Seborrheic dermatitis and scalp psoriasis are two different skin conditions that can affect the scalp. Both conditions involve immune system overactivity, but they cause different symptoms.
Seborrheic dermatitis is a skin condition that causes a scaly rash on oil-producing areas of the body, such as the scalp and face. Dandruff is a very mild form of this condition.
Psoriasis is a chronic autoimmune disease in which skin cells multiply too quickly and build up on the skin, forming scaly, inflamed patches. Scalp psoriasis affects the scalp and nearby areas, such as the forehead, the area behind the ears, and the neck.
The two key differences between seborrheic dermatitis and scalp psoriasis are the causes and symptoms.
Seborrheic dermatitis typically occurs in response to excess levels of a yeast called Malassezia. This yeast usually lives harmlessly on the skin’s surface. However, it can sometimes multiply out of control, triggering an immune system overreaction that causes skin inflammation.
Scalp psoriasis
The immune system activity underlying the two conditions also differs. Whereas seborrheic dermatitis triggers an inflammatory response, scalp psoriasis triggers an overproduction of skin cells. As a result, the two conditions cause different symptoms.
Learn more about the difference between seborrheic dermatitis and psoriasis.
The symptoms of the two conditions are listed below.
Seborrheic dermatitis symptoms
Seborrheic dermatitis causes a skin rash that can present differently on different skin tones.
On dark skin, the rash may appear pink, purple, or lighter than the surrounding skin. On light skin, it may appear red. The rash may produce white or yellowish scales, which may be dry or greasy.
Seborrheic dermatitis may occur on any part of the body that has a lot of oil-producing glands, such as:
- on the eyebrows
- on the eyelids
- on the ears
- on the sides of the nose
- around the mouth
- on the back of the head and neck
- on the chest
Scalp psoriasis symptoms
According to the American Academy of Dermatology (AAD), scalp psoriasis can occur in small patches or extend across the scalp.
Symptoms of scalp psoriasis may include:
- reddish, inflamed patches on the scalp
- silvery-white scales that are prone to flaking
- patches of dryness, which may itch, crack, and bleed
- sensations of burning or soreness
- temporary hair loss
The symptoms may come and go and may range from mild to severe.
Below are some potential causes of each condition.
Seborrheic dermatitis causes
According to the AAD, scientists do not know exactly what causes seborrheic dermatitis. However, two factors that appear to play a role are Malassezia yeast and the oil that the skin produces, which is called sebum. Dermatologists believe that the Malassezia may feed on the sebum.
Although everyone has Malassezia on their skin, only some people will develop seborrheic dermatitis, and many of those people will be otherwise healthy. However, having one or more of the following health conditions can increase the risk of seborrheic dermatitis:
- certain neurological disorders, such as epilepsy and Parkinson’s disease
- brain trauma
- spinal cord injury
- HIV
- lymphoma
- psoriasis
- rosacea
- stroke or heart attack
- anorexia nervosa
- Down syndrome
- mood disorders such as depression
- excessive alcohol consumption
Scalp psoriasis causes
Scalp psoriasis occurs when an overactive immune system causes the skin cells to grow too quickly.
Instead of growing over weeks, the cells grow within days. The body makes the cells more quickly than it can shed them, causing layers of skin cells to pile up on the skin’s surface. This results in scaly patches of psoriasis.
Scientists
Certain external factors also appear to increase a person’s chance of developing psoriasis. These include:
- infections, especially streptococcal infections and HIV
- certain medications, such as some heart medications and antimalarials
- smoking
- obesity
The diagnostic processes for seborrheic dermatitis and scalp psoriasis are similar and relatively straightforward.
In both cases, a doctor will ask about a person’s symptoms and visually inspect any affected areas of skin.
In some cases, a doctor may take a skin culture to confirm the diagnosis. This involves scraping off a small piece of skin and looking at the cells under a microscope.
Below are the treatment options for each condition.
Seborrheic dermatitis treatment
While there is no cure for seborrheic dermatitis, treatments can help reduce signs of the disease and alleviate the symptoms.
Treatment options for seborrheic dermatitis on the scalp include:
- Dandruff shampoo: Milder shampoos are available over the counter, while stronger alternatives are available via prescription only. Some dermatologists may recommend using two or three shampoos.
- Medications to soften scales: Dermatologists may prescribe medications to help soften patches of skin that are covered in thick crusts. Depending on the severity of the patches, people may need to leave the treatment on their scalp for an hour or, in some cases, even overnight.
- Anti-inflammatory medications: Doctors may recommend these medications in the short term to help decrease skin swelling and discoloration. In cases of severe SD, a dermatologist may prescribe a topical corticosteroid to help manage the disease.
Scalp psoriasis treatment
The AAD lists the following treatment options for scalp psoriasis:
- topical medications such as lotions, creams, and ointments
- medicated shampoos
- scale softeners
- injectable medications that
suppress the immune system and slow down cell growth and division - light treatments
Other general treatments for psoriasis include:
- Biologic response modifiers: injectable medications that block specific immune molecules to help decrease or stop inflammation
- Immunosuppressants: medications that suppress the immune system in severe cases of psoriasis
- Oral phosphodiesterase 4 (PDE4) inhibitors: drugs that target enzymes inside immune cells and help suppress rapid skin cell turnover and inflammation
- Oral tyrosine kinase 2 (TYK2) inhibitors: drugs that block the activation of certain immune cells
A person should contact a doctor if they have a new or worsening rash on their scalp, particularly if they have received a diagnosis of seborrheic dermatitis or psoriasis in the past.
Both conditions can flare up repeatedly throughout a person’s lifetime.
A person should also contact a doctor if their rash shows signs of a possible infection, such as:
- pus
- yellow or golden crusts
- pain
- swelling
- warmth
- unpleasant odor
- red, purple, or brown skin discoloration
A severe infection may cause additional symptoms, such as swollen lymph nodes, fever, or chills.
Can seborrheic dermatitis turn into scalp psoriasis?
Seborrheic dermatitis and scalp psoriasis are two distinct skin conditions with different causes and symptoms.
An older
If a person has both conditions, doctors use the term “sebopsoriasis.”
What is triggering my scalp psoriasis?
Psoriasis has many possible triggers. According to the United Kingdom’s National Health Service (NHS), examples include stress, hormonal changes, and skin injury, such as a cut or an insect bite.
Learn about 12 triggers for psoriasis and how to avoid them.
Does seborrheic dermatitis go away?
Seborrheic dermatitis is most likely to occur during one of the following life stages:
- Infancy, between 2 and 12 months of age
- adolescence
- adulthood, typically beginning in a person’s 30s or later
In adolescents and adults, the condition can come and go for years and may last a lifetime. However, treatments can help relieve symptoms when they occur.
Seborrheic dermatitis and scalp psoriasis are two different skin conditions that can affect the scalp and other parts of the body.
Both conditions involve immune system overactivity, but the mechanisms of the overactivity differ. The two conditions also cause different symptoms.
Scientists believe that seborrheic dermatitis occurs when the immune system overreacts to the presence of a yeast that usually lives harmlessly on the skin. This can cause a scaly rash on oil-producing areas of the body, such as the scalp.
In scalp psoriasis, an overactive immune system causes skin cells to grow more quickly than the body can shed them. The cells pile up on the skin, forming scaly patches that may itch, crack, and bleed.
Treatments are available to help manage each condition and relieve the symptoms. The first step is to contact a doctor for a diagnosis, which is typically a simple and straightforward process.