Dandruff and scalp psoriasis are easily confused: both present with an itchy and flaky scalp, two symptoms that can leave many people feeling embarrassed and awkward in public. However, the two conditions are very different, with approximately 50% of adults affected by dandruff compared to 2 – 3% of adults who suffer from psoriasis . Understanding both conditions is the first step to accurately diagnosing a flaking scalp and getting people confident in their appearance once again.
In this article, we’ll cover the causes of dandruff and scalp psoriasis, how to tell them apart, how to treat both conditions and what else could be causing your flaking scalp.
Fungal dandruff, also known as seborrheic dermatitis, is a common skin condition marked by thick, oily, yellow-tinged flakes of skin shedding from the scalp. Seborrheic dermatitis is not serious and occurs when there is an overgrowth of Malassezia fungus on the scalp, which disrupts the normal cycle of skin cells.
Psoriasis is a chronic autoimmune condition that can affect skin all over the body including the scalp, but also commonly found on the lower back, elbows, and knees. With this condition, skin cells are overproduced too quickly. In this condition skin cells are replaced every 3-7 days instead of the normal 3 – 4 weeks. This results in a build-up of cells that present as flaky, scaly patches of skin .
Where dandruff is caused by a physical accumulation of matter on the scalp, psoriasis flakes are caused by a systemic issue with the body’s immune system. Dandruff is likely to flare up from time to time unless managed long-term, but psoriasis is a chronic condition that can severely impact people’s day-to-day lives. Therefore, effectively diagnosing your flaking scalp is key to effectively treating your symptoms.
Dandruff is often used to describe a flaking scalp regardless of the cause, but true dandruff is a medical condition caused by the Malassezia fungus. When there is an overgrowth of Malassezia on the scalp, it can lead to a yeast infection of the scalp. The normal cycle of skin cells is disrupted, causing the cells to be produced at a much faster rate than normal. These excess cells then accumulate and form distinctive flakes of dandruff .
Malassezia fungus naturally occurs on the skin, and the reason why people suffer increased numbers on the scalp is not known. However, studies have shown that Malassezia feeds on oils produced by sebaceous glands, encouraging its growth. Therefore, regular hair-washing is key to controlling dandruff  especially if you find that you have oily skin or an oily scalp.
New research has also shown a relationship between dandruff and high levels of the bacteria Staphylococcus capitis on the scalp, although more needs to be done to fully understand this and incorporate it into treatment .
Scalp psoriasis is a chronic autoimmune disorder that causes the development of lesions (also known as plaques) on the scalp, which shed small, silvery-white scales. These plaques are caused by a systemic issue with the body’s immune cells which causes skin cells to be overproduced.
Normally, skin cells are replaced every 3 – 4 weeks, whereas with psoriasis the cells are replaced every 3 – 7 days.
The cause isn’t fully understood but is often triggered by an injury, infection, or new medication. The condition is not contagious, but genetics are believed to play a part and you are more likely to develop it if a family member also experiences psoriasis.
There are a few subtle but discernible differences between dandruff and scalp psoriasis that can help you to work out which condition you have. As these differences are slight, you may need someone else to help examine your scalp or seek medical advice. Two key things to look for are:
Dandruff usually presents with large, oily, yellow-tinged flakes, while psoriasis appears as silver, powdery, scales that shed in small pieces
Psoriasis causes the development of scalp lesions (also called plaques) which can easily become sores or scabs. These are often itchy, but not always. Look for inflamed or discoloured areas of hardening skin surrounded by pale scales. On darker skin tones, psoriasis might look violet (purple) with gray scales (according to the National Psoriasis Foundation).
The cause of dandruff isn’t entirely understood, but many studies have shown that the condition is linked to an excess of the fungus Malassezia. When this fungus grows too quickly, the natural cycle of skin cells is disrupted, and cells accumulate into distinctive scalp flakes.
Most anti-dandruff products work to kill the excess Malassezia on the scalp. Anti-dandruff products are available in a variety of forms, including foams, gels, sprays, shampoos, oils, and more. There are a variety of medications that can help dandruff and so you may need to try out several products to find the one which best works for you. Treatment should be stopped immediately if you feel any itching or stinging.
Anti-dandruff products may include:
It’s vital that you read the instructions on each anti-dandruff treatment as many need to be left for at least 5 – 10 minutes on the scalp to work. It is also recommended that you apply products gently, massaging into the scalp. Scrubbing your scalp may bring an immediate self of relief but this will only further irritate the scalp.
Anti-dandruff products can cause dry skin on the scalp and so people should alternate between regular moisturising shampoos and medicated ones. You may also need to rotate or swap between two different dandruff products .
Additionally, dry skin can sometimes cause flakes to shed into your hair, appearing similar to both dandruff and scalp psoriasis. To tell the difference, look at the flakes. Dry skin dandruff will be delicate and white, and subside quickly after moisturising.
Often, people with fungal dandruff successfully treat the condition with an anti-dandruff shampoo and return to their usual products after it subsides. However, many people will experience a resurgence in their dandruff, which usually reoccurs long-term and flares up from time to time (especially during the winter months). Healthcare professionals recommend regular use of an anti-dandruff product long-term for effective treatment of the condition, even after symptoms subside.
There is no cure for psoriasis, but the symptoms can be managed with medication. Initial treatment involves topical medications (applied directly onto the skin) which will reduce redness, itching, and flaking, such as emollients or steroid creams. Black seed oil can also be an effective natural remedy.
Even with treatment, your skin may take over 8 weeks to fully heal after experiencing a flare-up of scalp psoriasis .
If topical treatment is ineffective or if you have severe psoriasis, your doctor may suggest more systemic treatments such as immunosuppressants or anti-inflammatories. Phototherapy can also successfully manage psoriasis symptoms, a treatment that involves focusing ultraviolet light on affected areas of the skin. Your doctor will evaluate your individual situation to decide the best course of action.
Neither dandruff nor scalp psoriasis causes permanent hair loss.
Scalp psoriasis can result in temporary hair loss, but this is a secondary symptom and is caused by patients forcibly itching their skin plaques . Some patients may also experience telogen effluvium as a result of the stress of psoriasis. This is also temporary hair loss, and the scalp will recover.
Extreme dandruff can similarly induce itching that results in temporary hair loss. It is unlikely people would notice a change in their hair condition unless they suffer from extreme dandruff long-term and repeatedly cause severe inflammation to their scalp through scratching. To avoid this, there are many at-home treatments that can help alleviate itching and burning of the scalp.
Find out more about the causes of an itchy scalp according to the NHS.
Many other conditions cause scalp flaking as a symptom. These include:
If you do not notice any change after consistent use of over-the-counter treatment, speak to your doctor about other causes. Medical professionals can often diagnose dandruff (or causes) from a description of symptoms, or they may need to examine or test a skin sample.
If you suffer from scalp-related medical problems that lead to hair loss and would like an expert’s opinion what how to treat it, book a consultation today with a qualified and experienced trichologist.
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