Finding black spots under your toenails can be scary, but most of the time, they’re harmless. Still, it’s worth understanding what they could mean, what the symptoms are, and when you should see a doctor to have them checked out.
It’s important to learn about these spots because catching a problem early can make a big difference. However, trying to figure out what’s going on by yourself isn’t a good idea. Self-diagnosis can lead you down the wrong path.
In this article, we’ll explore some potential causes for black spots under toenails, discuss how to identify them, and tell you when it’s time to get professional medical advice.
What causes black spots under toenails?
Black spots under your toenails are often caused by injuries, but they can sometimes be caused by other things. It’s important to know what’s going on so you can take care of your feet and keep them healthy.
Trauma and injury
One common cause of black spots is trauma to the toenail. This includes:
- Subungual hematoma. If you stub your toe, drop something heavy on your foot, or wear shoes that put pressure on your toes, blood can get trapped under the nail. This is called a subungual hematoma. At first, it may look red or purple, but over time, it can turn dark brown or black. You may feel pain or pressure under the nail.
- Shoe pressure. Shoes that are too tight can also cause trauma to the nail bed.
Fungal infections (onychomycosis)
Fungal infections are less likely to cause black spots directly, but they can weaken the nail and make it easier to get injured or discolored. Fungal infections usually cause the nail to turn yellow, thicken, and become brittle. Fungal infections usually cause the nail to turn yellow, thicken, and become brittle; however, other colors can appear as well.
Less common, but serious, causes
While toenail trauma and fungal infections are the most common culprits, those black spots under your toenails could signal something more serious.
Melanonychia
Melanonychia is the darkening of the nail, often showing up as a brown or black band. It happens when the cells in your nail start making more melanin, which is the pigment that gives skin its color.
There are a couple of types:
- Longitudinal melanonychia: This is a band that runs from the base of your nail (cuticle) to the tip. It’s pretty common in people with darker skin tones and is often just a normal variation. But it can also be triggered by injuries, medications, or even other health problems.
- Transverse melanonychia: This shows up as a horizontal band across the nail. It’s often linked to a systemic illness or medication.
Subungual melanoma
Subungual melanoma is a rare, but very serious, type of skin cancer that develops under the nail. It’s important to figure out whether the spot is melanoma or something else.
Here are some key things to watch out for:
- Hutchinson’s sign: This is when the pigment from the spot starts to spread onto the skin around the nail (the nail fold).
- Rapid growth or change: If the spot is growing quickly or changing its appearance, that’s a red flag.
- Nail dystrophy: This means the nail is becoming distorted or damaged.
- Bleeding or ulceration: Any bleeding or open sores around the nail need to be checked out.
Some things can make you more likely to get subungual melanoma:
- Family history: If you have relatives who’ve had melanoma, your risk is higher.
- Prior trauma: If you’ve injured your nail in the past, that could increase your risk.
Other potential causes of black spots under toenails
While trauma is the most common reason for black spots under your toenails, other things can cause it too. Here are a few other possibilities:
- Medications: Certain drugs can cause discoloration of the nails as a side effect. Chemotherapy drugs are a well-known culprit, but some antibiotics may cause it, too.
- Systemic diseases: Sometimes, a systemic disease, including autoimmune diseases, can show up in your nails. Addison’s disease and Laugier-Hunziker syndrome are two examples.
- Nutritional deficiencies: While it’s less common, a severe nutritional deficiency can affect the look and health of your nails.
If you’re concerned about the spots on your toenails, it’s always best to see a doctor to rule out anything serious.
Diagnosis and when to seek medical attention
If you have a black spot under your toenail, you should see a dermatologist or podiatrist to get it checked out. They’ll visually examine your nail and ask about your medical history to try to figure out what’s going on.
To get a clearer picture, they might also perform some diagnostic tests, such as:
- Nail biopsy: This involves taking a tissue sample from under the nail to look for melanoma or other problems, potentially requiring a nail biopsy.
- Fungal culture: This test rules out a fungal infection.
- Dermoscopy: This involves using a special magnifying tool to get a closer look at the nail.
Get medical help right away if you notice any of the following:
- A dark spot that’s growing or changing quickly
- Pain or swelling around the nail
- Hutchinson’s sign (when the pigment from the spot spreads to the skin around the nail)
- Nail dystrophy or bleeding
- You’re just generally unsure about what’s causing the spot
Frequently Asked Questions
What does early stage nail fungus look like?
Early-stage nail fungus often presents as a small white or yellowish spot under the toenail. The nail may also thicken slightly or become brittle. It’s usually painless at this stage, which is why it can easily be overlooked.
How can you tell the difference between nail fungus and melanoma?
Distinguishing between nail fungus and melanoma can be tricky, as both can cause discoloration. However, melanoma often appears as a dark streak extending from the nail base (cuticle) up the nail. Nail fungus tends to cause more widespread discoloration and thickening. If you’re concerned, see a doctor for a proper diagnosis.
What does stage 1 nail melanoma look like?
Stage 1 nail melanoma might appear as a dark band or spot on the nail that’s wider than 3mm. There might also be changes in the nail’s shape or texture. Bleeding or ulceration around the nail is also possible. Early detection is key, so any suspicious nail changes should be checked by a dermatologist.
What is the black mold under my toenail?
While it’s possible the discoloration under your toenail could be related to a type of mold, it’s more likely due to other causes like nail fungus, a bruise (hematoma), or, in rare cases, melanoma. Black discoloration warrants a professional evaluation to determine the underlying cause.
What can be mistaken for toenail fungus?
Several conditions can mimic toenail fungus, including nail psoriasis, trauma to the nail (leading to bruising), bacterial infections, and even certain systemic diseases. It’s important to get a definitive diagnosis from a doctor to rule out other potential causes and receive appropriate treatment.
Closing Thoughts
Black spots under your toenails can be caused by many things, from a simple bruise to something serious like melanoma. It’s important to keep an eye on any changes to your nails and to catch any problems early.
Most of the time, a dark spot under your nail isn’t something to worry about. But it’s important to get it checked out by a doctor to make sure you get the right diagnosis and treatment. If you’re concerned about any changes to your nails, talk to your doctor.