Not enough hair brushing – People who do not comb/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/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. Yeast-sensitive people who get dandruff find that it gets better during the warmer months and worse during the winter. UVA light from the sun counteracts the yeast. Some say, though, that during winter the skin is drier because of cold air and overheated rooms (exposure to extreme temperatures), making dandruff more likely. So, it is sometimes not that easy to know whether it is yeast or just dry skin.
Dry skin – people with dry skin tend to get dandruff more often. Winter cold air, combined with overheated rooms is a common cause of itchy, flaking skin. People with dandruff caused by dry skin tend to have small flakes of dandruff; the flakes are not oily.
Seborrheic dermatitis (irritated, oily skin) – People with seborrheic dermatitis are very prone to dandruff. Seborrheic dermatitis affects many areas of the skin, including the backs of the ears, the breastbone, eyebrows, and the sides of the nose, not just the scalp. The patient will have red, greasy skin covered with flaky white or yellow scales.
Not enough shampooing – some people say that if you don’t 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/skin care products – Some people react to some hair care products with a red, itchy, scaling scalp. Many experts say that shampooing too often may cause dandruff as it can irritate the 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 produces extra skin cells. These extra skin cells die and fall off; they mix with the oil from the 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% of people with HIV have seborrheic dermatitis.