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Understanding scalp and hair conditions as well as the fundamental hair structure is essential for proper hair care, diagnosis of common concerns, and effective treatment approaches.
Below, each major condition and structural component is addressed in detail based on current clinical understanding, incorporating scientific insight and practical guidance.
Dandruff (Seborrheic Dermatitis)
Dandruff commonly refers to flaking and itching of the scalp and is a manifestation of seborrheic dermatitis when localized to the scalp. It is characterized by white or yellow, sometimes greasy, flakes that shed easily and may be accompanied by itching and areas of redness or mild irritation. The underlying cause is multifactorial, often involving overgrowth of Malassezia yeast, increased production of sebaceous oil, genetic susceptibility, and environmental factors such as cold weather or stress. Though unsightly, dandruff is generally harmless and not contagious. Treatments include medicated shampoos with ingredients like zinc pyrithione, ketoconazole, selenium sulfide, or coal tar. Maintenance is essential as dandruff is often chronic with periodic flare-ups.
Psoriasis of the Scalp
Psoriasis of the scalp is a chronic, relapsing autoimmune disorder manifesting as well-demarcated plaques with silvery-white or gray scales over areas of erythema. Intense itching, burning, or soreness can be present, and the scales are typically thicker and more persistent than dandruff. While the primary cause is an abnormal, overactive immune response triggering expedited skin turnover, it is also influenced by genetic factors and environmental triggers such as stress, infections, and cold weather. Psoriasis is non-contagious but may overlap with seborrheic dermatitis, requiring careful clinical differentiation. Treatment may include topical corticosteroids, vitamin D analogs, coal tar, salicylic acid, phototherapy, or systemic immunomodulators for severe cases.
Alopecia Areata
Alopecia areata is an autoimmune disorder where the immune system targets hair follicles, resulting in smooth, round, non-scarring patches of hair loss. It can affect the scalp, beard, eyebrows, and body hair, and may be accompanied by nail abnormalities or the presence of “exclamation point” hairs (short broken hairs tapering at the base). While the cause is not always clear, genetic predisposition and triggers such as illness or stress are implicated. The course is unpredictable, with spontaneous regrowth possible but also risk of recurrence or chronicity.
Androgenetic Alopecia (Male/Female Pattern Baldness)
Androgenetic alopecia is the most prevalent form of hair loss in adults, marked by progressive thinning in distinct patterns. In men, it presents as a receding frontal hairline and vertex thinning, often progressing to a “M” shape or “Hippocratic wreath,” while in women, diffuse thinning around the crown and part line is most typical. Androgens, especially dihydrotestosterone (DHT), act on genetically susceptible hair follicles, shortening the growth cycle and yielding progressively finer hairs. The condition is chronic and hereditary, with various genetic and hormonal influences. Treatments include minoxidil, finasteride (for men), anti-androgen and hair transplantation, depending on patient preference and severity.
Telogen Effluvium
Telogen effluvium is a temporary, diffuse shedding of hair that usually occurs 2–3 months after a physical or emotional trigger such as severe illness, surgery, childbirth, or significant psychological stress. It is characterized by increased daily shedding and generalized thinning rather than patchy loss. Because follicles are prematurely shifted into the resting (telogen) phase, hair loss is usually reversible, with regrowth seen after the trigger is resolved or the body
Trichotillomania
Trichotillomania, or hair-pulling disorder, is a compulsive behavior resulting in patchy, often geometric hair loss following repeated pulling, most frequently from the scalp, eyebrows, or eyelashes.
The etiology is multifactorial, involving genetic, psychological, and neurobiological factors, and is often associated with tension-release or gratification after pulling. Trichotillomania may overlap with anxiety, mood, or obsessive-compulsive disorders and leads to significant psychosocial distress.
Folliculitis
Folliculitis refers to the inflammation or infection of hair follicles, presenting as small, erythematous, sometimes pus-filled papules or pustules that often cluster on the scalp. The most common etiology is bacterial infection (especially Staphylococcus aureus), but fungi, viruses, or physical irritation can also be responsible. Complications include pain, tenderness, crusting, and possible patchy hair loss, with risk of deeper infection if left untreated. Management may require topical or systemic antimicrobials and addressing underlying causes.
Scalp Eczema
Scalp eczema encompasses several types, most notably atopic dermatitis and seborrheic dermatitis, displaying symptoms of redness, persistent itching, dry or scaly skin, and sometimes weeping or crusting lesions. Triggers may include genetic factors, irritants, allergens, or microbial imbalance. Chronicity and seasonal flares are common, and management includes topical corticosteroids, calcineurin inhibitors, and regular moisturizing.
Seborrhea
Seborrhea is a descriptive term for increased sebaceous (oil) gland activity, and often refers to seborrheic dermatitis when associated with inflammation and scaling. Causes include hormonal changes, genetic predisposition, stress, and especially overgrowth of Malassezia yeast on the scalp, leading to characteristic greasy, flaky patches. Itching is typical, and the condition responds to antifungal and anti-inflammatory treatments.
DRY SCALP
Dry scalp manifests as small, white, dry flakes, tightness, and pruritus, and can be differentiated from dandruff by the former’s lack of oiliness and less pronounced redness. Causes include environmental factors (cold, dry air), excessive washing or harsh hair products, and insufficient sebum production. Treatment targets gentle cleansing, scalp hydration, and reduction of irritant exposure.
Oily Scalp
An oily scalp involves excessive sebum production, resulting in greasy or limp hair, visible shine at the roots, and sometimes larger, sticky flakes or concurrent scalp conditions such as seborrheic dermatitis. Causes are multifactorial, involving genetics, hormonal fluctuations, stress, overwashing, use of inappropriate hair products, and certain medical conditions. While some oiliness is healthy, excess can clog follicles and foster inflammatory conditions. Treatment involves correct washing frequency, suitable shampoos, and dietary and lifestyle management.
Lice (Pediculosis)
Head lice (pediculosis capitis) are parasitic insects that infest the scalp and hair shafts, feeding on human blood. Key symptoms include persistent scalp itching (pruritus), tickling sensation, visible lice or nits (eggs) tightly attached near the scalp, and in severe cases, secondary infection due to scratching. Lice spread through direct head-to-head contact and are not an indicator of poor hygiene. Treatment relies on topical pediculicides and fine-tooth combing.
Scalp Acne
Scalp acne is an inflammation of the hair follicles that presents as pimples, whiteheads, pustules or even cysts on the scalp or hairline. Causes include blockage of follicles by sebum, bacteria (such as Cutibacterium acnes), dead skin cells, or reactions to hair products. Management includes antiseptic shampoos, topical antibiotics, and elimination of exacerbating irritants.
Follicular Keratosis
Follicular keratosis, often termed keratosis pilaris when affecting other areas, is characterized by tiny, rough, keratotic papules clustered around hair follicles. Rare forms such as keratosis follicularis spinulosa decalvans seen on the scalp are associated with scarring alopecia and follicular papules. Symptoms often include dry skin, rough texture, and occasionally scarring or hair loss in the alopecia-associated variants.
Hyperpigmentation of the Scalp
Scalp hyperpigmentation appears as darkened patches or spots, and may be due to post-inflammatory changes (such as from eczema, lichen planus pigmentosus), drug reactions, sun exposure, or trauma. It is more prevalent in individuals with darker skin tones and can be persistent or progressive. Clinical management focuses on addressing the cause, sun protection, and topical depigmenting agents if desired.
