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Typically, toenails should be more or less a clear, partially translucent color. But sometimes, they can appear yellow, green, blue, purple, or black.

Several things can cause toenail discoloration (also known as chromonychia). These range from minor injuries to potentially serious health conditions.

Here’s a look at some of the most likely causes of your toenail discoloration and how they’re treated.

Nail fungus, also called onychomycosis, is one of the most prevalent causes of toenail discoloration. The most common organism to cause toenail fungus is called dermatophyte. However, mold or yeast can also infect toenails. Dermatophytes grow by eating your body’s keratin.

If you have nail fungus, your toenail color might be:

  • yellow
  • reddish brown
  • green
  • black

The discoloration tends to start under the tip of your nail. Left untreated, the discolored area will grow as the infection spreads.

Anyone can develop nail fungus. But certain people have a higher risk, including older adults and people with reduced blood circulation or weakened immune systems.

Other things that can contribute to nail fungus include:

  • frequent sweating
  • walking barefoot
  • small cuts or scraps near your nail

How to treat it

Mild fungal infections usually respond well to over-the-counter (OTC) antifungal treatments, which you can find on Amazon. Look for something that contains either clotrimazole or terbinafine. You can also try these 10 home remedies.

If you have a severe fungal infection that’s painful or causes your nail to thicken or crumble, it’s best to see a professional. Left untreated, several fungal infections can cause permanent nail damage.

You should also see a healthcare provider if you have diabetes and a fungal infection in your toenail.

If you’ve recently dropped something on your foot or stubbed your toe on something, your nail discoloration could be a symptom of a subungual hematoma. This injury can also result from wearing shoes that are too tight.

Subungual hematomas can make your nail appear red or purple. Eventually, this will change to a brown or black color. The affected nail will also likely feel sore and tender.

How to treat it

Subungual hematomas usually heal on their own within a few days. In the meantime, try to rest the affected foot. You can also wrap an ice pack in a towel and place it on the nail to help with the pain.

While the injury itself heals quickly it, it’ll take about six to nine months for the discolored nail to completely grow out.

If you notice that the pain and pressure isn’t getting any better after a few days, make an appointment with a healthcare provider. You may have a more severe injury that requires treatment.

Sometimes, nail discoloration is a symptom of an underlying health condition.

ConditionType of discoloration
psoriasisyellow-brown spots under the nail
kidney failurewhite on the bottom half and pink on the top
cirrhosiswhite
pseudomonas infectionsgreen

Seek medical attention if your nail (or nail bed) also:

  • changes in shape
  • thickens
  • bleeds
  • swells
  • is painful
  • has discharge

When you apply nail polish to the surface of your nail, it can penetrate and stain deeper layers of keratin in your nail. Polish left on your nails for just one week can result in staining.

Red- and orange-colored nail polish are more likely to cause discoloration. Nail hardeners containing formalin, dimethylurea, or glyoxal can also cause discoloration.

How to treat it

The only way to get rid of nail polish-related discoloration is to take a break from painting your nails. Even a break of just two or three weeks can resolve the issue.

Yellow nail syndrome is a rare condition that causes your nails to turn yellow.

If you have yellow nail syndrome, your nails may also:

  • look curved or thick
  • grow slower than usual
  • have indentations or ridges
  • have no cuticle
  • turn black or green

Experts aren’t sure what causes yellow nail syndrome, but it tends to affect adults over the age of 50. It also often occurs alongside another medical condition, such as:

There’s no treatment for yellow nail syndrome itself, though it sometimes goes away on its own.

Toenail discoloration can also be a side effect of certain medications.

MedicationType of discoloration
chemotherapy drugsdarkening or white bands across the nail
rheumatoid arthritis drugs containing goldlight or dark brown
antimalarial drugsblackish blue
minocyclinebluish-gray
tetracycline antibioticsyellow

Getting rid of toenail discoloration can take a bit of time. But once you’ve addressed the underlying issue, there are several things you can do to prevent the discoloration from returning.

These include:

  • Wash your feet regularly and follow up with a good moisturizer.
  • Wear breathable shoes and moisture-wicking socks.
  • Make sure your shoes aren’t too tight.
  • Wear shoes when walking around public areas, especially locker rooms and pool areas.
  • Trim nails straight across and use a nail file to smooth the edges.
  • Use trusted nail salons that sterilize their tools after every use.
  • Change your socks regularly and don’t reuse dirty socks.
  • Wait until your feet are completely dry before putting on socks or shoes.
  • Don’t wear nail polish for more than two weeks at a time.