings. Among them are splinter hemorrhages, dilated capillaries in the nail bed that create a characteristic “red comet” appearance on close inspection, and white longitudinal streaks.

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These findings are usually identified in the context of a broader evaluation for the underlying genetic condition. If tuberous sclerosis is already known, nail changes fit the picture. If it is not known, isolated nail redness would rarely be the clue that leads to diagnosis, since the condition almost always produces more obvious signs elsewhere in the body first.

Signs That Call for a Professional Look

Sorting red toenails into “wait and watch” versus “get it checked” comes down to a handful of practical signals. The following patterns generally warrant a visit to a doctor or dermatologist:

No clear injury: Redness that appeared without trauma, tight shoes, or any identifiable cause makes non-traumatic explanations more likely.
Persistence: A subungual hematoma should migrate toward the nail tip as the nail grows, which takes roughly six to nine months for a toenail. If the red or dark area stays in the same spot, it may not be a hematoma.
Multiple nails affected: Redness across several toenails, or toenails and fingernails together, raises the possibility of a systemic or inflammatory condition.
A single persistent red streak: A continuous red line running the full length of one nail, present for more than a couple of months, should be evaluated because of its association with subungual growths.
Spreading redness and pain: Red, swollen, increasingly painful skin around the nail that worsens over days suggests an infection that may need treatment.
A non-healing lesion: Any mass, bump, or area of tissue under the nail that bleeds easily, does not respond to treatment for a presumed infection, or keeps recurring should be biopsied.

It is worth knowing that doctors often examine nails with a dermatoscope, a handheld magnifying device with a light source, to distinguish between blood under the nail and pigmented lesions. The homogeneous color pattern of a hematoma looks different from the irregular streaking or variegation seen in tumors. If there is any doubt after dermoscopy, a nail biopsy gives a definitive answer. The procedure is less dramatic than it sounds: usually performed under local anesthesia in an office, with the nail growing back afterward.

Nailfold Redness Versus Nail Bed Redness

One source of confusion worth clearing up is whether the redness you are seeing is actually on or under the nail plate, or instead in the soft tissue fold surrounding the nail. These are different anatomical zones with different implications. Redness of the nail fold, the strip of skin bordering the nail on three sides, usually points to an infection like paronychia, an ingrown edge, or an inflammatory condition. Redness visible through the nail itself, whether as a uniform color change, a streak, or a spot, points to processes happening in the nail bed or matrix beneath.

The distinction matters because treatments differ. Paronychia calls for soaks, sometimes antibiotics or antifungals, and occasionally drainage. A subungual hematoma might need decompression if painful but otherwise just grows out. A persistent red streak under the nail might need imaging or biopsy. Taking a moment to identify where exactly the redness is concentrated can help you communicate more precisely with a healthcare provider and helps them narrow the possibilities faster.

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