Tinea capitis is a fungal infection of the scalp, commonly called scalp ringworm. It primarily affects children and causes patchy hair loss, scaling, and sometimes painful, swollen areas on the scalp. The infection lives inside and around the hair shaft itself, which is why it requires oral medication rather than topical creams to clear.
What Causes It
Tinea capitis is caused by a group of fungi called dermatophytes, which feed on keratin, the protein that makes up hair and skin. The two main fungal groups responsible are Trichophyton and Microsporum species. In the United States and United Kingdom, Trichophyton tonsurans is the most common culprit. In parts of Europe, the Middle East, and Africa, Microsporum canis (often spread from cats and dogs) plays a larger role.
These fungi invade the hair shaft in one of two ways. In endothrix invasion, fungal spores multiply entirely inside the hair shaft while the outer layer of the hair stays intact. This pattern is typical of T. tonsurans. In ectothrix invasion, the fungus grows both inside and on the outside of the hair, destroying the outer cuticle. Microsporum species tend to follow this pattern. The distinction matters because it affects how the infection looks, how it’s diagnosed, and how contagious it is.
How It Spreads
The infection spreads through direct contact with an infected person or animal, or indirectly through contaminated objects like combs, brushes, hats, pillowcases, and towels. Fungal spores can survive on surfaces for months, making shared grooming tools a common route of transmission in households and schools. Children between the ages of 3 and 14 are most frequently affected, and outbreaks in schools and daycare centers are well documented.
To reduce the risk of spreading the infection within a household, avoid sharing combs, brushes, hats, helmets, hair accessories, and towels. Wash pillowcases and towels in hot water regularly. If the infection came from a pet, the animal needs treatment too, or reinfection is likely.
What It Looks Like
Tinea capitis doesn’t always look the same. It has several distinct presentations, and the appearance depends on the type of fungus involved and how your immune system responds to it.
Black Dot Pattern
This is the most common presentation in many populations. The fungus breaks the hair off right at the scalp surface, leaving behind small black dots (the broken hair stubs) within patches of hair loss. The surrounding skin may have mild scaling. Because the hairs snap off so close to the surface, the patches can look almost bald.
Gray Patch Pattern
This type creates round or oval patches of hair loss covered in a fine, grayish-white scale. The hairs within the patch appear dull and broken a few millimeters above the scalp. It’s more commonly associated with Microsporum infections and is the pattern most people picture when they think of scalp ringworm.
Kerion
A kerion is a severe inflammatory reaction to the fungus. It appears as a painful, boggy, swollen mass on the scalp that oozes pus. Lymph nodes in the neck often swell alongside it, and children may develop a low-grade fever. A kerion can be mistaken for a bacterial abscess, but it’s actually the immune system mounting an intense response to the fungal invasion. This is the form most likely to cause permanent scarring and hair loss if not treated promptly.
Favus
Favus is the rarest and most severe form. It produces thick, yellow, cup-shaped crusts on the scalp called scutula, along with deep-seated nodules and abscesses. It’s typically caused by a specific species called Trichophyton schoenleinii and can cause extensive, permanent hair loss if left untreated for a long period.
How It’s Diagnosed
A healthcare provider can often suspect tinea capitis from its appearance, but confirming the diagnosis usually requires one or more additional steps. A Wood’s lamp (a special ultraviolet light) can be helpful in certain cases. Microsporum species produce a characteristic blue-green fluorescence under this light, while Trichophyton schoenleinii glows a dull blue. However, the most common cause in many countries, T. tonsurans, does not fluoresce at all, so a negative Wood’s lamp exam doesn’t rule out the infection.
For a definitive diagnosis, a provider will typically take a scraping of scalp skin and broken hairs. These samples can be examined under a microscope to look for fungal spores and can be sent for a culture to identify the exact species. The culture takes a few weeks to grow, so treatment is often started based on the microscope findings and clinical appearance while waiting for results.
Treatment
Unlike most other fungal skin infections, tinea capitis cannot be cured with creams or shampoos alone. Because the fungus lives inside the hair shaft, oral antifungal medication is necessary to reach the infection. Treatment typically lasts 6 to 12 weeks depending on the medication used and the severity of the infection.
The most commonly prescribed oral antifungals work by accumulating in the hair and skin, making those tissues hostile to fungal growth. Your provider will choose a specific medication based on the likely fungal species, your age, and other health factors. The length of treatment is important: stopping early, even when the scalp looks better, often leads to relapse because spores can persist deep in the hair follicle.
Antifungal shampoos are frequently recommended alongside oral medication. They don’t cure the infection on their own, but they help reduce the number of fungal spores on the scalp surface, which lowers the risk of spreading the infection to others during treatment.
School and Daycare Attendance
Whether children need to stay home from school during treatment is a debated topic among specialists. The general consensus is that once oral and topical treatment has been started, children can return to school or daycare. Some experts recommend keeping children home for about one week after starting treatment if the infection is caused by a species that produces heavy spore loads on the outside of the hair (ectothrix pattern). For all other cases, most guidelines allow return to school as soon as treatment begins.
There is no need to wait until the infection is completely cleared, which can take months. The goal is to reduce contagiousness to a reasonable level while keeping children in school.
Risks of Delayed Treatment
Most cases of tinea capitis resolve completely with proper treatment, and lost hair regrows fully. The exception is when the infection triggers a strong inflammatory response, particularly in the form of a kerion or favus. These inflammatory types can cause scarring of the hair follicles, leading to permanent patches of hair loss. The longer a kerion goes untreated, the greater the risk of permanent damage. Occasionally, a kerion is misdiagnosed as a bacterial infection and treated only with antibiotics, which delays appropriate antifungal therapy and worsens the outcome.
Even non-inflammatory forms of tinea capitis can cause significant distress. Visible patches of hair loss and scaling on a child’s scalp can affect self-esteem and lead to social difficulties at school. Prompt diagnosis and treatment minimize both the physical and emotional impact of the infection.