Expert Foot & Ankle Treatment from Michigan’s #1 Podiatrist - Balance Foot & Ankle Specialist
Noticing Dark Lines or Streaks in Your Nails?
Black Streaks in Nails: What They Mean and When to Worry
Black streaks in nails can be harmless or a sign of something more serious. While some causes, like trauma or fungal infections, are minor and treatable, others—such as melanoma—require urgent medical attention. In this guide, we’ll break down the possible causes, what symptoms to watch for, and when to see a medical specialist like a podiatrist or dermatologist.
Understanding Black Streaks in Nails: Causes and Risks
Black or dark brown vertical streaks in nails—called melanonychia—can result from trauma, infections, vitamin deficiencies, or even systemic diseases. In some cases, especially if only one nail is affected or the streak widens over time, it may be a sign of subungual melanoma, a rare but serious form of skin cancer. Differentiating between harmless and dangerous types is key to getting the right treatment. Always seek medical advice if you’re unsure.
Black Streaks Under the Nails Causes, Symptoms & Best Treatment!
Black Streaks under the nails (fingernails or the toenails) can be very dangerous. Make 100% sure that you don’t have something more dangerous!
Look:
- Red & black toenail pain can be improved with a few simple treatment changes.
- We are foot doctors & we see this problem get better almost every day.
- The goal is to solve this problem without medication or surgery if at all possible.
So, let’s GO!
Toenail Pain (Toenail Fungus, Ingrown Toenails, Discolored Toenails)
Worried About a Dark Streak in Your Nail? Get Expert Advice Today
Don’t guess when it comes to your health. If you’ve noticed a black streak in one or more of your nails, schedule a visit with Balance Foot & Ankle. Our board-certified podiatrists will perform a thorough evaluation to identify the cause and provide the right treatment or referral.
Call now or book an appointment online—your peace of mind starts here.
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10 Causes of Black Streaks in Nails
Are you noticing black streaks in nails or a black streak on a nail that wasn’t there before? Don’t panic—but don’t ignore it either. These dark lines can be harmless or a sign of something more serious. Let’s break down 10 common causes of black streaks on nails and help you decide whether it’s time to see a podiatrist or dermatologist.
1. Nail Trauma
A common cause of a black streak in nail is minor trauma—think stubbing your toe or banging your hand. This results in bleeding beneath the nail (subungual hematoma), creating a dark line that may grow out over time.
2. Subungual Melanoma (Skin Cancer)
One of the most serious—but rare—causes of black streaks in nails is subungual melanoma. If you notice a black streak on a single nail, especially one that widens or darkens, seek medical attention immediately. Early detection is key to survival.
3. Fungal Infection
Certain fungal infections, particularly in toenails, can cause black streaks on nails. These infections often accompany other symptoms like nail thickening, discoloration, or foul odor.
4. Vitamin Deficiencies
Deficiencies in nutrients like Vitamin B12 or iron can cause pigmentation changes or lines under your nails. A blood test can help determine if this is the culprit behind your black streaks.
5. Medication Side Effects
Some medications—including chemotherapy drugs and antimalarials—may cause dark streaks to appear in nails. If you’ve recently started a new medication and notice nail changes, consult your doctor.
6. Melanonychia
Melanonychia is the medical term for pigmentation that appears as black streaks in nails. It’s more common in people with darker skin and may affect multiple nails. While usually benign, it still warrants evaluation.
7. Psoriasis or Eczema
These chronic skin conditions can also affect the nails, leading to discoloration, pitting, or dark streaks. Nail psoriasis is sometimes mistaken for fungal infections or trauma.
8. Lichen Planus
This inflammatory condition can affect the skin and nails. In the nails, it may cause longitudinal dark streaks, thinning, or even nail loss over time.
9. Hormonal Changes
Hormonal shifts—especially during pregnancy or due to thyroid issues—can sometimes lead to changes in nail appearance, including streaking or pigmentation.
10. Benign Moles or Pigment Cells
Sometimes, a black streak in a nail may simply be the result of a mole or benign melanocytic activation under the nail. These are usually harmless but should be tracked for changes.
Red or Black Toenail Picture & Photo Gallery:
Look:
- A red toenail generally means fresh blood or a fresh injury.
- This can be called a toenail hematoma or fresh blood from repetitive irritation.
- A black toenail is generally more dried blood that has crested underneath the toenail.
- Very infrequently, can a black toenail be something more dangerous like melanoma?
- It is also possible for your toenail to the infected with toenail fungus. This can also then result in rubbing and bleeding after the toenail fungus.
- If there is toenail fungus, this is usually more of a brown or yellow color.
- A toenail falling off is a widespread problem as well.
Please click on the photo gallery for descriptions & full-size photos!
Black Streaks Under The Nails Overview
Black Streaks under the nails (fingernails or the toenails) can be very dangerous. Follow our diagnosis guide to see if you should be worried!
Note: None of the photo galleries shows any true melanoma or cancerous growth. This is because it is that rare that we don’t actually have any photos of it!
Causes:
- The most common cause of black under the toenails is dry blood.
- Most People Should Not Be Worried!
- A thick black dark streak could be a subungual melanoma- a type of skin cancer.
- Don’t be too worried, though. The odds are low that you actually have this tough but better safe than sorry!
- Watch the video above to get a better idea if this is what you have.
- But always make sure to get checked out.
Dangerous Cause:
- Subungual melanoma is the most dangerous cause.
- It is a rare form of skin cancer; it is usually seen between ages forty and seventy.
- It is not due to sun exposure or trauma.
- It just appears one day without any incident.
- If your dark spot appears after an injury, then you are most likely on the safe side.
Subungual Melanoma:
- The outlook is usually excellent if the cancer is confined to just the toe.
- Most people that suffer from this disease have avoided seeking treatment for many, many years. It has usually spread far throughout the body.
- If you are cautious and follow up on the streaking and ulcerating in a reasonable amount of time, you will most likely be safe.
- The cure consists of excising the lesion or amputating the tip of your fingernail.
- See your podiatrist as soon as possible!
Visit a podiatrist for a biopsy immediately if:
- The black streak is over 3 millimeters in width.
- The streak is widest at the start of the nail origin.
- The streak is not uniform or appears disrupted.
- The streak changes color the further you get.
- The streak continues from under the nail into the skin, termed “Hutchinson’s sign.”
- The nail becomes deformed, bloody, or starts to crack in the area of the streak.
- The nail looks very unusual compared to the other nails.
- The streak is more common in the thumb and the big toe.
- In this case, the streak may even be white; in this case, be aware of a nodule or irregularity forming under the nail plate.
- If you have ever considered that there may be a wart underneath your nail that is just not healing.
Safe Causes:
- The odds of the streak in your fingernail are actually pretty low because many people, especially African Americans, normally have light, thin streaks of dark pigment that form a vertical line down their nail, which is completely normal. It is effortless to predict whether the streak is dangerous or safe.
- Normal vertical streaks of pigment that are not melanoma. This is especially common in non-white individuals. These are usually thin lines in a very normal-looking nail; check the guide below to see if you are on the safe side or if you should get it checked out.
- Trauma and loss of fingernail leading to a streak of blood. If the blood is not advancing, then you should get it checked out to be safe! But this should eventually grow out at 1mm per month.
Probably safe if:
- The streak is less than 3 millimeters in width.
- The streak is uniform in length and of continuous color as it progresses down the nail.
- The streak or pigment is only present in the nail and not in the skin.
- The nail is not deformed, bloody, or cracked in that area.
- The nail looks normal compared to the other nails.
Other Causes Of Black Spots Under The Toenail:
- Blood under the toenail. Other causes include:
- Pseudomonas nail infections
Toenail Fungus Can Cause Black Streaks:
If the above does not sound like your situation, consider toenail fungus as well.
- Toenail fungus is associated with 80% of all toenail problems.
- It usually manifests as thick yellow toenails, but there can be brown and black marks as well.
Toenail Fungus Is Associated With 80%+ Of All Toenail Problems:
Symptoms of Toenail Fungus:
- Thick yellow toenails.
- Crumbling debris underneath the toenails.
- Incurvated or possibly ingrown toenails.
- Discoloration or streaking.
Click on this link to our comprehensive nail fungus home treatment guide. Always be sure to see a podiatrist if you are ever unsure!
Home Treatment:
How to fix toenail fungus:
- There are many different types of toenail damage.
- In our experience, about 90% or more is related to toenail fungus.
- The key to toenail fungus is to trim it as much as possible and file that nailed down.
- If you can do that, you have to make sure you can kill fungus the rest of the way.
- The best way to do that is to soak exfoliate the affected toenail skin. So, consider foot soaks.
- At the same time, you have to apply antifungal medication such as these medications recommended here or the toenail repair pens.
Best Toenail Repair Products:
Best Toenail Repair Pen.
Top Choice For Direct Toenail Application.
Top Choice For Cream For Toenails & Webspaces.
Great Option For Foot Soak.
Great Tea Tree Oil Treatment
Price:
$14.44
$20.88
Price not available
$17.97
Price not available
Overview:
4 Pens with quick dry application that leaves a sealing lid on top. Easy to store and apply. Key is still to trim/file the toenail first!
All natural option that is toxic to fungus. This is similar to tea tree oil in that respect but can be more effective. You still need to exfoliate dead skin and trim thick toenails.
All natural cream option. This is a good option compared to some of the quick dry gels. This can be used on the skin surrounding your toenails.
Safe, cost effective and relaxing all at the same time! This needs to be used in a 20 minute foot soak. Works well for exfoliating loose skin/toenail as well as softening.
Tea Tree Oil is well studied and an all natural anti-fungal treatment.
Pros:
Easy to use, quick drying. This fills into the cracks and seals them with minimal mess. This is great for sealing even dehydrated keratin granulations.
All natural, relatively cost effective. 1,000s of reviews with excellent results. Very clean and quick drying, easy to apply.
Relatively cost effective. All natural tea tree oil that is proven toxic to fungus. Can be used on surrounding skin as well.
Very safe, little risk, low cost and very effective if used correctly. The key is to use it as an aid to soften and exfoliate loose/dry dead skin and toenail.
Great reviews at 4.7/5 at 500+ overall reviews. Well proven and natural option.
Cons:
0% chance of working if your toenail is loose and has no blood supply. Make sure you trim and file any loose finger or toenail. Otherwise “0% CHANCE OF WORKING!” You cannot restore a dead toenail without blood flow.
Small amount and a little more expensive than some other options. Once more has 0% chance of working if your goal is to heal a dead, detached toenail or dry skin. Are you noticing this is a trend? This is really the key!
Still more expensive than other options. Can get messy all over different areas of your foot. Key is still debride and cleaning your dry dead toenails and skin. TRIM them!
It once more has 0% chance working if you are trying to save loose and dead crusty skin. Fungus will always grow on this if no blood flow. It can not regenerate dead skin, only exfoliate it.
Not the greatest amount of solution, the all natural solutions can be more expensive.
Crucial Tips:
There is some evidence that these active ingredients work, just be aware: These are not FDA approved and massively studied medications!
There is some evidence that these active ingredients work, just be aware: These are not FDA approved and massively studied medications!
There is some evidence that these active ingredients work, just be aware: These are not FDA approved and massively studied medications!
There is some evidence that these active ingredients work, just be aware: These are not FDA approved and massively studied medications!
Although tea tree oil does nave studies and is antifungal, it is not an FDA approved medication and not studied for this specific use.
Affiliate Link (Buying through these links will connect you to Amazon):
Best Toenail Repair Products:
Best Toenail Repair Pen.
Price:
$14.44
Overview:
4 Pens with quick dry application that leaves a sealing lid on top. Easy to store and apply. Key is still to trim/file the toenail first!
Pros:
Easy to use, quick drying. This fills into the cracks and seals them with minimal mess. This is great for sealing even dehydrated keratin granulations.
Cons:
0% chance of working if your toenail is loose and has no blood supply. Make sure you trim and file any loose finger or toenail. Otherwise “0% CHANCE OF WORKING!” You cannot restore a dead toenail without blood flow.
Crucial Tips:
There is some evidence that these active ingredients work, just be aware: These are not FDA approved and massively studied medications!
Affiliate Link (Buying through these links will connect you to Amazon):
Best Toenail Repair Products:
Top Choice For Direct Toenail Application.
Price:
$20.88
Overview:
All natural option that is toxic to fungus. This is similar to tea tree oil in that respect but can be more effective. You still need to exfoliate dead skin and trim thick toenails.
Pros:
All natural, relatively cost effective. 1,000s of reviews with excellent results. Very clean and quick drying, easy to apply.
Cons:
Small amount and a little more expensive than some other options. Once more has 0% chance of working if your goal is to heal a dead, detached toenail or dry skin. Are you noticing this is a trend? This is really the key!
Crucial Tips:
There is some evidence that these active ingredients work, just be aware: These are not FDA approved and massively studied medications!
Affiliate Link (Buying through these links will connect you to Amazon):
Best Toenail Repair Products:
Top Choice For Cream For Toenails & Webspaces.
Price:
Price not available
Overview:
All natural cream option. This is a good option compared to some of the quick dry gels. This can be used on the skin surrounding your toenails.
Pros:
Relatively cost effective. All natural tea tree oil that is proven toxic to fungus. Can be used on surrounding skin as well.
Cons:
Still more expensive than other options. Can get messy all over different areas of your foot. Key is still debride and cleaning your dry dead toenails and skin. TRIM them!
Crucial Tips:
There is some evidence that these active ingredients work, just be aware: These are not FDA approved and massively studied medications!
Affiliate Link (Buying through these links will connect you to Amazon):
Best Toenail Repair Products:
Great Option For Foot Soak.
Price:
$17.97
Overview:
Safe, cost effective and relaxing all at the same time! This needs to be used in a 20 minute foot soak. Works well for exfoliating loose skin/toenail as well as softening.
Pros:
Very safe, little risk, low cost and very effective if used correctly. The key is to use it as an aid to soften and exfoliate loose/dry dead skin and toenail.
Cons:
It once more has 0% chance working if you are trying to save loose and dead crusty skin. Fungus will always grow on this if no blood flow. It can not regenerate dead skin, only exfoliate it.
Crucial Tips:
There is some evidence that these active ingredients work, just be aware: These are not FDA approved and massively studied medications!
Affiliate Link (Buying through these links will connect you to Amazon):
Best Toenail Repair Products:
Great Tea Tree Oil Treatment
Price:
Price not available
Overview:
Tea Tree Oil is well studied and an all natural anti-fungal treatment.
Pros:
Great reviews at 4.7/5 at 500+ overall reviews. Well proven and natural option.
Cons:
Not the greatest amount of solution, the all natural solutions can be more expensive.
Crucial Tips:
Although tea tree oil does nave studies and is antifungal, it is not an FDA approved medication and not studied for this specific use.
Affiliate Link (Buying through these links will connect you to Amazon):
Recommended foot fungus products:
- It is also essential to fix your foot fungus.
- Even if you cure your toenail fungus, keep your toenails trimmed in healthy: your foot fungus can spread back into toenails.
- So make sure you treat your foot fungus, as well as your toenail fungus.
Best Foot Fungus Products
Best Foot Powder Option For Shoes.
Best Shower Body Wash
Best choice for Foot Bath Mix
Best & Most Cost Effective Foot Soak Tub.
Price:
$26.31
$17.85
$16.93
$18.97
Overview:
3 pack of foot powder spray. This is great for shoes and feet, but not as practical outside the foot or shoe.
Great cost effective shower wash.
Mix of epsom salts, tea tree oil for a good price.
This is a cost effective tub for foot soaks. You still need to also buy a foot soak powder or solution!
Pros:
If you sweat in your shoes, this is your best bet. This will soak up sweat and kill fungus. Very effective and excellent Amazon reviews. 3 pack online is the price of one bottle at the store.
Over 5,000 5 star amazon reviews. Great reviews, medically proven component in tea tree oil. All natural with excellent results.
Epsom salts and tea tree oil have proven effect. Epsom salts make your loose skin flake off and tea tree oil is anti-fungal. Great price and near 5 star review on Amazon.
Excellent choice for cost effective foot soak tub. Top notch reviews on amazon, great price.
Cons:
Powder makes a big mess. Good for shoes but it can get powder inside your shoes. Can have chemical like smell.
Can be more expensive than regular soap. It may not be enough by itself without soaking or especially further toenail treatment.
Foot soak by itself may not be enough to fix your problem, but a component. You also need a foot tub.
Not much downsides, it’s a tub! But you have to get foot soak powder or antifungal solution separately.
Affiliate Link (Buying through these links will connect you to Amazon):
Best Foot Fungus Products
Best Foot Powder Option For Shoes.
Price:
$26.31
Overview:
3 pack of foot powder spray. This is great for shoes and feet, but not as practical outside the foot or shoe.
Pros:
If you sweat in your shoes, this is your best bet. This will soak up sweat and kill fungus. Very effective and excellent Amazon reviews. 3 pack online is the price of one bottle at the store.
Cons:
Powder makes a big mess. Good for shoes but it can get powder inside your shoes. Can have chemical like smell.
Affiliate Link (Buying through these links will connect you to Amazon):
Best Foot Fungus Products
Best Shower Body Wash
Price:
$17.85
Overview:
Great cost effective shower wash.
Pros:
Over 5,000 5 star amazon reviews. Great reviews, medically proven component in tea tree oil. All natural with excellent results.
Cons:
Can be more expensive than regular soap. It may not be enough by itself without soaking or especially further toenail treatment.
Affiliate Link (Buying through these links will connect you to Amazon):
Best Foot Fungus Products
Best choice for Foot Bath Mix
Price:
$16.93
Overview:
Mix of epsom salts, tea tree oil for a good price.
Pros:
Epsom salts and tea tree oil have proven effect. Epsom salts make your loose skin flake off and tea tree oil is anti-fungal. Great price and near 5 star review on Amazon.
Cons:
Foot soak by itself may not be enough to fix your problem, but a component. You also need a foot tub.
Affiliate Link (Buying through these links will connect you to Amazon):
Best Foot Fungus Products
Best & Most Cost Effective Foot Soak Tub.
Price:
$18.97
Overview:
This is a cost effective tub for foot soaks. You still need to also buy a foot soak powder or solution!
Pros:
Excellent choice for cost effective foot soak tub. Top notch reviews on amazon, great price.
Cons:
Not much downsides, it’s a tub! But you have to get foot soak powder or antifungal solution separately.
Affiliate Link (Buying through these links will connect you to Amazon):
Best Toenail Fungus Clippers & Files:
- These are some great value heavy-duty clippers and sets. You have to be careful using at home, and deftly don’t use these if you have dangerous health conditions.
- The key is to cut straight across and file the nail down from the top to keep it from impinging in the corners.
- It is also important to make sure all dead, dry skin is removed surrounding the foot.
- This is where you should really see your podiatrist if you have any concerns or are worried about cutting or hurting yourself.
- This is something covered, so don’t take chances with your health!
Best Grooming Supplies
Best Value Clipping Set
Best Value Heavy Duty Clipper Set
Heavy Duty Non-Scissor Clipper
Price:
$9.99
$22.91
$9.99
Overview:
This is the Amazon best overall rated value set: Great Reviews and cost.
Value heavy duty clipper, nail file and currette for scooping under the nail.
Great alternative choice for heavy duty clipper if difficulty cutting with the other one.
Pros:
4.4/5 ratings at almost 800+ ratings. Multi-tool set that should be adequate for most people.
4.7/5 reviews with 200+ reviews. Strong clipper with files and currette, everything you need!
Excellent reviews, 4.8/5 with 600+ reviews. Some people prefer this grip
Cons:
It won’t work for heavy duty thickness. It can be dangerous clipping if you have health conditions.
It is still not perfect if you can’t reach your foot. See your podiatrist if health conditions.
No currette and no nail file, so you may need this.
Crucial Tips:
If your toenails are too thick and if you have dangerous health conditions, see your podiatrist for your toenail fungus!
If you have health conditions, be very safe at home, this can be a risky treatment! Be very safe.
Make sure to see your podiatrist if you have metabolic or blood flow conditions! Be safe if you can’t reach.
Affiliate Link (Buying through these links will connect you to Amazon):
Best Grooming Supplies
Best Value Clipping Set
Price:
$9.99
Overview:
This is the Amazon best overall rated value set: Great Reviews and cost.
Pros:
4.4/5 ratings at almost 800+ ratings. Multi-tool set that should be adequate for most people.
Cons:
It won’t work for heavy duty thickness. It can be dangerous clipping if you have health conditions.
Crucial Tips:
If your toenails are too thick and if you have dangerous health conditions, see your podiatrist for your toenail fungus!
Affiliate Link (Buying through these links will connect you to Amazon):
Best Grooming Supplies
Best Value Heavy Duty Clipper Set
Price:
$22.91
Overview:
Value heavy duty clipper, nail file and currette for scooping under the nail.
Pros:
4.7/5 reviews with 200+ reviews. Strong clipper with files and currette, everything you need!
Cons:
It is still not perfect if you can’t reach your foot. See your podiatrist if health conditions.
Crucial Tips:
If you have health conditions, be very safe at home, this can be a risky treatment! Be very safe.
Affiliate Link (Buying through these links will connect you to Amazon):
Best Grooming Supplies
Heavy Duty Non-Scissor Clipper
Price:
$9.99
Overview:
Great alternative choice for heavy duty clipper if difficulty cutting with the other one.
Pros:
Excellent reviews, 4.8/5 with 600+ reviews. Some people prefer this grip
Cons:
No currette and no nail file, so you may need this.
Crucial Tips:
Make sure to see your podiatrist if you have metabolic or blood flow conditions! Be safe if you can’t reach.
Affiliate Link (Buying through these links will connect you to Amazon):
Best Shoes For Toenail Injuries:
- The key to prevent toenail ripping and lifting is to have a good supportive pair of shoes.
- If you have a good supportive shoe that keeps pressure off your toes in your toenails, there will be no lifting and cracking to allow bacteria and fungus to get in.
- This almost seems counter-intuitive, but when people make a switch to perfect supportive shoes that fit properly, their toenail problems almost always get better over the next few months or a year.
- Your current nail is already likely destroyed, especially with joggers toe, but let the new nail growing healthy without new damage.
- Click the following link for our most recommended shoes. Try to focus on shoes with mesh and room around the big toe and also the smaller toes.
Good Luck with the Black Streaks Under the Nails!
Get The Best Shoe Fit:
- One of the most common biomechanical causes of toenail problems, bunions, hammertoes, and outside of the foot problems is poorly fitting shoes.
- A well-fitting and proper shoes can sometimes make all the difference in heel pain and overall foot pain.
- If you have too small or too big shoes, this can result in crowding or too much motion and sliding within your shoe.
- This can cause people to walk improperly and put more weight on their knees, hips, and lower back!
- We usually find that people make some of the 10 mistakes that we talk about.
- Watch the below treatment video to make sure that this never happens again!
Book Your Appointment Today—Relief Starts with One Call
Fast, Friendly, and Professional Treatment You Can Trust
Toenail Pain (Toenail Fungus, Ingrown Toenails, Discolored Toenails)
Frequently Asked Questions About Black Streaks in Nails
Common causes include trauma, fungal infections, vitamin deficiencies, or melanonychia due to pigmentation.
Not always. While some are harmless, sudden or changing streaks should be evaluated by a professional.
Yes. Subungual melanoma can appear as a dark vertical streak and may be life-threatening if not caught early.
It can be, especially in people with darker skin tones. However, any new changes should still be checked.
Signs of concern include streaks that grow, change color, or are accompanied by nail splitting or pain.
Either specialist can help. Start with a podiatrist if the streak is on toenails or with a dermatologist for fingernails.
In some cases, yes—especially B12 deficiency. However, testing is needed for confirmation.
If caused by a fungal infection, yes. Otherwise, most other causes are not contagious.
If caused by trauma, they often fade with nail growth. Persistent or spreading streaks should be evaluated.
