Scalp fungus typically appears as round, scaly patches where hair has broken off or fallen out. Depending on the type, you might see anything from mild flaking that looks like dandruff to swollen, crusty masses that ooze pus. The medical name is tinea capitis, and it takes several distinct visual forms, each with its own telltale signs.
The Most Common Patterns
Scalp fungus doesn’t have just one look. It shows up in a few recognizable patterns, and knowing which one you’re dealing with helps you understand what’s happening beneath the surface.
Gray patch: This is the classic presentation. You’ll see round or oval patches of dry, grayish scale on the scalp. Hair in those areas doesn’t fall out completely. Instead, it breaks a few millimeters above the skin, leaving short stubs that look dull and coated in a fine gray film. The patches spread gradually outward and can range from the size of a coin to several centimeters across.
Black dot: In this form, the fungus invades the hair shaft itself, causing it to swell and snap right at the scalp surface. What’s left behind are tiny dark dots scattered across a patch of bare skin. Those dots are the broken hair stumps sitting flush with the scalp. At a glance, the area can look almost bald with a stippled, peppered texture. The surrounding skin is often scaly but not dramatically inflamed.
Dandruff-like (diffuse scaling): Some infections skip the obvious bald patches entirely. Instead, the scalp develops widespread, fine flaking that closely mimics dandruff or seborrheic dermatitis. There may be mild itching and redness but no dramatic hair loss. This version is easy to miss or treat with the wrong products for months before the real cause is identified.
When It Gets Inflamed: Kerions
Sometimes the immune system mounts an aggressive reaction to the fungus, and the result is a kerion: a large, boggy, tender mass on the scalp. A kerion looks alarming. It’s swollen, spongy to the touch, and often covered in pustules and thick crusting. It can ooze pus, which leads many people (and even some clinicians) to mistake it for a bacterial abscess.
Kerions are painful, and the surrounding lymph nodes in the neck often swell as well. The intense inflammation can damage hair follicles permanently, so this form carries the highest risk of scarring hair loss. If you notice a raised, mushy, painful lump on the scalp that’s leaking fluid, that’s the version that needs prompt attention.
Favus: The Rarest Form
Favus is uncommon in most of the developed world but worth knowing about. It produces yellow, cup-shaped crusts called scutula, each one pierced by a single hair in the center. The name comes from the Latin word for “honeycomb,” and that’s a fair description: as the crusts grow and merge, they form a thick, waxy, yellowish mat over parts of the scalp. A distinctive musty or mouse-like odor often accompanies it. Left untreated over a long period, favus causes permanent scarring and hair loss.
How It Differs From Dandruff and Psoriasis
All three conditions cause a flaky, itchy scalp, which is why they get confused. The key differences come down to hair loss, patch shape, and scale quality.
- Scalp fungus produces defined round patches, often with visible hair breakage or bald spots. The scale tends to be grayish or dull, and the patches have relatively clear borders.
- Dandruff causes diffuse white or yellowish flakes across the entire scalp. It doesn’t cause hair loss, and the flakes tend to fall easily onto clothing and hair.
- Scalp psoriasis creates thicker, silvery or powdery plaques that often extend past the hairline onto the forehead, behind the ears, or down the neck. Psoriasis patches are raised and well-defined but don’t typically break hair shafts the way a fungal infection does.
The simplest distinguishing feature is hair loss. If you’re seeing patchy bald spots or broken hairs alongside scaling, fungus is the most likely explanation. Dandruff and psoriasis cause irritation and flaking but leave hair intact.
How Doctors Confirm It
A doctor can often suspect scalp fungus just by looking at it, but confirmation usually involves one of two methods. The first is a Wood’s lamp, a handheld UV light used in a darkened room. Certain fungal species cause infected hairs to glow blue-green under this light. Not all species fluoresce, though, so a negative result doesn’t rule it out.
The more definitive approach is taking a sample. The doctor scrapes some scale or plucks a few broken hairs from the edge of a patch and sends them to a lab, where the fungus can be identified under a microscope or grown in culture. Culture results can take a few weeks, but they confirm exactly which organism is involved.
Who Gets It and How It Spreads
Scalp fungus is overwhelmingly a childhood infection. It’s most common between ages 3 and 14, and it spreads easily through direct contact, shared combs, hats, pillows, and even upholstered furniture. Adults can carry the fungus without symptoms, which is one reason it circulates through households and schools. Adult infections do occur but are less common, and they tend to appear in people with weakened immune systems.
What Treatment Looks Like
Unlike fungal infections on the body’s surface, scalp fungus can’t be cleared with topical creams alone. The fungus lives inside the hair shaft and follicle, so oral antifungal medication taken over several weeks is the standard treatment. Most courses run 4 to 8 weeks, depending on how the infection responds.
A medicated shampoo is often used alongside the oral medication. The shampoo doesn’t cure the infection on its own, but it reduces the amount of fungus on the scalp surface, which helps limit spread to other people. During treatment, you don’t need to shave the head or keep a child home from school, but avoiding shared hair tools and headwear is important.
Hair regrowth in the affected patches typically begins once the fungus is cleared. In most non-inflammatory cases, hair comes back fully. Kerions and favus carry a higher risk of permanent bald spots due to scarring, particularly if treatment is delayed.