Fungal Infection of the Hair (Hair Fungus)

What hair fungus is

The fungi that cause it are dermatophytes, a group that feeds on keratin, the protein in skin, hair and nails. The same group causes athlete's foot and ringworm of the body. In the scalp, they grow into and around the hair shaft. The hair weakens and snaps off at or just above the skin surface, leaving patches of stubble or bald spots. That is the origin of the phrase "hair-eating fungus".

Despite the name ringworm, no worm is involved. Doctors call scalp infection tinea capitis. Fungal infection of beard hair is called tinea barbae.

Two main species cause most cases:

• Trichophyton tonsurans: spreads between people. It is now the most common cause in the US and UK, especially in cities.
• Microsporum canis: caught from cats and dogs, sometimes rabbits and guinea pigs.

The fungus can live on combs, brushes, hats, pillows and furniture for months.

Symptoms

Scalp ringworm can look quite different from child to child. Common patterns:

Other signs:

• an itchy scalp, sometimes mild
• hair loss in one or several patches
• swollen glands at the back of the neck or behind the ears, which are a strong clue in a child with a scaly scalp
• an "id reaction": a small itchy rash elsewhere on the body as the immune system reacts, sometimes after starting treatment

Kerion

A kerion is a strong inflammatory reaction to the fungus. The swelling is painful and can look like an abscess, but it is not a bacterial infection, so cutting it open or using antibiotics alone does not help. It can leave permanent scarring and hair loss if it is not treated quickly with antifungal tablets.

Who gets fungal hair infections

• Children aged 3 to 9: before puberty, the scalp has fewer of the natural fatty acids that inhibit fungi.
• Close contacts: siblings, classmates, and children in daycare or sports with shared helmets.
• Pet owners: especially with new kittens or puppies.
• Adults: less common. When it happens, it is often in older women or people with weakened immunity, and it may be mistaken for other scalp conditions.

Conditions that look similar

Diagnosis

A primary care doctor or pediatrician can usually diagnose and treat it. A dermatologist sees difficult, recurrent or adult cases and kerion. The doctor will:

1. Examine the scalp, the neck glands, and the skin and nails elsewhere.
2. Take samples by gently scraping scale and plucking or brushing broken hairs.
3. Examine them under a microscope for fungal elements, and send them for culture, which identifies the species in 2 to 4 weeks.
4. Sometimes use a Wood's lamp (ultraviolet light). Microsporum infections glow green; the more common Trichophyton tonsurans does not, so a negative result does not rule it out.

Treatment is often started before culture results return when the picture is typical.

Treatment for hair fungus

Antifungal tablets

Because the fungus lives inside the hair shaft and follicle, creams cannot reach it. Oral antifungal medicine is essential. The main options:

• Terbinafine: usually 4 weeks or longer. Works best for Trichophyton.
• Griseofulvin: usually 6 to 8 weeks or longer. Works best for Microsporum. Take it with fatty food, such as milk or ice cream, to improve absorption.
• Itraconazole or fluconazole: alternatives in some cases.

Your doctor chooses the medicine and dose by weight and species. Finish the full course even if the scalp looks better, and the doctor may repeat the scrapings to confirm the infection has cleared. Blood tests for liver function are sometimes checked for longer courses or in adults.

Antifungal shampoo

Shampoos containing ketoconazole 2% or selenium sulfide do not cure the infection alone. Used 2 to 3 times a week, they reduce the number of fungal spores and so lower the risk of spreading it. Other household members may be advised to use them too.

Treating kerion

A kerion is treated with oral antifungals. Sometimes a short course of steroid tablets is added to calm severe inflammation. Antibiotics are used only if a secondary bacterial infection is confirmed.

Stopping the spread

• Do not share combs, brushes, hats, hair ties, towels or pillows.
• Soak combs and brushes in hot soapy water or a disinfectant, or replace them.
• Wash bedding and hats in hot water.
• Check everyone in the household. Family members, especially other children, may need scalp samples.
• Take pets with patchy fur loss to a vet.
• Children do not usually need to miss school once treatment has started, though local policies vary.

Complications

• Permanent scarring and hair loss, mostly after a kerion or favus left untreated.
• Secondary bacterial infection of open, scratched areas.
• Spread to the body, nails or other people.
• Side effects of medicine: stomach upset, rash, headache, and rarely liver problems. Griseofulvin can make skin more sensitive to sun.

Outlook

With the right antifungal tablets taken for the full course, most children are cured and hair grows back over several months. Recurrence usually means reinfection from a household member, a pet, or contaminated brushes and hats, which is why treating the source matters as much as treating the child.

Prevention

• Teach children not to share hats, helmets, combs and hair accessories.
• Wash hair regularly, and dry it well.
• Treat any pet with suspected ringworm.
• Treat ringworm on the body, feet or nails promptly so it does not spread to the scalp.

Frequently asked questions

What is the hair-eating fungus?

"Hair-eating fungus" is a popular name for scalp ringworm (tinea capitis). Dermatophyte fungi feed on keratin in the hair shaft, weakening hairs so they break off at the scalp, leaving scaly bald patches. It is common in children and treatable with antifungal tablets.

What is the best treatment for hair fungus?

Prescription antifungal tablets, usually terbinafine or griseofulvin, taken for at least 4 to 8 weeks. Antifungal shampoo such as ketoconazole or selenium sulfide is used alongside to reduce spread. Creams and shampoo alone will not cure an infection inside the hair shaft.

What type of doctor treats hair fungus?

Start with your primary care doctor or your child's pediatrician, who can take samples and prescribe antifungal tablets. A dermatologist (skin, hair and nail specialist) is the right referral for severe cases such as a kerion, infections in adults, or infections that keep coming back.

Does hair grow back after a fungal scalp infection?

Usually yes. Once the fungus is cleared, hair typically regrows over 3 to 6 months. Permanent bald patches are uncommon and mainly follow a severe, inflamed kerion that was not treated promptly, which is why early treatment matters.

Can adults get fungal infection of the hair?

Yes, but it is much less common than in children. Adults, especially older women and people with weakened immunity, can be infected, often by a child or a pet. It may be mistaken for dandruff or psoriasis, so samples for fungal testing are important.

Is scalp ringworm contagious?

Yes. It spreads by direct contact and through shared combs, brushes, hats, pillows and furniture, and from infected cats and dogs. Spores can survive for months on objects. Antifungal shampoo and cleaning shared items reduce the risk to others.