What Causes Dandruff?

Dandruff is a common condition that causes small, white, or yellowish skin flakes to shed from your scalp. When too much oil is on your scalp, dead skin cells shed more quickly than usual, leading to dry flakes to collect in your hair or fall onto your clothing.

About 50% of adults worldwide experience dandruff at some point in their lifetime. Contrary to popular belief, poor hygiene does not actually cause dandruff. There are many possible causes, including an overgrowth of Malassezia yeast, products that irritate the skin on your scalp, and skin conditions like eczema, psoriasis, and ringworm (tinea capitis). Other factors, including stress, diet, neurological conditions, and environmental factors, can also lead to dandruff.

Malassezia Yeast Overgrowth 

Malassezia yeast is part of the skin’s natural microbiome (or, a community of bacteria, fungi, and viruses that naturally live in your skin). This type of yeast lives with other microbes on your skin and scalp without causing harm. The yeast feeds on sebum (oil) on the scalp, so when your scalp produces too much sebum, it can lead to an overgrowth of Malassezia.

As the yeast multiplies in numbers, it breaks down the oil on your scalp into oleic acid—a type of omega-9 fatty acid. In people sensitive to oleic acid, this triggers an inflammatory response on the scalp, which leads to the shedding of skin cells more quickly than usual. As a result, you may experience flakes and scalp itchiness associated with dandruff. 

Scalp Irritation 

Anything that irritates the skin on your scalp can cause dandruff. Various personal care products and environmental factors can lead to scalp irritation, including:

• Hair dyes 
• Unrinsed shampoo 
• Hot showers 
• Hair care products containing alcohol or ingredients you might be allergic to
  

Irritation and damage to the scalp trigger inflammation in your skin cells, which causes your body to produce more skin cells to repair the damage. As a result, dead skin cells shed more rapidly than usual, leading to the hallmark flakes and itchiness of dandruff.

Skin Conditions 

Some skin conditions can contribute to the development of dandruff. These include:

• Psoriasis: A chronic (long-term), autoimmune condition that causes scaly, raised, and inflamed patches on your skin. When psoriasis affects the scalp, it can lead to an accelerated turnover of skin cells and a build-up of these skill cells, which can cause dandruff to develop.
• Eczema: Several types of eczema can affect the scalp, causing dry, itchy patches of skin that can flake off. Scratching can further worsen scalp irritation and lead to more severe dandruff.
• Scalp ringworm: Tinea capitis, or scalp ringworm, is a fungal infection that can cause dry, itchy, flaking patches of skin on the scalp.

Is Dandruff Hereditary? 

If you have a family member with a history of dandruff, you may be more likely to develop the flakes yourself. Researchers have identified 487 genetic markers linked to an increased risk of having dandruff, but more research is needed to determine precisely how genes influence the development of these flakes.

Although having a close family member with dandruff may mean you are more likely to have it yourself, genetics are not the only determining factor. Other factors, including the hair care products you use or how stressed you're feeling, can also contribute to the development and severity of dandruff. 

Who Gets Dandruff? 

Almost anyone can get dandruff, as over half of the world's adult population has dandruff at some point in their lifetime. However, certain groups are more likely to develop dandruff based on age, sex, and ethnicity.

• Age: Dandruff tends to first develop during adolescence and early adulthood, with its prevalence peaking in the 20s and gradually declining as people age. Research suggests that hormonal changes during puberty increase sebum production on the scalp, which may contribute to the development of dandruff. 
• Sex: Dandruff is more common in people assigned male at birth than females.
• Ethnicity: People of all races can get dandruff, but studies show that it is more common in certain ethnic groups than in others. For example, one study found that Black people tend to be more prone to dandruff than white people.

Risk Factors 

Several other factors can increase your risk of developing dandruff, including:

• Stress 
• Fatigue
• Living in a cold, dry climate or a hot, humid climate 
• Consuming a diet high in sugar
• Having a neurological condition, such as Parkinson’s disease, stroke, or traumatic brain injury (TBI) 
• Drinking excessive amounts of alcohol
• Being an organ transplant recipient or living with a condition that causes a weakened immune system, such as HIV/AIDS or lupus

A Quick Review 

Dandruff is a common condition that causes dry flakes of skin to shed from the scalp. Increased oil (sebum) levels on the scalp cause skin cells to shed more quickly than usual, which causes the hallmark white flakes of dandruff to fall from the scalp and into your hair. Dandruff commonly develops during adolescence and early adulthood when hormones increase oil production on the skin and scalp. 

Many factors can contribute to the development of dandruff, including Malassezia yeast overgrowth, scalp irritation from certain hair care products, and skin conditions like eczema or seborrheic dermatitis. Anyone can develop dandruff, but certain factors can increase your chances, such as stress, living in a dry, cold climate, and heavy alcohol use.