Scalp allergies are caused by contact with allergens in the air or by substances actually touched and the reactions can be anything from a mild rash to serious inflammation, itching and patchy, temporary, hair loss.  The most common sources of allergies of the scalp are hair dyes and permanent solutions.  Reactions to allergens are usually swift, so there is little doubt about what is the cause of the burning or itching sensation they cause.  However, sometimes the reaction is delayed, so the origin is harder to track.

Skin allergies can, of course, occur anywhere on the body.  Sometimes the source of the allergic reaction is difficult to pin down, so a process of elimination is necessary.  The causes of skin allergies are many: metals, such as nickel, fragrances in perfumes, cosmetics, medications, preservatives and household products, latex (rubber), bath powders, tape and poisonous plants, such as poison ivy. 

The effects of severe scalp allergies can be particularly troublesome because of the presence of hair over the lesions that must be cut to properly treat the scalp or where the hair actually breaks off at the base, leaving bald spots.  Most people are somewhat self-conscious about the appearance of their hair.  A simple treatment that brings relief for any case of dermatitis is to bathe with a mild soap in cool to lukewarm water to relieve the itch.

Symptoms

Chemicals in dyes, tints, bleaches, straighteners and permanent waves as well as in soaps, shampoos and perfumes may irritate the skin, causing contact dermatitis, or an allergic reaction. 

The most common symptom of dermatitis or scalp allergies is the appearance of red, itchy raised areas on the skin called hives that can be very small dots or large ones.  Acute hives arise quickly and can last up to six weeks.  Sometimes they appear in groups that fade as other groups develop.  Hives near the eyes, lips or genitals swell a great deal and can be alarming, but usually go away in twenty-four hours.  The most common causes of acute hives are: foods, medicines, insect bites, sunlight, etc.  Chronic hives are much less common.  They may linger as long as six weeks and the cause may remain unknown.

Contact dermatitis is a common cause of rash and scalp itch.  It can be either an allergic or irritant condition.  The cause may be a new shampoo, soap, hair dye or hair product - particularly if it contains alcohol.

Scalp Infections

Infection can develop after an injury or wound to the skin, a bite or sting, a tattoo or piercing or other skin problem.  Symptoms of infection may include:

Increased pain, swelling, redness, or warmth around the affected area. Red streaks extending from the affected area. Drainage of pus from the area.  Swollen lymph nodes in the neck. Fever.

Although many scalp infections get better by themselves, treatment with medications may be needed.  Scratching an itchy scalp can lead to skin irritation or infection.  Examples of infections that may affect the scalp include:
Infection of the hair shafts (folliculitis), which begins as a red, tender area at or near the base of one or more strands of hair.  Folliculitis may look like small red pimples with a hair in the centre of each one.  The pimples may have pus in them and they often itch or burn.  

A bacterial skin infection, such as impetigo or cellulitis. Other causes of itchy scalp:

Seborrheic Dermatitis

This is also called dandruff in adults and cradle cap in infants.  Seborrheic dermatitis often leads to a dry scalp itch.  The cause of both dandruff and cradle cap is simply excess scale produced by the skin.  Dandruff is most prevalent in adolescents and gets worse in early adulthood.  Cradle cap is most common in the first three months of life and many babies are affected at one time or other.  Carefully drying the scalp well, moisturizing and limiting the use of soaps can help prevent recurrence.

Psoriasis

Psoriasis is a common skin condition that can cause a red rash on the scalp.  Usually the skin becomes thickened with a silvery scaling.  Scalp itch can sometimes occur, but it is not usually a feature. 

Head lice 

The head louse is a very common cause of scalp itch in children as it spreads with close contact.  Usually the resulting itch is behind the ears and at the back of the head where lice prefer to live.  Symptoms include scalp itch, visible white coloured lice and possibly red bite marks.  It’s also important to wash bedsheets and clothes as the lice can survive a few days without human contact.

Scalp itch and stress

It has been said stress can go to your head.  Work, family, money issues, weather and even our diets can put pressure on our scalp and cause us to scratch.  Lifestyle changes, rather than lotions and medications may be required here.

Some of the causes of dry, itchy scalp:
Improper rinsing of your hair.  Residue of chemical ingredients from shampoos and conditioners may have remained on your scalp.  Some scented shampoos could cause allergic reactions that lead to head or scalp itching.

A very itchy scalp may be a symptom of being in the menopausal stage.
Inappropriate use of hair relaxing and colouring products.

Poor nutrition.  Proper food intake and incorporating fruits and vegetables in your daily diet is a must.  Nuts and cereals are also good for the health.  The intake of starchy, protein-rich and fatty foods should be avoided. Anxiety, stress from work and too much thinking or worrying can cause flaking which leads to a dry and itchy scalp. Food allergies, excessive perspiration, exposure to dust and changing weather conditions are other factors which may contribute to a dry, itchy and sore scalp.  Food allergies can cause scalp eczema.

The author is a Consulting Dermatologist and can be contacted on 23131257 or by E-mail:               vandanjp@hotmail.com