Part 2: What Causes Dandruff? The exact cause of dandruff, also known as scurf or Pityriasis simplex capillitii is unknown. However, most experts do agree that it is not caused by poor hygiene. Causes may include, but are not limited to: Not enough hair brushing: People who do not comb and/or brush their hair regularly have a slightly higher risk of having dandruff. This is because they are not aiding the shedding of skin that combing and/or brushing provides. Yeast: People who are sensitive to yeast have a slightly higher risk of having dandruff, so it is logical to assume that yeast may play a part. Dry skin: People with dry skin tend to get dandruff more often. Seborrheic dermatitis (irritated, oily skin): People with seborrheic dermatitis are very prone to dandruff. Not enough shampooing: Some people say that if you do not shampoo enough there can be a buildup of oil and dead skin cells, causing dandruff. However, many experts doubt this is true. Certain skin conditions: People with psoriasis, eczema, and some other skin disorders tend to get dandruff much more frequently than other people. Some illnesses: Adults with Parkinson's disease and some other neurological illnesses are more prone to having dandruff and seborrheic dermatitis. Patients recovering from heart attacks and strokes, and some people with weak immune systems may have dandruff more often than other people. Reaction to hair or skin care products: Some people react to some hair care products with a red, itchy, scaling scalp. Malassezia: Malassezia is a fungus that lives on everybody's scalp. Generally, it will cause no problems at all. However, it can grow out of control. It feeds on the oils our hair follicles secrete. When this happens the scalp can become irritated and produce extra skin cells. These extra skin cells die and fall off; they mix with the oil from hair and scalp, and turn into what we see as dandruff. Diet: Some experts say that people who do not consume enough foods that contain zinc, B vitamins, and some types of fats are more prone to dandruff. Mental stress: Experts believe there is a link between stress and many skin problems. HIV: A study found that 10.6 percent of people with HIV have seborrheic dermatitis. Want to read more? Subscribe to one of our monthly plans to continue reading this article.