White Spots on Toenails: Causes and When It's Fungus

You take off your socks and notice a white spot, or a few chalky patches, on a toenail. It doesn't hurt and you can't remember hurting it. Is it a vitamin problem? Fungus? Nothing at all?

The good news is that white spots on nails are very common and often harmless. The medical term for white marks on the nail is leukonychia, and it simply describes what the nail looks like rather than what caused it. Sometimes, though, white patches on a toenail are an early sign of a fungal infection. Here's how to think it through.

The most common causes of white spots

Minor knocks and pressure

Small white dots or short white lines are often caused by minor injury to the base of the nail, where new nail is made. On toenails this can come from stubbing a toe, tight shoes, or repeated pressure from sports and long walks. You may not remember the injury at all, because the mark only becomes visible weeks later as the nail grows. These spots are harmless and gradually move towards the tip as the nail grows out.

Nail polish and nail products

Leaving polish on toenails for weeks at a time can leave rough, chalky white patches on the surface once it's removed. Strong removers and some nail products can also dry out or irritate the nail. These marks usually fade once the nail has a break from polish and grows out.

Superficial fungal infection

One type of fungal nail infection sits on the top surface of the nail and shows up as white, chalky or powdery patches. It's found more often on toenails than fingernails. Unlike a spot from a knock, these patches tend to spread and merge over time rather than simply growing out. The American Academy of Dermatology (AAD) describes this type of nail fungus as white colour that develops on the surface of the nail, which may feel soft, dry and powdery.

Nail lifting

When part of a nail separates from the skin beneath it (onycholysis), that area usually looks white or opaque. According to the AAD, common causes include a fungal infection, psoriasis and injury. A lifted area is usually at the tip or sides rather than a dot in the middle of the nail.

Psoriasis and other skin conditions

Nail psoriasis can cause white or yellow discolouration, lifting and crumbling. If you have psoriasis elsewhere, or several nails are affected, mention it to your healthcare provider. Our checklist on nail fungus vs. psoriasis covers the differences.

Changes across the whole nail

Less commonly, whitening of most of the nail, or white bands running across several nails at once, can be linked to health conditions elsewhere in the body. These patterns are different from a few scattered spots and are worth showing to a doctor.

What about vitamins and minerals?

Many people have heard that white spots mean a lack of calcium or zinc. That's a popular belief, but small white spots on otherwise healthy nails are much more often caused by minor injury than by a deficiency. If you have other symptoms, such as tiredness, hair loss or changes in many nails, talk to a healthcare provider rather than starting supplements on your own.

Signs a white spot might be fungus

These features make fungus more likely:

• The patches look chalky, powdery or crumbly rather than smooth.
• They're getting bigger or joining together over weeks to months.
• More than one toenail is involved, or the nail is starting to thicken or turn yellow.
• You have, or recently had, athlete's foot.
• You often walk barefoot in shared showers, pools or change rooms.

If several of these apply, it's worth finding out rather than waiting. Early, limited infections are generally easier to deal with, and the AAD notes that a cure is more likely with early treatment. A simple at-home qPCR test can tell you whether fungal DNA is present before you buy anything to treat it.

Signs it's probably not fungus

• One or a few small, smooth white dots or short lines.
• The spots move forward as your nail grows and eventually reach the tip.
• The rest of the nail looks normal: not thick, yellow or crumbly.
• You recently wore tight shoes, played sports, or had a knock to the toe.

A simple watch-and-compare trick

Toenails grow slowly, so changes take time to show. Take a clear, close-up photo of the nail in good light, and take another one in about a month in the same light. Spots from a minor knock should look the same or have moved slightly towards the tip. Fungal patches tend to grow, spread or multiply. Photos also help a healthcare provider see how things have changed.

When to see a healthcare provider

Book an appointment with a family doctor, nurse practitioner, podiatrist or chiropodist if:

• The white area is spreading, or the nail is thickening, lifting or crumbling.
• Most of the nail, or several nails, have turned white.
• You have pain, redness, swelling or pus around the nail.
• You have diabetes, poor circulation or a weakened immune system. Any foot or nail change deserves an early check (see toenail fungus and diabetes).
• You notice a dark streak or dark spot rather than a white one. Read toenail fungus or a bruise? for warning signs.

Why testing beats guessing with white spots

White spots are a good example of why appearance alone can mislead. A harmless knock, polish damage, nail lifting and an early fungal infection can all look like "white marks". Treating every white spot as fungus can mean months of using a product you didn't need, while ignoring a real infection lets it spread.

Our at-home kit lets you clip a sample of the affected nail and mail it back in the prepaid envelope. Your sample is analysed with qPCR DNA testing and reviewed by a licensed Canadian podiatrist with over 50 years of experience, and your written report arrives 4–14 days after your sample reaches us. See what a report looks like in our sample report, and read understanding your results to know what each outcome means. For more on timing, see when to get tested for nail fungus.

Frequently asked questions

Are white spots on toenails a sign of calcium deficiency?

Usually not. Small white spots on otherwise healthy nails are much more commonly caused by minor injury to the nail. If you have other symptoms or changes across many nails, talk to a healthcare provider instead of guessing with supplements.

Do white spots on toenails go away on their own?

Spots caused by a minor knock or by nail polish usually grow out with the nail. Because toenails grow slowly, this can take many months. White patches caused by fungus don't simply grow out and tend to spread over time.

Should I scrape white spots off my toenail?

It's best not to dig at or file down a nail yourself, especially if you have diabetes or poor circulation. You could damage the nail or the skin around it. If you think the patches might be fungal, get them checked or tested first.

Can nail polish cause white spots on toenails?

Yes. Wearing polish for long stretches can leave chalky white patches on the nail surface when it's removed. These usually improve once the nail has a break from polish. Polish can also hide early changes, so check your bare nails now and then.

How can I tell if white spots on my toenails are fungus?

Patches that are chalky, spreading, or joined by thickening or yellowing are more suspicious for fungus, especially if you've had athlete's foot. The only way to know for sure is to have the nail tested, for example with a qPCR DNA test, and discuss the result with a healthcare provider.

Sources

• American Academy of Dermatology: Nail fungus, signs and symptoms
• American Academy of Dermatology: 12 nail changes a dermatologist should examine
• American Academy of Dermatology: Nail fungus, causes
• NHS: Fungal nail infection
• Canadian Dermatology Association: Nail fungus and infection
• Mayo Clinic: Nail fungus, symptoms and causes