Black toenails is an umbrella term for various levels of toenail discoloration, not only black but also brown or purple. The changed color can be on the nail itself or under it and is usually caused by dropping an object on the toe or injuring it in another way. Both a part of the nail or all of it can be affected and the unusual color is due to bleeding or blood clots appearing under its surface. In some cases, the hemorrhage causes very high pressure under the toenail and a lot of pain, especially when the entire nail is affected, and medical help might be needed.
The condition is also known as "runner's toe" when the second or third toenail becomes black. This is usually the effect of poor nail trimming, if the nail is too long, or a shoe that fits poorly and is too tight or too loose. Loose shoes that have a size bigger than the foot become a problem when descending, as the foot moves inside them and the nail can get damaged by hitting the toe box. Tight footwear will put pressure on nails and jam them, causing bleeding in the space between the nail plate and nail bed.
Malignant melanoma is another possible cause for black nails, which is rare but can be extremely dangerous. Like many other types of cancer, an early diagnosis can greatly improve the outcome and treatment options. To exclude the risk of melanoma, it is a good idea to seek medical advice if you have black toenails.
There are other possible causes of toenail discoloration, all of them quite rare, for example chronic ingrown nails or fungal infections. Black toenails can also be the side effect of a systemic disease.
In most cases, black toenails develop after damage to the nail. Nail trauma can be due to poor trimming, fungal infections, shoes that don't fit well or dropping heavy objects on the toes. When bleeding starts under the surface of the toes, their color changes. Sometimes the entire nail becomes black, or only a part of it. In medical terms, this is named "subungual hematoma", which just means blood under the nail.
Black nails are a common problem for athletes, in particular soccer players and hikers. A very common cause is wearing tight shoes that don't offer enough space for the longest toe. Every time the foot slides or the toe hits the edge of the shoe, the resulting pressure causes blood to build up under the nail. This happens when kicking or just walking and can be prevented by wearing special socks that stop sliding.
Ingrown toenails are another possible cause for black toenails and can be prevented by trimming them moderately long in a straight line across. Nails become ingrown if their edges penetrate the surrounding skin and get covered by skin folds as the nail grows. The nails ends up hurting the skin, causing bleeding and infections that turn it black. This can also be caused by tight shoes.
Onychomycosis, which is a fungal infection, can also turn nails black. It can be a mild condition at first, when the only symptoms are small white spots, but it later expands and makes the toenail grow very thick, with a yellow color. Just like in the other situations, the most common cause is poor fitting shoes that rub the nail and allow the bacteria in foot to penetrate it. It can be a painful condition due to pressure and inflammation and usually affects the big toe.
Fungal infestation most commonly affects athletes, since their feet are always warm and sweaty. People with a poor immune system, such as diabetes patients or elders, also have a higher risk. Antifungal drugs available without a prescription are usually enough to treat minor cases of infection. Topical antifungals can be prescribed by a doctor and are a better option for diabetics, despite their higher cost. Severe infections or recurrent ones can be eliminated by laser therapy, which kills the fungal cells.
Most cases of black toenails are harmless and don't require any treatment. If the condition is really painful and hampers walking, the liquid under the nail can be drained or the entire nail removed, in very severe cases. The most common outcome is that our body repairs the damage and a new toenail grows as the black one falls off.
A form of cancer named melanoma can also cause discoloured toenails but this is rare. If detected early, the tumour can usually be treated successfully. A normal black spot caused by injury will always advance with the nail as it grows. If this does not happen and there is no fungal infection, you should ask for medical advice, especially from a podiatrist. A biopsy is sometimes needed to confirm the diagnosis.
The main symptom of a black toenail is the change in color, which isn't always black. Despite the name of this condition, the nail can also turn purple, red or brown. Other possible symptoms are a bad smell, pain or the leakage of a fluid from under the nail.
Many symptoms are possible but in some cases none of them is reported and only nail discoloration can be detected. Additional symptoms are possible when the nail becomes infected, causing inflammation, redness, pain, odour and swelling.
The build-up of blood under the nail pushes the nail up and it eventually detaches it completely. In most situations, the nail becomes loose and falls off after a few days.
If black nails are the result of mild injury, as it happens in the majority of cases, no treatment is required because the nail will heal on its own. As a new nail grows to replace the damaged one, the black nail will eventually fall. However, you can always ask for the advice of a podiatrist if you want to be safe. They are specialized doctors who can evaluate the cause of the condition and prescribe a treatment, if necessary.
In most cases, your doctor will simply tell you that no medication or procedure is needed and advise you to let the nail heal on its own. If he suspects a serious problem, the podiatrist can remove the nail in order to examine the nail bed, after applying a local anesthetic.
Depending on the root cause and symptoms, several types of treatment are available. Lacerations must be washed and sometimes sealed by suturing. Hematomas cause pressure and pain in the area, so they must be removed. This can be done in three ways. The most common technique is to simply remove the entire nail and clean the hematoma under it. This sometimes requires for a protective barrier to be applied on the nail bed. Another option is to use a needle with a large gauge to puncture the nail and drain the fluid inside the hematoma. Finally, cautery uses an electrical device to burn a hole in the nail and allow the blood to flow out, eliminating the hematoma.
If the nail has been holed, the breach will remain on it for some time, because of the slow rate of growth of toenails. Discoloured toenails should regenerate normally, but this is not a given.
Podiatrists can help your toenail regain its health and initial color, especially if the condition is treated as early as possible. The treatment usually requires two visits to the doctor's office, about one week apart.
One simple home treatment that can be recommended by your podiatrist is to add some Epsom salt in lukewarm water and soak your foot in it for 10 to 15 minutes twice per day. Apply a topical antibiotic and a sterile bandage afterwards.
Toenails grow very slowly, with an average of no more than 3 mm per month, so a black nail will need several months to completely recover. However, the exact time depends on the type and degree of injury. The choice of treatment is also important, as well as your body's response to it.