Toenail Color Changes: What Each Color Signals

What Does Toenail Color Tell You About Your Health?

Toenail color signals specific health conditions: yellow indicates fungal onychomycosis, green reflects Pseudomonas bacterial infection, and black or brown can signal either a subungual hematoma or melanoma. White discoloration may point to surface damage or systemic disease, while blue or red tones often relate to circulation or trauma.

Toenails don’t change color randomly. They change because something is happening under or on top of the nail. The key is knowing where the color lives and how it behaves over time. That context is what turns worry into clarity.

---

Why Nail Color Depth Matters More Than the Color Itself

Understanding nail plate localization

Before looking at individual colors, it helps to understand nail plate localization.

• Color on the dorsal surface (top of the nail) usually signals external issues like fungus, polish damage, or dehydration
• Color under the nail plate or in the nail bed often signals trauma, bleeding, inflammation, or systemic disease

This simple concept explains why some color changes are harmless and others need urgent attention. Surface problems are usually manageable. Deep color changes are not something to ignore.

---

Yellow Toenails: Fungus, Psoriasis, or Something Rare?

This YouTube video below by The Meticulous Manicurist Nail Tutorials explains how to treat yellow toenails effectively. It covers causes, care tips, and practical remedies to restore nail health. These insights highlight the importance of proper treatment to prevent complications.

Yellow is the most common toenail color change. In most cases, it’s caused by onychomycosis, a fungal infection . Dermatophytes break down keratin using enzymes, which leads to discoloration, thickening, and debris buildup called subungual hyperkeratosis.

In most cases, it’s caused by onychomycosis, a fungal infection. Dermatophytes break down keratin using enzymes, which leads to discoloration, thickening, and debris buildup called subungual hyperkeratosis.

Typical fungal signs:

• Yellow or yellow-brown color
• Thick, brittle nail
• Crumbly debris under the nail
• Musty odor in some cases
• Nail lifting (onycholysis)

The oil spot sign

A smooth, translucent yellow-orange patch that looks fluid-like is known as the Oil Spot or Salmon Patch. This is a classic sign of nail psoriasis, not fungus.

Psoriatic nails:

• Look glossy or wet
• Lack crumbly debris
• Often come with pitting or nail lifting

Yellow Nail Syndrome vs. fungus

There’s also a rare condition called Yellow Nail Syndrome. It looks different.

Key clues:

• Nails grow extremely slowly
• Cuticles are absent
• Nails are uniformly yellow and thick but not crumbly

What to do:
Crumbly thick nails usually mean fungus. Smooth yellow patches or absent cuticles need a different evaluation.

---

Black or Dark Brown Toenails: Bruise or Serious Warning?

Dark nails cause the most fear, and rightly so. The cause depends on movement and pattern. Subungual hematoma — blood trapped under the nail after trauma — causes black, purple, or brown discoloration.

Subungual hematoma

Blood trapped under the nail after trauma causes black, purple, or brown discoloration. This includes Runner’s Toe, where repetitive micro-trauma from hitting the front of a shoe causes bleeding, even without a single injury.

Important sign:

• The color moves forward as the nail grows

Toenails grow about 1 mm per month, so bruises may take 6–9 months to fully grow out.

The growth test

You can track this safely:

• Mark the top of the spot or take a photo with a ruler
• Recheck after 8 weeks
• If the spot has moved at least 2 mm, it’s blood
• If it hasn’t moved at all, the pigment is coming from the matrix and needs immediate evaluation

Subungual melanoma and Hutchinson’s Sign

Subungual melanoma is rare but serious.

Watch for:

• Longitudinal melanonychia (dark vertical stripe)
• Irregular borders
• Pigment spreading onto the cuticle or surrounding skin

This spreading is called Hutchinson’s Sign. It is the red-flag feature that separates a bruise from a surgical priority.

---

White Toenails: Surface Spots or Systemic Clue?

White discoloration is grouped under leukonychia, but not all white nails mean the same thing.

Punctate leukonychia

These are small white dots caused by minor trauma to the nail matrix.

• Very common
• Harmless
• Grow out with the nail

White superficial onychomycosis

• Chalky white patches on the surface
• Can sometimes be lightly scraped
• Caused by surface fungus

Terry’s nails

This pattern shows over 80% white opacity, with only a thin pink or brown band at the tip.

It has been linked to:

• Liver disease
• Kidney disease
• Certain metabolic conditions

What to do:
Small white dots are harmless. Uniform white nails covering most of the plate deserve medical discussion.

---

Green Toenails: A Bacterial Fingerprint

Green nails are not fungal.

They are caused by Pseudomonas aeruginosa, a bacteria that grows in moist pockets under lifted nails.

The green color comes from bacterial pigments:

• Pyocyanin (blue-green)
• Pyoverdine (yellow-green)

Together, these create the characteristic fluorescent green hue. Many people also notice a faint sickly-sweet smell, which is often missed.

What to do:
This requires antibacterial treatment and keeping the nail dry. Antifungals won’t fix it.

---

Red or Purple Nails: Trauma vs. Vascular Signals

Red or purple nails usually mean bleeding.

Splinter hemorrhages explained

These look like tiny red or brown lines under the nail. They resemble splinters because they follow the longitudinal dermal ridges of the nail bed.

Most common cause is trauma.
But if splinter hemorrhages appear on multiple nails at once, without injury, they can signal systemic vasculitis or inflammatory disease.

---

Blue Toenails: Circulation and Cold Response

Blue nails indicate cyanosis, meaning reduced oxygen delivery.

Peripheral cyanosis

• Nails turn blue
• Tongue stays pink
• Often linked to Raynaud’s Phenomenon, where small arteries overreact to cold

If the color returns to pink after warming up, it’s usually a vascular response.

Central cyanosis

• Nails and tongue both appear blue
• Signals heart or lung involvement
• Needs urgent evaluation

A quick check is capillary refill. Press the nail until white, release, and color should return within 2 seconds.

---

Toenail Color Signals at a Glance

Color	Primary Signal	Most Common Cause
Yellow	Fungal or psoriatic	Onychomycosis / Psoriasis
Green	Bacterial	Pseudomonas (pyocyanin + pyoverdine)
White	Surface or systemic	Leukonychia / Terry’s nails
Black/Brown	Blood or pigment	Bruise / Melanoma
Red streaks	Capillary bleeding	Trauma / Vasculitis
Blue	Oxygen or circulation	Raynaud’s / Cyanosis

---

Why Nail Matrix Involvement Changes Everything

Color changes that involve the nail matrix are more serious. The matrix controls nail growth. Damage here can cause permanent nail deformity.

Surface issues often resolve. Matrix problems don’t.

---

A Safety Note on Color Changes

For people with reduced sensation or circulation, nail color may be the only warning sign. Pain may not appear even when infection or tissue damage is present.

Any sudden color change, swelling, warmth, or drainage should not be ignored.

---

Final Thought

Toenail colors are signals, not guesses.

• Yellow usually means fungus or psoriasis
• Green points to bacteria
• White can be cosmetic or systemic
• Black needs movement tracking
• Blue and red raise circulation questions

Understanding where the color sits and how it changes over time is what separates reassurance from urgency.