A black toenail can be alarming, but it’s often the result of a common issue: a bruise under the nail, known medically as a subungual hematoma. This typically occurs due to injury. However, it’s important to know that a black toenail can also signal other underlying conditions, ranging from fungal infections to vitamin deficiencies or even medical conditions like diabetes or, in rare cases, cancer.
While a black toenail might sometimes be painful, many cases resolve on their own over time. For those that require intervention, treatments are available, from over-the-counter remedies to prescription medications, and in certain situations, professional medical care.
Prevention is always better than cure. Taking proactive steps like wearing properly fitting shoes and maintaining good foot hygiene can significantly reduce your risk of developing black toenails.
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Black Toenail Symptoms
The most noticeable symptom of a black toenail is the change in nail color itself. While often appearing black, the discoloration can also present as reddish, purplish, or brownish depending on the stage and cause. Alongside color changes, you may experience other symptoms including:
- Toenail Pain: Varying from mild tenderness to sharp pain, depending on the underlying cause and severity.
- Nail Separation: Over time, the toenail may start to detach from the nail bed.
- Nail Thickening or Splitting: The texture and structure of the nail can change, becoming thicker or prone to splitting.
If an infection develops in the affected area, additional symptoms might emerge:
- Swelling: The skin around the toenail becomes puffy and inflamed.
- Odor: An unpleasant smell emanating from the toenail area.
- Redness: The skin surrounding the nail turns red, indicating inflammation.
- Discharge: Pus or fluid leaking from around the nail.
Sometimes, nail discoloration appears as vertical lines or streaks, known as striations or splinter hemorrhages. These are caused by bleeding from small blood vessels under the nail. It’s crucial to pay attention to any nail discoloration that is accompanied by pain or persists without improvement; these symptoms warrant evaluation by a healthcare professional.
Black Toenail Causes
Several factors can lead to toenail discoloration. The most prevalent causes of black toenails include:
- Bruising under the nail due to trauma or pressure
- Fungal nail infections
- Ingrown toenails
- Underlying health conditions
- Melanoma (rare)
- Medications
Bruise Under the Nail Due to Trauma or Pressure
Trauma is the most frequent culprit behind a black toenail. This trauma can be a result of a direct injury like stubbing your toe forcefully or dropping a heavy object on it. The impact causes blood vessels to break, and the trapped blood beneath the nail is what causes the dark discoloration. In these cases, the black toenail may eventually fall off as the new nail grows underneath, a process that can take several months, sometimes up to six months for complete regrowth.
What Is Runner’s Toe?
Runners and individuals who engage in frequent walking are particularly susceptible to “runner’s toe,” another form of subungual hematoma. This condition arises from the repetitive bumping or rubbing of the toes against the inside of the shoe during physical activity. Foot swelling during exercise can exacerbate this pressure. Runner’s toe commonly affects the second or third toes.
Shoes that are too tight or ill-fitting contribute significantly to this problem. They can compress the toes, causing direct trauma to the nail, or allow the foot to slide forward with each step, leading to repeated micro-trauma and subungual hematoma formation.
Fungal Nail Infection
Fungal nail infections, often caused by dermatophytes, are another common reason for toenail discoloration. These infections thrive in environments where there’s a break in the skin near the nail or in moist conditions, such as sweaty feet. Individuals with diabetes, vascular disease, or weakened immune systems are more prone to developing toenail fungus.
Ingrown Toenail
An ingrown toenail occurs when the edge of the toenail grows into the surrounding skin. This can lead to a bacterial infection, which in turn can cause discoloration of the nail.
Underlying Health Condition
Various underlying health conditions that affect circulation, such as diabetes, kidney disease, heart infections, psoriasis, or anemia, can manifest as discolored toenails. In individuals with diabetes, toenail discoloration often presents as a yellowish hue, but blackening can occur in some instances.
Vitamin deficiencies can also play a role. A vitamin B12 deficiency, for example, is known to cause black toenails, and fortunately, this discoloration is typically reversible with treatment.
Melanoma
In rare instances, a black toenail can be a sign of melanoma, a serious form of skin cancer. Subungual melanoma, a specific type that occurs under the nail, usually appears as a dark streak on the nail. While rare, it’s critical to diagnose and treat it promptly.
Medications
Certain medications can also induce toenail discoloration as a side effect. These medications can affect the nail bed, blood supply to the nail, or increase the skin’s sensitivity to light. Medications known to cause nail discoloration include:
- Cancer drugs, such as tyrosine kinase inhibitors and taxanes
- Antibiotics, including tetracycline and zidovudine (used to treat HIV)
- Retinoids, vitamin A derivatives used in skincare
- Psoralens, light-sensitive drugs for skin conditions like psoriasis
- Plaquenil (hydroxychloroquine), an antimalarial drug also used for autoimmune conditions
When to See a Healthcare Provider
If you are aware of a recent injury to your toenail, the pain is minimal, and less than half of the nail is black, medical intervention may not be necessary. However, it’s advisable to consult a healthcare provider if any of the following conditions are present:
- Persistent Toenail Pain: If the black toenail is causing significant or ongoing pain.
- Gradual Discoloration Onset: If the discoloration has appeared slowly without a known injury.
- Extensive Discoloration: If more than half of the toenail is black.
- Spread of Discoloration: If the discoloration extends beyond the nail to the surrounding skin.
- Bumps Under the Nail: If you notice any bumps or growths developing under the nail.
- Underlying Health Conditions: If you have pre-existing conditions like diabetes or vascular disease.
Spreading discoloration or bumps under the nail are particularly concerning and require prompt medical attention to rule out infection or, in rare cases, skin cancer. You can consult your primary care physician or a dermatologist for evaluation of a black toenail, especially if melanoma is suspected.
Complications
Potential complications from a black toenail can include permanent nail damage, leading to misshapen or thickened nail regrowth. Fungal infections, if left untreated, can spread to other toenails. In the rare event that the discoloration is due to melanoma, it carries the risk of spreading to other parts of the body if not addressed.
How Are Black Toenails Diagnosed?
Diagnosis typically starts with a physical examination of the toenail by a healthcare provider. They will inquire about recent injuries, physical activities, and footwear habits. Based on your symptoms, they might recommend tests to rule out underlying medical conditions that could be contributing to the black toenail.
If a fungal infection is suspected, the healthcare provider may take a small nail clipping sample and send it to a laboratory for analysis to identify the specific fungus and determine the most effective treatment.
How Do You Treat a Toenail That Has Turned Black?
If a black toenail is painless and involves less than half of the nail, treatment might not be required. The discoloration will typically resolve as the nail grows out. However, for black toenails caused by trauma covering more than half the nail, seeking medical evaluation is recommended to check for subungual lacerations (tears or cuts under the nail).
For painful black toenails due to swelling or pressure, home treatments can provide relief:
- Elevate your foot: Reduces swelling and pressure.
- Apply a cool compress: Helps to reduce pain and inflammation.
A healthcare provider can also treat a black toenail caused by trauma by creating small drainage holes in the nail to relieve pressure and drain trapped blood. This procedure is most effective if performed within two days of the injury. It is generally painless as the nail itself lacks nerve endings.
In cases where discoloration is extensive, the nail is separating from the nail bed, or the injury is severe, nail removal might be recommended by your healthcare provider. The area will be numbed to ensure a pain-free procedure.
For black toenails caused by fungal infections, treatment options include topical and oral antifungal medications. Over-the-counter (OTC) and prescription remedies are available, such as ointments and soaks.
Prescription topical medications include:
- Ciclopirox (Penlac)
- Efinaconazole (Jublia)
- Tavaborole (Kerydin)
Prescription oral medications include:
- Fluconazole (Diflucan)
- Griseofulvin (Grisactin)
- Itraconazole (Sporanox)
- Terbinafine (Lamisil)
Combination therapy with multiple medications might be necessary, and treatment durations can extend for months or even over a year as the nail grows out and the infection clears. The nail may grow back with a slightly different appearance.
If a bacterial or yeast infection is the cause, appropriate antibiotic or antifungal treatments will be prescribed, which may include ointments or oral medications.
In the rare instance of subungual melanoma, the primary treatment is usually surgical removal of the growth. If the melanoma has spread, further treatment options will be discussed with your healthcare provider.
Prevention
While not all causes of black toenails are preventable, particularly those resulting from sudden injuries, you can take preventive measures to lower your risk:
- Wear Properly Fitting Shoes: Ensure shoes have adequate toe box space to prevent pressure and trauma.
- Keep Feet Dry and Clean: Good foot hygiene reduces the risk of fungal infections.
- Avoid Open-Toed Sandals in Risky Environments: Protect your toes from injury, especially in work or outdoor settings.
- Protect Feet from Sun Exposure: Apply sunscreen to your feet, including toes, when exposed to sunlight.
- Proper Toenail Trimming: Cut toenails straight across to prevent ingrown toenails.
- Manage Underlying Conditions: If you have diabetes or other health conditions, ensure they are well-managed.
Summary
A black toenail is frequently caused by trauma leading to blood accumulation under the nail. Often, it resolves naturally as the nail grows out. However, other causes, including fungal infections, ingrown toenails, vitamin deficiencies, certain medications, and rarely, cancer, should be considered.
If you experience pain, gradual onset of discoloration, or spreading discoloration, seeking medical advice is crucial. Treatment options range from home care to prescription medications and, in some cases, medical procedures. Prevention through proper foot care and footwear is key to maintaining healthy toenails.
