Yes, the hair is indeed our crowning glory. But not when we are often scratching and having a persistently itchy scalp. This article aims to tackle such a problem, what can cause this itchiness, and how one can deal with it.
The scalp actually has 5 distinct anatomic layers: the skin, close connective tissue with its cutaneous nerves and vessels, epicranial aponeurosis, loose connective tissue, and the pericranium. [1, 2, 3]
An illustration showing the layers of the scalp.
Being thick, the skin is the layer from which the scalp hair grows. It is abundant in blood vessels and sebaceous glands.
2. Close Connective Tissue
It consists of layers of fat and fibers, lying underneath the skin. Sometimes called superficial fascia, this layer provides a passageway for nerves and blood vessels.
3. Epicranial aponeurosis
As a layer of tendons, this provides insertions for the occipitofrontalis muscles. It also allows fluid and blood to pass from the scalp to the upper eyelids.
4. Loose Connective Tissue
This layer separates the upper three layers from the pericranium. Emissary blood vessels also navigate through this layer, linking the diploic veins and intracranial venous sinuses to the scalp veins.
Considered as the cranial bones’ periosteum, this layer provides nourishment to the bone and the ability to repair.
Within these layers exist cells, collagen and elastic fibers, blood vessels, sweat glands, oil glands, adipose and muscles. These all work together to perform the scalp’s functions, which is to enable breathing of the skin, exocrine secretions, temperature regulation, control of water loss, and protection against bacteria and other microorganisms. Any abnormality of these structures can produce deviations from the skin’s normal functions and thus cause symptoms such as scalp itching. 
What Causes Itching of the Scalp?
A pruritic scalp is usually brought about by either infection, lack of moisture, inflammation, or even anxiety. The more common roots of itching include the following:
Parasitic Infection: Head Lice
Pediculosis capitis, more commonly known as head lice, are one of the most common reasons for an itchy scalp. These parasites are usually 2-3 millimeters in length, swarming the head, and affixing their eggs at the foot of the hair shaft. These usually cause severe itching of the scalp and are usually transmitted by direct person to person contact. [ 5, 6]
A female head louse places its ova on the hair, attaching them to the shafts. A week after, these lice hatch and the nits remain, growing more obviously as the hair lengthens. These lice nourish themselves by feeding on the host’s blood. After 6 to 10 days, they mature in to adults, capable of crawling from one host to another. Hence, further pruritus prevails, provoking one’s need to scratch. 
An image showing an adult head louse, causing an itchy scalp.
A photo of a patient with visible nits on the hair shafts.
This is usually caused by skin or scalp contact to chemicals such as dyes, shampoos, conditioners and other cosmetics. These substances may either cause skin irritation or allergic reactions. They are usually presented as skin itching, causing erythematous lesions from relentless scratching. Succeeding use of the irritant can induce crusting, scaling and more profuse itching of the scalp. Thus, recognition of the allergen or irritant substance, and its avoidance must be done. [5, 8]
A subject with an itchy scalp due to contact dermatitis from use of a new shampoo.
A fungal infection brought about by Malassezia furfur, this is a common scalp condition, mostly occurring after the adolescent stage of childhood. The infected person constantly scratches his scalp, which sheds off whitish silver scales. [5, 8, 9]
If affected with dandruff, the cell turnover of the scalp is faster than normal. Skin cells of the scalp mature and are discarded every 2 to 7 days. This results in large, oily, dead skin cells in clumps, what we usually see as dandruff. [9, 10]
This is often influenced by sebum or sebaceous secretions, metabolic derivatives of skin inhabitants such as Malasezzia, and one’s susceptibility. [11, 12, 13]
An image showing fungal infection of the scalp, or dandruff.
Psoariasis is an autoimmune illness producing erythematous, elevated, scaly skin lesions, usually at the scalp, knees and elbows. The skin may appear thickened and pruritic, but may bleed when their scales are rubbed off. 
In this illness, an inflammation of the skin is triggered by the immune system, enabling a more rapid skin cell turnover as fast as 3 to 4 days. The upsurge of old cells being substituted by the new ones produces the silver scales, as seen in psoriasis. [15, 16]
An image depicting psoriasis of the scalp, with its characteristic silvery white scales.
Source : www.noskindiseases.com
Ringworm of the Scalp
Scalp ringworm infection is brought about by the fungus Tinea capitis. Usually affecting the hair shaft and the scalp, the illness is contagious, particularly among toddlers and preschool children. 
Aside from scalp itching, hair loss and a scaly skin lesion may also be present. If severe, a swollen mass with pus discharge may be visible on the scalp, which may be a bit tender. 
Scalp infected with Tinea capitis, having ringworm infection of the scalp.
Also known as Proprionibacterium foliculitis and acne necrotica miliaris, scalp folliculitis are characterized by inflamed hair follicles of the scalp. It is usually brought about by the bacteria Propionibacterium and Staphylococcus, the fungal Malassezia, and mites Demodex. It is commonly presented as small, pruritic pustules on the scalp. When scratched, they can become uncomfortable and crusted. [19, 20]
An image showing scalp folliculitis, with inflamed hair follicles at the scalp.
This is a condition in which one experiences pruritus even without any physical stimuli, except anxiety. Studies have been made showing that skin sensitivity and stress reactions may further aggravate anxiety and induce itchiness of the scalp. [21, 22]
It often produces a cycle of repeated itch–scratch-itch episodes. This causes hyperpigmentation and production of scars. It is also thought to be influenced by nerve stimulation, which eventually lead to irritation of the skin. 
How to Deal With An Itchy Scalp: The Treatment Options
Treatment of scalp itching is based on the root and origin of the pruritus. [5, 8, 16]
Pediculosis capitis, or head lice, are usually treated with medications such as Permethrin, Malathion and Benzyl alcohol lotions and shampoos. These agents eradicate either the lice, the nits, or both. They are usually done repeatedly for 7 to 9 days for more complete and thorough treatment results.
The main treatment for contact dermatitis is still prevention and avoidance in using the irritant causing the allergic reaction to the scalp. Application of a topical corticosteroid can also be done as management.
Dandruff can be treated using shampoos with zinc pyrithione, ketoconazole and selenium sulfide as components. These agents do not only eliminate fungi, but also control skin cell production. If severe infections are at hand, steroids like betamethasone can also be prescribed.
In managing psoriasis, medicated shampoos and creams with tazarotene, coal tar, salicylic acid and calcipotriene can be utilized. Oral medications may also be of use, particularly the retinoids, steroids, methotrexate, cyclosporine and monoclonal antibodies.
Tinea capitis infections, or ringworms, can be treated using antifungals like ketoconazole, itraconazole, terbinafine, fluconazole and griseofulvin. They may be given as shampoos or taken orally.
Folliculitis of the scalp usually resolve spontaneously after 2 weeks. However, if persistent, Burow’s solution or medicated shampoos may be used.
Antihistamines and anti anxiolytics can be used to manage neurodermatitis. This does not only control itching, but can alleviate anxiety attacks as well. Thus, preventing further itching and stopping the itch-scratch- itch cycle.
Preventing Itchy Scalp
In preventing itching of the scalp, one must be reminded of the following: 
- Brush the hair 2 to 3 times daily to disseminate natural oil
- Change your hair product every two weeks to remove any build up caused by the previously used shampoos and conditioners.
- Use a conditioner to add shine, and invigorate nutrients and fibers
- Avoid products containing alcohol, to prevent further drying of the hair and scalp
- Dry the hair thoroughly
- Try to check for the presence head lice occasionally
- Avoid too much sun exposure to prevent drying of hair and scalp, and thus eliminate itching as well.
- Avoid too much stress
- Try to consume 8 to 10 glasses of water per day
- Vitamin E supplementation advised
- Consult a physician if such symptoms are noticed
- De Angelis, Y, et al. Three Etiologic Facets of Dandruff and Seborrheic Dermatitis; Malassezia fungi, Sebaceous Lipids, and Individual Sensitivity. Journal of Investigative Dermatology Symposium Proceedings. 2005; 10 (3): 295-7.
- Ro, B, et al. The Role of Sebaceous Gland Activity and Scalp Microfloral Metabolism in the Etiology of Seborrheic Dermatitis and Dandruff. Journal of Investigative Dermatology Symposium Proceedings. 2005.; 10 (3): 194-7.
- Gemmer, C, et al. Fast, Noninvasive Method For Molecular Detection and Differentiation of Malassezia yeast Species on Human Skin and Application of the Method to Dandruff Microbiology. Journal of Clinical Microbiology. 2002; 10 (9): 3350-7.
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