Nail fungus typically starts as a white or yellow-brown spot under the tip of a fingernail or toenail. As the infection spreads deeper, the nail thickens, discolors, and begins to crumble or fray at the edges. What it looks like depends on how far along the infection is and which type of fungus is responsible, but the progression from a small discolored spot to a distorted, brittle nail follows a fairly predictable pattern.
Early Signs of Nail Fungus
The first thing most people notice is a small spot of white or yellowish-brown discoloration near the tip of the nail. At this stage, the nail still looks mostly normal. You might dismiss it as a scuff mark or minor damage. But unlike a scratch or stain, a fungal spot doesn’t grow out with the nail. Instead, it stays in place or slowly expands.
Shortly after the discoloration appears, the nail may start losing its natural shine. The texture near the affected edge can become slightly rough or uneven, and you might notice the nail feels thicker than usual when you clip it. These early changes are subtle enough that many people don’t seek treatment for months.
How It Looks as It Progresses
Once the fungus works deeper into the nail, the changes become harder to ignore. The nail thickens noticeably and takes on a yellow, brown, or cloudy white color that spreads from the tip toward the base. Debris, a chalky buildup of dead skin cells and keratin, collects underneath the nail and pushes it upward, making it look raised or humped.
The edges of the nail become brittle, crumbly, or ragged. Pieces may break off unevenly, leaving a jagged outline. The nail can also become misshapen, curving or warping in ways it didn’t before. In some cases the nail separates from the nail bed underneath, creating a gap that looks hollow or discolored. This separation often starts at the tip and works backward. An unpleasant smell is common at this stage, caused by the buildup of fungal debris and bacteria trapped under the lifted nail.
Different Types Look Different
Not all fungal nail infections look the same, because different fungi attack the nail in different ways.
The most common type starts at the free edge of the nail (the part you trim) and works inward toward the cuticle. This is the classic pattern: yellowing, thickening, and debris accumulating underneath. It accounts for the majority of cases and is what most people picture when they think of nail fungus.
A less common type appears as white, powdery, or chalky patches on the surface of the nail plate itself. Rather than burrowing under the nail, the fungus colonizes the top layer, creating opaque white islands that can eventually cover most of the nail. The surface feels rough if you run your finger over it.
A third type starts near the cuticle rather than the tip. It shows up as a whitish area at the base of the nail that slowly moves outward as the nail grows. This pattern is less common in otherwise healthy people and can be a sign of a weakened immune system.
Yeast infections, most often caused by candida, tend to affect the skin around the nail as much as the nail itself. The cuticle and surrounding skin become swollen, red, tender, and warm to the touch. Over time the nail develops ridges or waves, may turn yellow or green, and can become dry and brittle enough to detach from the nail bed entirely.
Advanced Nail Fungus
Left untreated for months or years, a fungal infection can destroy the entire nail. At this stage the nail is severely thickened, cracked in multiple spots, crumbly, and may be pulling away from the skin underneath. The color can range from deep yellow to brown to almost black. The nail may curve abnormally or become so distorted that wearing closed shoes is painful. In the worst cases, the nail crumbles away entirely or falls off.
What Nail Fungus Doesn’t Look Like
Several other conditions mimic nail fungus closely enough that even doctors sometimes need a lab test to tell them apart. Knowing the differences can save you from treating the wrong problem.
Bruise Under the Nail
A bruise (subungual hematoma) from stubbing your toe or dropping something on your finger creates dark purple or black discoloration under the nail. Fungal infections, by contrast, produce yellow, brown, or white discoloration. A bruise also grows out gradually with the nail over weeks to months and eventually disappears, while fungal discoloration stays put or spreads.
Nail Psoriasis
Psoriasis can cause thickening, discoloration, and separation from the nail bed, all of which overlap with fungus. The key visual difference is pitting: tiny dents or depressions scattered across the nail surface, which fungus doesn’t cause. Psoriasis also produces a distinctive “oil drop” sign, salmon-colored or reddish-brown patches visible through the nail plate. If you have psoriasis elsewhere on your skin, nail changes are more likely psoriasis than fungus, though both conditions can occur simultaneously on the same nail.
Simple Nail Damage
Repeated trauma from tight shoes or habitual picking can make nails thick, ridged, and discolored. The difference is that damaged nails tend to improve once the source of trauma stops, while fungal nails worsen steadily. Fungal infections also spread to neighboring nails over time, which simple wear and tear does not.
Toenails vs. Fingernails
Nail fungus is far more common on toenails than fingernails, and the appearance reflects that. Toenails tend to show more dramatic thickening and discoloration because they grow slowly (giving the fungus more time to establish itself) and spend hours in the warm, moist environment inside shoes. Fingernail infections are more often associated with yeast and may include redness and swelling around the cuticle, especially in people whose hands are frequently wet.
On toenails, the big toe is the most frequently affected. On hands, the infection often begins on whichever fingers are exposed to the most moisture. Regardless of location, the progression follows the same general path: discoloration, thickening, crumbling, and eventually distortion or loss of the nail if untreated.