A kerion is a large, pus-filled sore caused by a fungal infection. It usually appears on your scalp. It may look yellow or crusty, ooze pus, feel soft to the touch and cause hair loss. Oral antifungal medications treat the fungal infection.
A kerion (keer-ee-on) is an inflammatory, pus-filled sore (abscess) that sometimes oozes. Kerions form when your immune system overreacts to the fungal infection ringworm (tinea corporis). They most often appear on your scalp, but they may also appear on your face, neck, shoulders and upper arms.
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Kerions can affect anyone. However, they most commonly affect children.
Kerions are large, thick, inflamed, swollen abscesses. Without treatment, kerions can cause scarring and permanent hair loss (alopecia).
Kerions can make you worry about how others look at you. They can also affect how you think about yourself and your behavior. You may become self-conscious or experience stress, anxiety and depression.
Kerion symptoms include:
Yes, kerions can be painful, given the inflammation and stretched skin.
Dermatophyte fungal infections (tinea capitis) cause kerions. Dermatophytes react with keratin in your hair, nails and skin. The most common fungi that cause ringworm in your scalp include:
Yes, kerions are contagious, and they commonly spread through skin-to-skin contact with an infected person or animal.
It’s a good idea to wash your hands after petting animals. It’s also a good idea to avoid sharing certain personal items if you have a kerion, including brushes, combs, hats, towels and bedding.
Kerions are contagious for several weeks, even with proper treatment. Without treatment, kerions may enlarge and keep spreading.
Follow your healthcare provider’s instructions. It’s important to finish your full course of medicine to make sure your kerion goes away and doesn’t come back.
Your healthcare provider will ask about your symptoms and perform a physical examination. They’ll look at your abscess, as well as your hair, skin and scalp.
They may want to collect a sample from your sore. They may collect hairs or pus or scrape a tiny amount of skin off (biopsy). A lab technician will then test the samples.
Your healthcare provider may order tests to confirm the presence of ringworm. These tests may include:
Your healthcare provider will gently scrape some of the skin from your affected area. They may also pluck some hairs or collect pus. They’ll send the samples to a lab for testing. A technician will then place the samples onto a microscope slide. The slide contains drops of potassium hydroxide (KOH) solution. KOH solution dissolves the skin cells so the technician can see if there’s a fungus present. The results are usually back within 24 hours.
A culture is a substance that allows fungi to grow. A technician can then identify the fungus responsible for your kerion. A culture is more accurate and specific than a KOH strain, but it may several weeks to get the results.
A Wood’s lamp is a special type of ultraviolet (UV) light. Your healthcare provider will shine a Wood’s lamp onto your scalp. Sometimes, ringworm glows under UV light. A glow may help your healthcare provider determine the type of fungus causing the ringworm. Your kerion may glow a yellow, green or blue color.
Your healthcare provider will likely prescribe oral antifungal medications to treat a kerion, such as:
A full course of treatment is usually six to eight weeks.
Your healthcare provider may also prescribe an oral corticosteroid (steroid). Steroids help reduce inflammation and lower the risk of scarring and hair loss.
To help prevent ringworm from spreading, your healthcare provider may prescribe a ketoconazole or selenium sulfide shampoo. However, it won’t kill the fungus. You may have to wash your hair with the shampoo at least twice a week.
No, you can’t use a topical antifungal medication to treat a kerion. Topical antifungal creams, ointments, gels and sprays that you rub on your scalp aren’t effective.
No, there aren’t any home remedies for a kerion.
With proper diagnosis and treatment, your kerion should go away in six to eight weeks. Many people begin feeling relief after two weeks. But be sure to complete the full course of your prescribed medication.
Your hair will usually grow back after treatment, though some hair loss may occur.
There are many ways to reduce your risk of getting a kerion:
Kerions can be difficult to cure. They share many of the same symptoms as tumors and bacterial infections, so they’re sometimes misdiagnosed. The longer you have a kerion, the more likely you are to have scarring or permanent hair loss.
If you have a kerion, you should check everyone else in your household for a fungal infection, including any pets. Ringworm is very contagious, so it’s a good idea to check close contacts and family members. They may need treatment, even if they don’t have symptoms.
Avoid touching your kerion. If you must touch it, wash your hands with antibacterial soap and warm water to avoid spreading the fungus to other people, animals or surfaces. In addition, regularly wash your pillows, bedding, towels and headwear. Clean, disinfect or replace brushes, combs, hair ties and other hair tools.
Call your healthcare provider if:
A note from Cleveland Clinic
Kerions can be uncomfortable and painful, and they can make you feel self-conscious about your appearance. It’s important to follow your healthcare provider’s treatment plan, which may take up to eight weeks. If you don’t finish your full course of medicine, kerions can come back and may even be more challenging to treat. If your kerion doesn’t go away, contact your healthcare provider.
Last reviewed by a Cleveland Clinic medical professional on 04/27/2022.
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