What Is Scalp Seborrheic Dermatitis?

Scalp seborrheic dermatitis, or SSD for short, is a type of eczema on the scalp (the skin on the head). The scalp becomes scaly and red with some inflammation (a bit like swelling). The authors say that this condition is the most common cause of an itchy scalp. It can last for a long time, and come and go: sometimes bad, sometimes barely there.

SSD happens most often to newborn babies (up to 3 months old) and adults aged 30 to 60 years old. When it happens to babies, it is known as cradle cap. Men are more often affected than women. It affects all ethnicities equally.

SSD happens more to people with immune system problems (those who are immunosuppressed). Because of this, scientists think that the immune system is involved with causing the problems.

What Isn’t SSD?

There are some scalp problems that are quite similar, but are in fact different conditions and causes, which need different treatment.

1. Dandruff (known as pytiriasis sicca) happens to many people. It involves a scaly scalp, but, unlike SSD, there is no inflammation.
2. Psoriasis is a skin condition that happens not only to the scalp but to skin all over the body. The skin has thick, silvery scales which could be mistaken for SSD if on the scalp.
3. Sebopsoriasis is another skin condition which overlaps between SSD and psoriasis.
4. Tinea capitis causes scaly, red, raised patches on the head but, unlike SSD, they are ring-shaped, and caused by ringworm.

To be sure what the skin problem is, the scalp and hair can be examined in close-up using a special handheld video camera.

How Did the Authors Gather the Required Information?

The authors performed a literature search to gather as much information as they could about SSD. A literature search involves searching through published medical reports and research results. This could take quite some time, if it was done manually, and important information could easily be missed. Fortunately, there are computer and internet systems and resources to make this easier. There are also official scientific methods of going about a literature search to make sure that nothing is missed, and all information is fairly treated.

In this case the authors looked for SSD studies that explored causes, the relation to skin microbiota, hair and new treatments. They found 19 articles, 4 of which were also review articles like theirs, 4 of which were clinical trials (high-quality scientific tests on people with the condition), and the others were minor types of research such as information on an individual patient (case reports).

Next, the authors divided the information found into 2 themes for their paper. In the first section they describe what they found about the causes and symptoms of SSD and in the second section they describe treatments.

What Did the Authors Say about the Causes of SSD?

Like so many health problems, the authors described how many issues can mix together to result in SSD. These include:

1. Changes in the skin microbiome. The microbiome is the normal mix of fungi and bacteria found on the skin. There is a skin fungus called Malassezia spp. that, although always in healthy skin, can become too strong. It interacts with the skin cells (called keratinocytes) and the immune system to result in changes to the skin’s natural lipid (fat) balance. This then results in changes to the skin.
2. Hormone problems can also cause SSD. It was discovered that people who have Parkinson’s disease are usually affected by SSD. Parkinson’s disease is a brain condition that affects movement and is due to not making enough of a hormone called dopamine. Also, SSD can start at puberty, which is an additional clue that hormones are part of the cause.
3. Not eating enough zinc can contribute to the inflammation part of SSD. Zinc is found in fruit and vegetables.
4. Environmental conditions such as high humidity, cloudy days, and low temperatures have also been linked to SSD.

Is There Treatment for SSD?

Yes, there are some treatments. Treatments depend on how bad the SSD is.

Treatment for mild SSD is called topical treatment, meaning that the treatment goes directly on the affected scalp skin area. This is in the form of creams, shampoos or lotions. They can reduce the levels of fungus or bacteria (antifungal and antibacterial), reduce the inflammation (corticosteroid), or reduce the skin thickness (keratolytics).

Treatment for severe or large areas of SSD is done with medicine taken by mouth (oral medicine). The medicine has similar effects to the topical medicine, but in different strengths and with different lasting effect. For example, some can stay in the body for up to two weeks, which can really help a bad case of SSD to improve (compared to a cream, which may rub off quickly).

Take-Home Message

If you are worried about your scalp skin health, you should ask a doctor to confirm what the problem is. For SSD there are treatments available. If the SSD is severe or complex, then testing of the scalp skin and hair can help guide treatment.