Round patch in the hair: when it is worth assessing

Finding a round patch in your hair overnight is frightening. The first internet search almost always leads to alopecia areata, and often that is what it is. But it is not the only possibility. A fungal infection, the habit of pulling out hair, a hairstyle, recent surgery or, more rarely, a condition that leaves scarring can look similar. And the treatment for some can make others worse: a corticosteroid cream, useful in alopecia areata, makes tinea worse.

In this article we explain what you may observe, which clues help to tell the causes apart and when you should seek help.

What to look at in a patch

Before the consultation, looking carefully at the patch (or asking someone to do so, in natural light) helps to give the doctor useful information. Also take a photograph with a size reference, such as a coin beside it.

Possible causes of a round patch

In most adults with a smooth, symptomless patch, the cause is alopecia areata. But the table shows why an assessment matters: several of these conditions need opposite treatments.

Scalp ringworm (tinea capitis): the outbreak that came from barbershops

For decades, scalp ringworm (tinea capitis) was seen as a disease of children. That is changing. In recent years, several European countries, including Spain and Germany, have described an increase in infections with a fungus called Trichophyton tonsurans in teenagers and young men.

At a clinic in Málaga, Galváñ-Pérez del Pulgar and Martin-Gorgojo (2024) described 29 cases between 2021 and 2023. Most were young men who had their hair cut with a fade at the nape and temples, done with electric clippers almost every week, and some relatives were infected at home. In Germany, a multicentre study also documented the emergence of this fungus, associated with barbershops with poor hygiene in disinfecting clippers, combs and blades.

How it presents

• Patches with scaling and redness on the nape and temples, which may look like dandruff, seborrhoeic dermatitis or psoriasis.
• Patches with black dots (hairs broken at skin level).
• Inflammatory forms, with spots, pus and swollen glands behind the ears.
• Sometimes few or no symptoms, in carriers who infect others.
• Some cases mimic alopecia areata.

Why corticosteroid makes it worse

In the Spanish study, some patients had previously been treated with corticosteroid creams, which made the lesions worse. Corticosteroid reduces local defences and lets the fungus grow, as well as changing the appearance of the lesion and delaying diagnosis (so-called "tinea incognito"). So never apply corticosteroid creams to a patch without a diagnosis.

Diagnosis and treatment

The diagnosis is confirmed with trichoscopy (corkscrew or comma hairs suggest tinea), direct examination and culture of hairs and scales. Treatment is with oral antifungals for several weeks, often combined with an antifungal shampoo, and should include assessment of household contacts. Antifungal creams alone do not reach the root of the hair. Very inflamed forms (kerion) can leave scarring if not treated in time.

At the barbershop

Choose places that clean and disinfect clippers, combs and blades between clients and use washed towels. If you have lesions, say so and postpone the haircut until treated.

Children, beard and eyebrows

In children

In children, the two most common causes of patches are tinea and alopecia areata, followed by trichotillomania. A patch in a child should always be assessed, because:

• tinea is contagious, requires oral antifungal treatment and can leave scarring if very inflamed;
• alopecia areata starting in childhood tends to be more persistent;
• trichotillomania can be a sign of anxiety that deserves attention.

Do not apply creams without a diagnosis and check whether other family members or colleagues have similar lesions.

In the beard

A round, smooth patch in the beard is often alopecia areata and may appear on its own, without patches on the scalp. If there is redness, spots, pus or scaling, it may be tinea of the beard, sometimes caught from animals, or folliculitis, which need different treatment.

On eyebrows and eyelashes

Loss of eyebrows and eyelashes can occur in alopecia areata, but also in thyroid disease, in frontal fibrosing alopecia (especially in women after the menopause, with a receding forehead line) or in those who have a habit of pulling out hairs.

Always deserves assessment.

When to get assessed, and how urgently

Assessment in the next few weeks

• A round, smooth patch, without symptoms, that appeared recently.
• Patches in the beard, without other signs.
• A patch that has not recovered in three months.

Assessment without delay (days)

What not to do at home

• Do not apply corticosteroid creams or "leftover ointments".
• Do not shave the area around it to "see better", and do not cut other people's hair with the same clippers.
• Do not share combs, brushes, caps or towels until there is a diagnosis.
• Do not start "miracle" supplements or oils that delay assessment.
• Do not blame yourself: in most cases, the person did nothing to cause the patch.

At the consultation

At Luxmed, the hair medicine consultation includes:

• Clinical history with the questions in the table above (time course, symptoms, barbershop, contacts, operations, habits).
• Examination of the scalp, beard, eyebrows, eyelashes and nails.
• Trichoscopy, which quickly distinguishes alopecia areata (yellow and black dots, exclamation-mark hairs), tinea (corkscrew and comma hairs), trichotillomania (hairs broken at different lengths) and signs of scarring. See Trichoscopy: the examination that shows the scalp.
• Additional tests when indicated: sampling for mycological examination, blood tests or, in selected cases, a biopsy.
• Treatment plan suited to the cause and follow-up photographs.

This article is for information purposes and does not replace a medical consultation. The results of any treatment vary from person to person.

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