The skin effects of psoriasis and seborrheic dermatitis can look similar. Some people may have both of these inflammatory conditions. However, these conditions have key differences, such as areas of appearance and triggers.
People often confuse psoriasis and seborrheic dermatitis as both can affect the scalp. One main difference between the two conditions is their appearance.
Psoriasis that affects the scalp appears powdery and has a silver surface. Seborrheic dermatitis is more likely to appear yellow and greasy.
This article looks at other differences between the conditions and their possible causes and treatments.
Understanding the differences between seborrheic dermatitis and psoriasis can help people get early treatment from a doctor.
The table below shows some differences between seborrheic dermatitis and psoriasis.
| Symptoms | Causes | Triggers | Risk factors | |
|---|---|---|---|---|
| Psoriasis | • often affects elbows and knees • raised, scaly patches • cracking, bleeding skin • dry skin • silver-white scales | • genetics and environment • autoimmune condition | • stress • skin injury • medications • infection | • equally common in males and females • often occurs at 15–35 years of age |
| Seborrheic dermatitis | • often affects the scalp • crusty, white flakes • greasy, yellow scales • discolored and swollen skin • itching or burning | • genetics and environment | • stress • hormone changes • chemicals • illness • solvents • soaps • harsh detergents • dry weather | • more common in young adults and adults over 50 years of age • more common in males |
Seborrheic dermatitis symptoms
The symptoms of seborrheic dermatitis usually develop on the scalp. However, they can sometimes develop on the face, upper chest, and back.
Symptoms include:
- crusty, white flakes
- greasy, yellow scales
- discolored and swollen skin
- an itching or burning sensation in the affected area
Psoriasis symptoms
While psoriasis can affect the scalp, it is more likely to develop in other areas of the body, such as the elbows or knees.
Psoriasis causes raised, scaly patches to appear on the skin. When it develops on the scalp, it can lead to cracking, bleeding skin, and silver-white scales. The skin may feel sore or have a burning sensation.
However, as with seborrheic dermatitis, psoriasis can also cause flaking that resembles dandruff. Despite this similarity, the skin around psoriasis lesions is much drier than the skin around sites that seborrheic dermatitis affects.
Learn about different types of psoriasis.
Scientists do not know the exact cause of psoriasis or seborrheic dermatitis. However, researchers believe that genetics play a critical role in both.
Triggers in the environment can activate specific genes that lead to dermatitis and psoriasis. This, in turn, causes these genes to send incorrect signals to the immune system.
Considering any recent exposure to these triggers can help a person identify which condition might be causing a symptom flare.
Triggers for seborrheic dermatitis
Seborrheic dermatitis triggers include:
- stress
- hormone changes
- chemicals
- illness
- solvents
- soaps
- harsh detergents
- dry weather
- microorganisms on the skin
Conditions that affect the immune system, such as HIV, can worsen the symptoms of seborrheic dermatitis. Those that affect the nervous system, such as Parkinson’s disease, might also worsen symptoms.
Triggers for psoriasis
When people have psoriasis, skin cells grow more quickly than usual. This causes lesions to build up.
Factors that can trigger a flare-up of psoriasis symptoms include:
- stress
- skin injury
- medications, such as lithium and quinidine
- an infection, such as strep throat, bronchitis, or tonsillitis
Read more about psoriasis triggers.
Genetics likely play a role in both psoriasis and seborrheic dermatitis. A person with a family history of either condition may be more likely to develop them when they experience certain triggers.
Seborrheic dermatitis can develop at any age, but the condition usually occurs in young adults or adults
Males and females are equally as likely to experience psoriasis. It is slightly more common in white people than in African Americans.
People can develop psoriasis at any age, although it often occurs between 15 and 35 years of age. In very rare cases, infants may develop psoriasis.
Several treatments are available for both seborrheic dermatitis and psoriasis. Treatments are different for each condition. The effectiveness of different approaches can vary from person to person.
Seborrheic dermatitis treatment
A person can help treat mild cases of seborrheic dermatitis by applying a topical antifungal cream. Medicated shampoo can also help.
Examples of these include:
People with more severe seborrheic dermatitis may need treatment with corticosteroids to help lower inflammation.
Corticosteroids may not be appropriate if someone has had previous, long-term exposure to them. If this is the case, a doctor might prescribe a topical calcineurin inhibitor (TCI) medication.
These treatments might also help some people with scalp psoriasis. However, doctors consider them to be off-label medications for psoriasis. Off-label use is when doctors prescribe a drug for a purpose other than what it’s approved for.
Examples of TCIs that a doctor may prescribe off-label include:
- tacrolimus (Protopic)
- pimecrolimus (Elidel)
People with severe seborrheic dermatitis might also use antifungal medication.
Scalp psoriasis treatments
Different types of psoriasis require different interventions. As seborrheic dermatitis most closely resembles scalp psoriasis, this article focuses on treatments for scalp psoriasis.
Treating scalp psoriasis is often complicated and takes time and patience.
Coal tar products and salicylic acid are useful for treating mild scalp psoriasis. Many medicated shampoos are available over the counter (OTC). These shampoos help treat scalp lesions and reduce itching if the lesions are very mild and only affect a few areas.
To help soften plaques, a person can try bathing the scalp in warm water or making the scalp damp before applying lotions, creams, and ointments. Gently combing the scalp in circular motions can then remove softened plaques from the scalp.
More severe cases of scalp psoriasis may require more intensive topical treatments, such as:
- anthralin (Dritho-Scalp)
- calcipotriene (Dovonex)
- calcipotriene and betamethasone dipropionate (Taclonex)
- tazarotene (Tazorac)
Doctors do not often consider systemic medications, which affect the whole body, as treatments for scalp psoriasis.
They may consider biologics, such as etanercept (Enbrel), that originate from living cells. However, these medications are not first-line treatments for scalp psoriasis, and doctors may prescribe them off-label.
People with more severe scalp psoriasis may need to try and combine several treatments before they find the one that works for them.
After repeated use, a person’s psoriasis may become less responsive to the medication. If this happens, they may need a combination of treatments, which they can use in rotation.
A person may need to talk with a doctor if they are experiencing the physical effects of seborrheic dermatitis or psoriasis. If a rash, lesion, or pustule does not respond to OTC remedies, it may be one of these chronic disorders.
Currently, no test is available to identify either condition. A doctor will ask people questions about their medical history and look at the lesions to determine the cause.
The doctor may also remove a small sample of skin to help confirm their diagnosis.
Seborrheic dermatitis and psoriasis can appear similar but present on the scalp in different ways.
Psoriasis is more likely to appear in other areas of skin alongside the scalp, and several different types may develop. Seborrheic dermatitis, however, tends to develop mainly on the scalp.
The appearance of psoriasis tends to change depending on the type. Seborrheic dermatitis, on the other hand, appears as yellow, greasy scales with discolored, swollen skin and white flakes.
Psoriatic plaques usually have a silvery surface that may cause itching and pain.
Different treatments are available, and a person may need to seek a medical opinion if they suspect the presence of either condition.