Introduction

Your scalp is the thick skin on top of your head, often covered in hair. Maybe you were running your hand through your hair when you felt something on it? Maybe your comb irritated something on your scalp when you were brushing it? Maybe your barber mentioned something when he was cutting your hair ? Changes to your scalp might be hard to identify, especially if they're at the back of your head or covered by hair, but if your scalp is feeling different, it's important to check what’s causing it. 

This article will focus on distinguishing between kerion and tinea capitis, two arguably connected rashes that can affect the scalp.

What are tinea capitis and kerion?

Tinea capitis

Tinea Capitis, also known as ringworm, is a fungal infection on the scalp that can be caused by organisms such as Microsporum and Trichophyton. It can affect anyone, but is most common in children aged 3 - 14 years old. 

Tinea capitis can be separated into 2 groups: 

1. Inflammatory - May lead to hair loss and a pimple containing pus (abscess), also known as Kerion
2. Non-inflammatory - unlikely to be complicated by hair loss¹

Kerion

Kerion is an extreme version of tinea capitis, perhaps caused by an extreme sensitivity to the fungal infection. It is identified by its inflammation and pus-filled pimples. Kerion can be a few centimetres long and hair within the kerion region becomes loose, leading to hair loss²

How are they caused?

Tinea capitis and kerion are both caused by the same fungi, which are able to infect the skin and hair. The fungus usually gets passed on from someone or something who is already infected, such as another person, an animal, soil or from an object, including sharing of hair brushes and hats.¹

Once the fungus is on your skin, it begins to grow down into the layers of your scalp and hair, weakening the hair follicles, triggering them to break and fall out.¹ Different fungi can affect different parts of your hair.

If you have a weakened immune system, the fungus will find it easier to grow, turning into kerions and making it easier for hair to fall out. 

Having a pre-existing medical condition such as diabetes, anaemia, or cancer could also affect the ease with which the fungus spreads. Similarly, the use of medication which lowers your immune system, such as steroids, could also have an effect.¹

What do they look like?

How does tinea capitis present

Symptoms of kerion include: 

• Large, thick, pus-containing pimples
• Squishy if you touch it
• Pus leaking from the hair follicles
• Raised and crusty skin
• Red
• Itchiness
• Pain
• Hair loss
• Fever
• Swollen lymph nodes in the neck

Diagnosis

Your doctor will want to investigate the tinea capitis and kerions to confirm their diagnosis. Some other skin conditions may look similar, such as cellulitis, infected eczema or psoriasis¹

They may take a swab from the infected area to have it tested, including testing the pus or hairs.

Different tests include:

1. The Potassium Hydroxide (KOH) test dissolves skin cells from the collected sample to identify the presence of a fungus and usually has a result within 24 hours
2. The Culture test lets the fungus grow so that it can be identified and therefore treatment targeted towards the right strain of fungus; however, it can take a few weeks before results are revealed
3. Shining ultraviolet (UV) light onto the affected area from a source called a Wood’s lamp can reveal what type of fungus is causing the infection, as sometimes the fungus will glow. The kerion may glow yellow, green or blue

Complications

Treatment options

Both Tinea capitis and kerion require oral antifungal medication for treatment. This would have to be prescribed by your doctor or dermatologist; they are not available for purchase over the counter. 

Examples of oral antifungals include griseofulvin, itraconazole, fluconazole or terbinafine. They are generally well tolerated, but common side effects include temporarily having an upset stomach (e.g. nausea, vomiting, diarrhoea), headache or sometimes a rash. Treatment is usually for 8 weeks, but will vary depending on your response to it - sometimes treatment will continue for longer to ensure it is completely gone.

In addition, your doctor may suggest applying an antifungal cream or shampoo to the affected scalp area, too. This would be alongside the oral treatment, not instead of it, to prevent the rash from spreading. These application-based treatments would contain antifungals such as Ketoconazole or Miconazole.

If you have a kerion, steroids may be prescribed to help bring down the redness and swelling. Steroids are usually prescribed as a short course and may also reduce the chances of any hair loss being permanent. 

If the tinea capitis or kerions have become infected with bacteria, then antibiotics might be prescribed.^2,3

Outlook

Tinea capitis is easily treated, especially if it is identified earlier. As long as you take your medication exactly as prescribed, for as long as your doctor recommends, your chances of clearing up the rash are high. 

If you delay seeking help, stop taking your medication before it finishes, or miss a lot of doses, you risk the tinea capitis turning into infected pimples called kerion¹. 

Kerions can be harder to treat, especially if you’ve had them for a while. It becomes harder for the skin to heal, potentially leading to permanent hair loss and scarring³.

Prevention and considerations

What to consider to stop the fungus from spreading from one person to another:

• Wash pillows, bed linen, towels, hats, caps, scarves or any other items that come into contact with the infection
• Wash and disinfect or replace combs, hair brushes, hair bands or anything else used around the infection
• Avoiding sharing combs, hats, etc
• Everyone living in the same house and other close contacts should be checked for tinea capitis and treatment should be started to prevent the cycling of the infection from one person to another
• Use an anti-fungal shampoo or one containing selenium to treat the infection alongside other medication

Summary table

Remember:

1. The earlier you see your doctor, the faster treatment can be initiated, and the risk of complications is reduced
2. Do not share any personal items, as they may spread the infection 
3. If you have a new or changing rash, don’t delay seeking medical advice