Why dandruff occurs?

Why dandruff occurs?

The top layer of the skin is constantly being shed and renewed. This usually goes unnoticed when the cells are shed one at a time.

Inflammation of the scalp may cause cells to stick together. When large clumps of cells are shed, visible flakes may be seen on the shoulders especially when wearing dark clothing or on the scalp as the hair traps the scaling skin.

Dandruff (pityriasis capitis) is the term used to describe simple scaling of the skin on the scalp. About 50 per cent of the population suffers from dandruff at some point in their life. Regular washing with an anti-dandruff shampoo is useful in the treatment of dandruff.

Cradle cap is a form of seborrhoeic dermatitis that occurs in newborns. It may not be the same disease as in adults. It results in a thick, yellow-crusted scalp lesion.

Other symptoms can include:

  • splits in the skin and behind the ears
  • red facial pustules
  • stubborn nappy rash.

Older children can develop thick, stubborn plaques on the scalp, measuring one to two centimetres across.

Seborrhoeic dermatitis affects areas with high densities of large oil glands. The inflammation is caused by the body’s reaction to a yeast on the scalp and to products that break down oil produced by the oil gland.

The incidence and severity of seborrhoeic dermatitis seems to be affected by:

  • other illnesses – for example, people with neurologic disease (especially Parkinson’s disease, stroke and paralysis) or HIV may have severe seborrhoeic dermatitis
  • emotional or physical stress
  • genetic factors
  • seasonal – seborrhoeic dermatitis is usually worse in winter.

Symptoms of seborrhoeic dermatitis develop gradually and may include:

  • dry or greasy diffuse scaling of the scalp. This is the most usual presentation.
  • yellow-red scaling on those areas of the body that are generally affected in severe disease – along the hairline, behind the hair, on the eyebrows, on the bridge of the nose, in the creases between the nose and the lips inside the ears, over the sternum (middle of the chest), on the underarms and groin areas.


The most common anti-dandruff shampoos contain one or more of:

  • zinc pyrithione or zinc omadine
  • selenium sulphide
  • piroctone olamine – this is the most recent addition to the medicated shampoos. It is known as a ‘second generation’ anti-dandruff agent. It is less toxic than zinc pyrithione and is therefore safer for family use
  • antifungal agents
  • tar – shampoos containing tar have been used for years, usually for more severe scalp conditions. In the past, the scent of the tar-based shampoos made them less acceptable. However, newer preparations are well tolerated and simple to use.

Itching scalp

Itching scalp, with or without scaling, is very common. It may occur in middle-aged people, for no obvious reason. The usual response is to scratch, and this will often cause scratch marks and little crusty sores throughout the scalp. Dandruff can cause itching scalp. There are also a number of less common skin conditions that can present as itching in the scalp.

Medicated shampoos

How often you need to use medicated shampoos will depend on how severe your dandruff is and what treatment you are using. Always read the directions on the shampoo pack before using it. Some products are mild enough to be used every day, while others should only be used once a week. Over time, you will work out how often to use the shampoo to keep your dandruff under control.

Typically, those with a scaly scalp should be shampooing everyday. Infrequent shampooing may result in scale build-up and thus make symptoms worse. Most antidandruff shampoos are now rinse on-rinse off.

A conditioner may be used to prevent excessive drying from frequent washing. Matching antidandruff conditioners increase the effect of the shampoo by five to 10 per cent while unmatched conditioners may inactivate the shampoo. In general, it takes five to 10 washes to clear up dandruff.