A black spot on a nail can be a cause for concern for anyone. Quite often, such a visual change appears without any accompanying symptoms and becomes an accidental finding. No one will be happy to see dark spots or streaks on their nails.
Sometimes the cause of this situation is traumatic injury. Then you can clearly indicate the factor that led to the visual defect. However, if there is no precise understanding of the cause of the corresponding symptom, you need to consult a doctor in order to find out why black spots appear on the nails in a particular case.
Hand nails are a kind of mirror of the body. They can tell a lot about a person, his lifestyle, and the presence of certain diseases. If a black spot appears on the fingernail, this may be evidence of a number of pathological conditions that often require appropriate treatment.
The most common causes of the corresponding symptom remain:
Black spots under the fingernails in this case arise due to blockage of such vessels. They can be not only dark, but also red. They often visually resemble small splinters.
Another serious disease that can cause a black spot under the nail is melanoma. This is the most dangerous tumor, requiring immediate initiation of appropriate therapy. If darkening of the nail plate occurs, you should definitely consult a doctor to exclude this diagnosis.
Sometimes black spots appear under extended nails. The reason for this may be a violation of the manicure procedure, the use of low-quality materials to cover the nail plates, or improper care for them. In this case, you just need to stop all such manipulations for a while and let your nails “rest.”
If the fingers more often indicate the presence of some kind of disease inside the body, then the situation when a black spot appears on the toenail is mainly associated with the influence of an external factor.
The traditional cause of such a visual defect remains traumatic injury with the formation of a hematoma. In cases of severe pain, doctors recommend trephination of the nail, which involves removing accumulated blood and reducing compression.
In addition, you need to remember the symptom of melanonychia. It will help explain why black spots on toenails look like straight lines running across the entire surface of the plate. In this case, pathological deposition of the melanin pigment occurs. This condition requires careful diagnosis, as it may be a sign of a serious illness. The most common reasons for this situation are:
In any case, if black spots appear on your toenails, you should consult a doctor to determine the exact cause and select the appropriate treatment (if necessary).
One of the situations when you shouldn’t worry is the presence of persistent pigmentation, which has been present at a certain point under the nail since birth. If such a pigmented formation (most often a mole) does not change shape, size and color, then there is no need to panic again. However, you should definitely consult a doctor to rule out all other diagnoses.
It is a qualified doctor who will tell you what to do if a black spot on the nail appears unexpectedly or causes some discomfort. In this case, it is important to avoid self-medication and follow the doctor’s recommendations to prevent a deterioration in the general condition.
Well-groomed and neat hands are the key to success, aesthetics and a mirror of the soul. This is our life, nutrition, care and beauty that needs to be maintained. What do healthy nails usually look like? They shine, show a pleasant pink color, are durable and strong to the touch.
If at least some of these descriptions of your nails do not match, then you should think about the fact that your nail plate does not quite fit the description of a “healthy nail.” Most likely, there is a disease that needs to be dealt with urgently, otherwise it will be too late. So, one of the common deviations is black spots on the nails of the thumb.
If you have such unpleasant spots, then you have significant health problems, perhaps a violation of the body system, which must be corrected immediately. So, the pathology of nails can vary widely in different colors. Let's look at the most common options:
In general, for half of the people who have already encountered the problem of black spots on the nails of their thumbs, the main reason for their manifestation is associated with a fungal infection, which simply damaged and literally “ate” the nail plate, worsening the condition of the skin and overall health.
If you consult a doctor in time, you can easily cure your nails and improve your condition. By the way, an unpleasant black spot also happens on the legs, so it’s not only the fingers that suffer because of such “patterns.” So, when many people, for example, walk in the same shoes for too long. Then you need to be extremely careful - black spots may well form on your big toe. In this case, the best way is to simply change your shoes to reduce toe injury. It’s a pity that you can’t change your shoes by hand so that everything would be so easy and simple.
Did you know that by the shape and location of black spots you can determine exactly what health problems are associated with them?
Another point that you need to know: bruises do not just appear, which means that you need to urgently consult a doctor. This is relevant if you notice that there were no bruises, but there is still blood inside the nail. Most likely, this is a glomus tumor - it is extremely forbidden to mess around with it, because it can only be removed by surgery. Do not allow it to grow under any circumstances!
And although self-medication is good, since only you and no one else takes care of yourself, it is best if you are examined by a doctor, since in 90% of cases the doctor is right, and all the medications prescribed by him are 95% suitable for patients. Also, if you have cracking skin in the nail area, the condition of your hands themselves is not very good and stable, there are stains on your nails, then you may simply not be very good about yourself and your hygiene, thinking that washing your hands or smearing them with cream – useless and not that important.
Remember that daily hand care will give you a reason to rejoice, feel beautiful and well-groomed. Taking care of yourself and prohibiting bad habits are two of the most important conditions-factors that stand at the forefront of everything else to make your nails look aesthetically pleasing and perfect.
Here's what you should follow to take proper care of your nails and hands:
Just don’t become an overly suspicious person. If spots appear, then you should not immediately think that you have cancer and panic without confirming these facts. All of the above is just an assumption that still needs to be proven by special inspection and analysis. Black spots and their bright or faint shade do not mean that the disease is progressing. This will just be another food for thought that you should still visit doctors more often than you do.
A simple reminder about identifying a problem on your nails:
Black spots on nails are not the most pleasant moment that can happen to a person. But in order not to procrastinate and injure yourself in the future, it is best to take care of yourself and always adhere to certain hygiene standards. Be careful and careful with your nails!
Black spots on the surface of the nail are not uncommon. They may be a sign of injury to the nail plate, an infection, or a general health condition. Otherwise, these spots are considered a cosmetic problem rather than a medical problem.
For most people they are unsightly and embarrassing.
Bruising is a common cause of stains on the nails. The injury causes blood to pool in the tissue beneath the surface of the nail plate. In medical terms, this is called a subungual hematoma. A common symptom of this condition is a change in the color of the nail plate.
Toenail injuries can cause pain and discomfort. It can be caused by running or walking, or by wearing tight shoes. In this case, the dark spot is caused by damage to the capillaries under the nail.
It is necessary to trim your nails and wear well-fitting shoes to prevent such injuries. In this situation, painkillers as well as a simple cold compress can help relieve temporary pain.
If the injury is severe, a person may lose a nail, however, there should be no dark spots when a new one grows.
Fungal infection is the other most likely cause of nail discoloration or blemishes. Fungus often occurs when toenails crumble. The most effective way to get rid of it is to take a course of antifungal medications.
A fungal infection can manifest itself as follows:
Bacterial infection can also cause black spots. In some people, it causes the nail plate to turn green. Pseudomonas aeruginosa (Pseudomonas) is a bacterium that causes the nail to turn green-black. Bacterial infection is common under loose nails.
To treat it at home, you can try applying antibiotic drops or soaking in an antiseptic solution such as vinegar. If the cause of the discoloration is a bacterial infection, you should:
This is a common type of injury seen in athletes. Also called a subungual hematoma, it results from a collection of blood under the nail. It is not a serious condition, but can be very painful.
A hematoma is caused by downward pressure or horizontal separation of the nail plate from the bed. This repetitive trauma results in bleeding and pooling of blood and is usually characterized by a reddish-black color to the toenail. In some people, the plate may also become thicker and more brittle.
Subungual hematoma is treated by conservatively reducing pressure in the affected area or by puncture and drainage. Another treatment option for more severe conditions is to remove the entire nail plate.
An ingrown toenail is also a possible cause of darkening, according to the American College of Foot and Ankle Surgeons.
Jaundice is a medical term that describes the yellowing of the skin. Jaundice itself is not a disease, but rather a symptom of various possible underlying conditions in the body. The color change occurs when the body has too much bilirubin, a yellow pigment formed when dead red blood cells are broken down in the liver.
Wearing shoes for a long time promotes the growth of bacteria and fungi. For example, athlete's foot occurs when shingles develops. You can become infected with the fungus through direct contact with an infected person or with contaminated surfaces.
When the cause of black spots on the nails is athlete's foot caused by heat exposure, other symptoms include the following:
Also known as primary adrenal insufficiency or hypofunction, Addison's disease is a rare disorder of the adrenal glands (two small glands that are located on the surface of the kidneys).
The adrenal glands produce two important hormones: cortisol and aldosterone. The disease can affect people of all ages, but is more common in people aged 30 to 50 years. According to the United Kingdom's National Health Services, the condition is more common in women than men.
In developing countries, the disease is often associated with autoimmune disorders as well as tuberculosis.
According to a study by the United States National Institutes of Health, Addison's disease is commonly associated with dysphagia, fatigue, weight loss, hypotension, abdominal pain, and brittle nails. This condition is classically considered to have hyperpigmentation due to ACTH melanogenesis.
You should seek medical help if you notice any of the following symptoms:
Psoriasis is a nail disease that affects approximately 2-3% of people. In psoriasis, too many skin cells are produced, which form colored spots, ulcers, and painful fluid-filled blisters.
Healthline reports that about half of people with psoriasis and about 80 percent of people with psoriatic arthritis develop changes in their nails. Currently, doctors cannot identify the cause of this phenomenon.
In rare cases, the nails are the only part of the body where signs of the disease appear. Some people may also develop an itchy rash on other parts of the body.
Psoriasis is accompanied by the following symptoms:
Treating this condition can be difficult because it affects the nail as it grows. Treatment options include the following:
Black spots under the nail can also be caused by skin cancer. Acral lentiginous melanoma is a type of cancer that can cause discoloration of the nails. Subungual melanoma begins in the nail matrix. Most often it affects the big fingers and toes. This rare type of skin cancer, like other melanomas, is associated with sun exposure. This disease requires mandatory treatment, as it can metastasize and spread throughout the body.
Dark spots or lines on the nails may occur due to hemorrhage. These are small blood clots that typically run vertically under the nails. This problem is not specific to any particular condition, but it may be associated with acute systemic lupus erythematosus, nail psoriasis, and antiphospholipid syndrome (thick blood).
Symptoms of endocarditis (inflammation of the heart) may develop slowly or suddenly. Some of them include fever, chills and sweating. Other symptoms:
When the cause of dark spots or lines in the nails is hemorrhage associated with endocarditis, intravenous injections of antibiotics may be needed. It is necessary to diagnose the condition as soon as possible so that the correct treatment option can be applied.
Also, a change in pigmentation in the nail in the form of a line can be the cause of subungual melanoma (see the previous section of the article on skin cancer).
Vitamin B12 deficiency, or folate deficiency anemia, can cause a wide range of symptoms. They develop gradually, but can get worse if the condition goes untreated for a long time. Overall, adequate nutrition is important to maintain healthy fingers and toes. Changes in the appearance of the nail may be the first sign of vitamin B12 deficiency.
The main symptoms of this condition may include fragility, discoloration, or lines. You should see a doctor as soon as possible to prevent any complications.
With some systemic diseases (diabetes, folate deficiency anemia, liver cirrhosis, renal failure, etc.), the nails become white, and some areas that have not lightened may appear as dark spots
Most people with type 2 diabetes often experience leg problems. This is caused by poor circulation and nerve damage. Typically, this condition causes hardening and darkening of the toenails.
Lichen planus is a skin rash caused by a disorder of the immune system. This condition may appear as colored lines with rashes, itching and painful lesions that develop and spread throughout the body.
Subungual hematoma is the most likely cause of black spots under the nails. It can also be found under your toenails.
Nail injuries can be especially painful. This can also cause the nail plate to change color from red to blue and finally black once the blood has dried.
Subungual hematoma is very common and can be caused by any of the following:
The color and appearance of a nail can say a lot about your overall health. If a person is unable to determine the actual cause of the small black spots on the nails, it is necessary for a doctor to examine the condition and determine the actual cause of the problem.
Small black spots may be a sign of the following conditions:
Treatment for nails will depend on what is the underlying cause of the condition. Black nails can be painful, but with simple home remedies the discomfort can be reduced. You can try the following to get rid of dots and blemishes on your nails:
You should avoid using someone else's nail polish, as well as scissors and clippers, as this can be a major cause of infection. You need to use individual tools for pedicure and manicure when visiting beauty salons. You should avoid deep cuticle removal as this can cause infection.
You should avoid the urge to bite your nails and always try to keep them clean and dry. For healthy nails, you need a diet rich in vitamins and proteins. Vitamin B and calcium, found in eggs, meat, whole grains and milk, are helpful for growing strong nails.
If you have ingrown toenails, do not hesitate to consult a doctor. If you frequently use your hands and nails at work, you should wear rubber gloves to protect them.
Acetic acid can help control the problem of dark toenails. You need to mix a little vinegar with water and soak your feet in this solution. After that, dry them and wipe with a towel. Repeat these steps two or three times to get rid of the problem.
Baking soda is an effective remedy for dark spots on nails and is also an antifungal agent. You need to add a little baking soda to a small amount of water to get a solution. After a bath of vinegar solution, you should soak your feet in a soda solution.
The antimicrobial properties of tea tree oil make it an ideal home remedy for getting rid of dark spots on your nails. It is known as a miracle cure for skin and hair problems. Place three to four drops of tea tree oil in a container, add enough water, then soak your feet in the liquid for about 20 minutes.
This is another effective home remedy that can be used to get rid of nail problems as well as the pain associated with them. Mix about a quarter cup of salt with ten cups of warm water. Keep your feet in the solution for about fifteen to twenty minutes. If you perform the procedure regularly, you can easily get rid of dark spots on your toenails and painful sensations caused by local causes.
Internal diseases are determined by nails
Everyone would like to have a perfect manicure and pedicure all the time, but sometimes problems arise with this. Internal diseases can be identified by external changes. Nails can also be an indicator. If you have any health problems, spots may appear on your fingernails and toenails. As soon as you notice this, consult a doctor as soon as possible. Remember that if the body is healthy, then stains will never appear on the plates.
The status of a person can be determined by the well-groomed hands, so if you often meet with influential people, try to notice changes in your appearance.
The color of the spots has its meaning
You need to remember that getting rid of the stain will not solve the problem. It lies inside your body, and the cause needs to be treated. And all external manifestations mean that you need to change something in your lifestyle, and then you will get results. That is, spots on the nails that are more or less dark should become an alarm bell, after which you need to find out and eliminate the cause of their appearance.
Let's look at each type of fingernail and toenail stains separately. This will help you navigate the path to treatment.
When wearing uncomfortable shoes, a dark spot may appear on the big toe nail. In this case, you need to be careful with this and it is better to change your shoes so as not to further injure the nail tissue, because this can lead to more complex and serious consequences, and slightly dark spots on the nails will turn into your permanent problem.
If you have dark spots on your toenails, this may be the beginning of the development of fungus. Contact a doctor who can make an accurate diagnosis. In cases where the stains on the nails are quite dark, this can lead to peeling of the nail, which in itself is not very good or pleasant.
Some polishes can cause spots on your nails. If you notice this, it is better to throw it away.
You can see what all the examples look like in the photo. You can also read what signs there are about this.
Stains on nails can be removed
If they appear, you need to go to the dermatovenereal department of the hospital and consult a doctor.
The easiest way to remove stains is on nails that have dark shades. It is easy to determine the cause of their appearance. And in the salon everything will be cleaned quickly and efficiently, but only after the cause has been eliminated.
At the same time, if the spots on the nails are not very dark, this means that the disease is progressing and has not yet reached its peak. It is at this moment that you need to start treatment so as not to miss the moment.
Remember that in order to always look and be healthy, you need to pay attention to detail. It’s not without reason that they say that the devil is in the details. And to prevent it from reaching your health, you will have to pay attention to the slightest changes.
Some of the above problems can be solved at home. To do this, you need to slightly file the surface of the nail with a highly abrasive file, and then apply a healing agent to the surface of the finger. In such cases, it is recommended to use olive oil with the addition of a vitamin complex, a decoction of parsley with sea salt, a decoction of oak bark and chamomile. All these components have a good effect on the condition of your hands and feet.
If you have already been to the doctor, then you can apply the medicine prescribed by him in the same way. It is also useful to make various types of baths.
Almost everyone faces the problem of darkening on the plate, but for some it goes away on its own, while others have to put in a lot of effort to correct the situation. Therefore, if you are faced with this kind of problem, then do not be upset, but simply do not delay treatment. Then very soon everything will pass, and you will forget about it like a bad dream.
A dark spot on the nail is a fairly common phenomenon that almost anyone can encounter in their life. However, there is no single reason that could explain its appearance, since spots under the nails can occur in absolutely healthy people and in those who suffer from some kind of illness. There is a widespread belief that such dark spots are exclusively manifestations of a fungal infection. But such judgments are erroneous.
Sometimes the cause of the appearance of black stripes under the nails can be a hereditary factor. In such cases, you can seek advice from specialists who will offer effective ways to eliminate them. However, the vast majority of black spots on nails are the result of the action of pathogenic microorganisms on the tissue. These include, for example, fungi and bacteria. Other factors that worsen the condition of the nails, causing dark streaks to appear on them, include:
It is important to note that dark streaks under the nails are normal for people of some races. Examples include Africans, Asians or Indians. These stripes on the nails are called Hutchinson's signs - they do not pose any threat to human health and life.
The most common reason why black stripes appear on the nails as a result of external influences is considered to be trauma. This could be a bruise, an accidental or intentional blow. As a result, a hematoma or bruise forms under the nail - blood accumulated after damage to the capillaries. Since bruises on the feet are more common, spots under the nails on the toes appear more often than on the hands. This is how a red spot appears under the big toe nail.
Over time, the color changes and acquires a burgundy hue. Over time, the bruise begins to take on the appearance of a blue spot on the nail, after which it turns black. When palpating the injured area, pain is often felt. Gradually, the hematoma resolves or goes away as a new nail grows. Often, dark dots will remind you of a nail plate injury for some period of time. It is noteworthy that a person often forgets when exactly he received an injury that caused a similar hematoma on his big toe.
Another reason for the appearance of black stripes under the nails is the use of aggressive black varnishes. Covering the nail plate with such low-quality products, especially without a protective base, can leave black spots that even a good nail polish remover cannot remove. They often disappear naturally after the nail grows out.
Sometimes brown spots on nails appear after exposure to sunlight or certain chemicals, or prolonged exposure to water. This phenomenon is quite rare. It can be compared to the appearance of freckles, which occur when exposed to seasonal or other irritants.
You need to understand that spots on the toenails or fingernails may indicate some kind of pathology in the body. It is important to determine its cause. After all, getting rid of the stain will not solve the problem. Therefore, the sudden appearance of spots of any color on the nails of the toes or fingers should alert you: you need to quickly find out their nature and begin treating the root cause.
With vitamin deficiency, the stripes or spots are usually dark in color, and with pathology of the kidneys or stomach - white. With problem skin, the lines on the nails are yellow. To get rid of them, you need to remove the cause, that is, treat the skin. To do this, you need to figure out whether everything is in order with your health, since skin problems can also signal the presence of some kind of internal problem. In addition, yellow spots can often be a manifestation of a fungal infection.
A blue spot on the thumb, as already mentioned, can occur after a bruise. This is a blood clot that forms at the site of injury. In such situations, you should make sure that the fingers are intact and there are no fractures. After some time, the nail will grow back and the damaged area will disappear. However, if new blue spots appear on your finger, you should definitely consult a doctor.
A black line under the nail may indicate liver disease, and a brown spot may indicate that the body does not have enough folic acid or protein. The problem can be resolved by revising your diet. If reddish spots appear on the nails, it can be assumed that they are caused by injury, psoriasis or heart disease.
What methods can be used to remove streaks on nails? This question is asked not only by women, but also by men who are faced with this problem. It can only be resolved by a specialist who, after a visual examination, prescribes tests to clarify the diagnosis and determine the cause of the disease.
In addition to the medications that the doctor prescribes to eliminate the cause of the disease, the patient is usually prescribed a complex of vitamins and minerals to strengthen the body. They will significantly improve the condition of the nail plates. Often, effective folk methods are used in combination with traditional therapy, which should be used only on the recommendation of the attending physician.
Dark spots on toenails are one of the fairly common phenomena that many have encountered. Often such a finding is accidental, however, there are situations when visual changes in the nail plate are accompanied by a number of additional symptoms (pain, itching, splitting of the nail, etc.).
Nails are a kind of mirror of the human body. They are often the first to change in the presence of some disease or under the influence of external factors. That is why, if a dark spot or any other color appears under the nail of the big toe, it is worth paying due attention to this problem and contacting a specialist.
The dark spot under the toenail can have different color characteristics. Depending on the main reason that caused this problem, the following are the most common variants of darkening of the nail plate:
In addition to such a formidable disease, dark spots also occur against the background of a deficiency of vitamins and minerals. In any case, if dark spots appear on the toenails, it is necessary to carry out differential diagnosis to establish the root cause of this condition and select the appropriate treatment method.
One of the fairly common causes of the corresponding symptom is wearing uncomfortable and tight shoes. This is especially true for diabetics and people with vascular pathology of the lower extremities. Constant microtrauma causes damage to the skin and nail plates on the toes.
Infection with a fungus of the genus Aspergillus causes dark spots under the toenails. The patient's photo below demonstrates this pathology.
In addition to the visual defect, the patient is bothered by itching and general discomfort over the entire surface of the foot. Such damage to the nail plates requires appropriate comprehensive antifungal treatment using adequate doses of drugs.
The following patient developed a dark spot on his toenail as a result of a traumatic injury. The photo shows a visual picture of a subungual hematoma.
Additional symptoms are pain and a feeling of fullness in the affected area. In this case, nail trephination remains a very common and effective treatment method. It involves removing a fragment of the damaged plate with drainage of remaining blood. This reduces pain and shortens the recovery period of the nail.
One way or another, if dark spots appear on your nails, you should definitely consult a specialist. He will be able to carry out appropriate diagnostic measures to determine the cause of the pathology and offer adequate options for solving the problem. Self-medication and wait-and-see tactics can sometimes cause a significant deterioration of the situation with the development of a number of complications.
Problems with nails arise for various reasons, but experienced mycologists are able to diagnose internal diseases of the body based on external changes alone. That is, nails, like the tongue, are a barometer of a person’s internal state. What do the black dots under the nails tell you? What provokes their appearance? What reasons? What to do in such cases? Let's figure it out together
Here are the most common causes of black spots under the nails:
As you can see, fingernails and toenails turn black for various reasons. And these reasons influence the nature, size and shape of the spots.
Black dots on nails come in different sizes and shapes. Most often they look like this:
Shapeless black spots or darkening of the surface of the nail. This is a clear sign of nail fungus.
Small, dark, round dots are in most cases simple hematomas. These are the consequences of blows, bruises with blood leaking under the nail. This often occurs in athletes and skiers on their toenails. Sometimes people simply don’t notice such small spots. As a rule, this problem does not require treatment, since it is considered a cosmetic defect and goes away as the nail grows.
Small black dots that are located randomly along the nail plate may indicate a contaminated liver. If you are sure that it is not a fungus, then such stains should not be ignored. Have you found spots of this nature? Then it is recommended to watch them for a while. Are they changing? Hematomas usually disappear after a few weeks. When dots or spots change their character towards increasing the area, changing the shape of the nail plate, then this is a signal for action. Be sure to visit a dermatologist or mycologist. Don't start the problem!
What to do to prevent the problem from occurring? It is easier to prevent any disease than to treat it. Same with nail diseases
It is easier to prevent any disease than to treat it. Same with nail diseases. If you follow certain preventive measures, your nails will not cause trouble or problems. And in this matter, a lot depends on your lifestyle and occupation.
If you play sports professionally, then it is unlikely that you will avoid at least occasionally the appearance of injuries, bruises, and bruises on your nails. Most often, runners, skiers, and football players are susceptible to such problems. By the way, you need to take into account that an ordinary locker room with changing shoes and poor hygiene can also put you at risk of becoming infected with a fungus.
When you walk and travel a lot, then this risk also exists in hotels and hosting services. In this case, the source of fungal infection can be a hotel shower stall or carpet.
Work in production is fraught with injuries no less often than with fungal infection. Therefore, take care of individual comfortable shoes and gloves.
Remember to wear comfortable shoes when traveling to protect your nails from rubbing and sweating.
Women need to be especially careful when working with chemicals at home. This refers to cleaning products for bathtubs, toilets, and stoves. They contain too aggressive substances that have a bad effect on your nails and destroy them. Always protect your hands with gloves!
An important condition for maintaining nail hygiene is an individual set of manicure tools, which you should never lend to anyone. In this way, you will protect yourself from infection not only with fungus, but also with other diseases.
Constant nail injuries are another reason to protect and care for them. And even if they happen rarely, then you shouldn’t start the problem, let it take its course. Sometimes a small blackhead can turn into a big hassle.
Particular attention should be paid to nutrition. After all, infection with a fungus occurs against the background of weakened immunity. More often this happens when a woman follows diets that are specific to food taboos. A sufficient amount of vitamins A and E in the body, which are considered beauty vitamins, will serve as additional protection for your nails.
As for the cosmetic camouflage of nail defects, if it is not a fungus, but really an injury, then you can cover the nail with biogel.
Under it, the nail plate has the ability to “breathe”. It is not recommended to cover an injured nail with ordinary varnish. You will hide the problem, but this will not contribute to the health of the nail.
So, if black dots or spots appear under your nails, you should definitely see a doctor. Do not refuse the prescribed examination. Perhaps you really have problems with your liver or oncology and the first alarm bells about this are your nails.