How does a head infested with lice look?

Understanding Head Lice Infestation

The Life Cycle of a Head Louse

«Nits»: The Eggs

Nits are the eggs laid by head‑lice. They appear as tiny, oval structures measuring about 0.8 mm in length. The shell is hard, translucent at first, becoming opaque and yellow‑brown as the embryo develops.

Nits attach firmly to the hair shaft within a millimetre of the scalp. The attachment is made with a cement‑like substance that resists removal by combing. Because the scalp provides warmth, the eggs hatch in 7–10 days, releasing mobile lice.

Key visual clues for identifying nits:

Position: fixed to the hair close to the scalp, not easily moved.
Shape: oval, slightly flattened, resembling a miniature grain of rice.
Color progression: clear → white → yellow‑brown → dark brown as the embryo matures.
Side of hair: most commonly found on the underside of strands, where temperature and humidity are optimal.

The presence of numerous nits, especially when aligned in rows along the hair, indicates an active infestation. Careful inspection under bright light or magnification reveals the characteristic cemented attachment, distinguishing nits from dandruff or hair debris.

«Nymphs»: The Young Lice

The presence of lice nymphs on a scalp produces a distinct visual pattern. Nymphs are the immature stage of Pediculus humanus capitis and differ from adult lice in size, coloration, and mobility.

Nymphs measure approximately 1 mm in length, about half the size of mature specimens. Their bodies appear translucent to light brown, allowing the underlying hair shaft to be partially visible. Because they have not yet developed the fully pigmented exoskeleton of adults, they often blend with the hair, creating a subtle, mottled appearance rather than the obvious dark specks associated with adult lice.

Key visual indicators of a nymph‑rich infestation include:

Fine, pale specks clinging to hair shafts, especially near the scalp where temperature is highest.
Increased movement of tiny insects when the head is disturbed; nymphs react quickly, scattering along strands before settling.
Presence of tiny, oval-shaped eggs (nits) attached close to the scalp, often overlapped by clusters of nymphs during active feeding.

Nymphs feed on blood several times a day, causing mild irritation that can lead to scratching. Continuous scratching may produce redness and small abrasions, further emphasizing the infestation’s appearance.

Recognizing the characteristic pale specks and heightened activity of these young lice enables early detection, which is essential for effective treatment before the population matures into a larger, more conspicuous adult cohort.

«Adult Lice»: The Matured Parasites

Adult lice are the reproductive stage of the head‑lice life cycle. They measure 2‑3 mm in length, have a flattened, elongated body, six legs with clawed tarsi, and a light‑brown to grayish coloration. Antennae are short, and the head bears a pair of compound eyes. Eggs hatch within 7‑10 days, allowing the adult population to expand rapidly when conditions are favorable.

A scalp heavily populated with adult lice exhibits several observable characteristics. Live insects move quickly across hair shafts, especially near the hairline and behind the ears. Their presence produces a persistent, irritating sensation that often leads to frequent scratching. The skin may appear reddened, with small puncture marks where the insects feed. Additionally, nits—oval, cemented eggs—are visible attached to the base of each hair strand, forming a dense, white‑to‑yellowish line close to the scalp.

Key visual indicators of an adult‑lice infestation:

Mobile, grayish insects observable on hair shafts and scalp surface.
Concentrated clusters of nits within 1 mm of the hair root.
Red, inflamed patches of skin with occasional tiny hemorrhagic spots.
Crusty or scaly debris resulting from repeated scratching.

The combination of active insects, cemented nits, and irritated scalp tissue defines the typical appearance of a head heavily infested with mature lice.

Visual Signs of Head Lice

«The Presence of Nits»

«Location of Nits on Hair Shafts»

Nits attach firmly to the hair shaft using a cement‑like secretion, positioning themselves where the shaft is most secure. The majority of nits are found within a few millimetres of the scalp, where the hair is thickest and temperature supports egg development. Additional concentrations appear in areas where hair density is high and the scalp is less exposed to movement.

Base of the shaft, directly adjacent to the scalp, especially on the occipital region and nape of the neck.
Behind the ears, where hair forms a natural pocket.
Along the crown, particularly on the lower half of the shaft where hair tends to be longer.
Near the hairline, especially on the frontal scalp where hair is finer but still offers a secure attachment point.

Nits differ from dandruff or debris by their firm attachment; a gentle pull on the hair often reveals a translucent, oval structure firmly glued to the shaft. The eggs are typically oriented with the operculum (cap) facing outward, aligning with the direction of hair growth.

Effective inspection requires a fine‑toothed comb held at a 45° angle to the scalp, moving from root to tip in short strokes. Visual examination under bright light or a magnifying lens enhances detection of the characteristic oval shape and the brownish‑yellow colour of mature nits.

«Distinguishing Nits from Dandruff or Hair Casts»

The visual assessment of a scalp suspected of lice infestation relies on accurate identification of the tiny eggs, known as nits, and their distinction from common debris such as dandruff and hair casts.

Nits adhere firmly to the hair shaft, typically within ¼ inch of the scalp where temperature favors development. They appear as oval, cream‑to‑brown bodies about 0.8 mm long, with a smooth, glossy surface. The attachment point is a solid, pin‑like structure that resists removal by gentle combing or brushing.

Dandruff consists of loose, white or yellowish flakes composed of dead skin cells. Flakes detach easily, float in the hair, and lack any anchoring mechanism. Their irregular shape and crumbly texture differentiate them from the compact, immobile form of nits.

Hair casts are tubular, translucent sleeves that encircle the hair shaft. Unlike nits, casts slide freely up and down the hair when manipulated, often extending several millimetres in length. Their colour matches the hair, and they can be removed as a single sleeve without tearing the shaft.

Key visual criteria for differentiation:

Attachment: nits are glued to the shaft; dandruff and casts are not.
Location: nits cluster near the scalp; dandruff distributes along the entire hair length; casts appear at any point but move freely.
Shape and size: nits are oval and ≤ 1 mm; dandruff flakes are irregular and larger; casts are cylindrical and longer than 1 mm.
Removal test: gentle combing dislodges dandruff and casts, while nits remain fixed.

Applying these observations enables reliable identification of lice presence and prevents misinterpretation of harmless scalp debris. The focus of the analysis remains «Distinguishing Nits from Dandruff or Hair Casts».

«Visible Lice on the Scalp and Hair»

«Color and Size of Adult Lice»

Adult head lice (Pediculus humanus capitis) are generally pale‑gray to light brown. The exoskeleton contains a thin, translucent cuticle that often appears whitish when the insect is alive, becoming darker after death. Pigmentation is minimal; the body lacks distinct markings, making the overall hue uniform across individuals.

The body length of a mature louse ranges from 2.3 mm to 3.5 mm, with a width of approximately 0.8 mm. The head, slightly broader than the thorax, measures about 0.4 mm. These dimensions place adult lice among the smallest ectoparasites capable of navigating human hair shafts.

Key measurements:

Length: 2.3 mm – 3.5 mm
Width: ≈ 0.8 mm
Head width: ≈ 0.4 mm

Color and size together facilitate identification of live lice during visual inspection of a scalp. The combination of a pale‑gray to light‑brown hue and a body no longer than 3.5 mm distinguishes adult specimens from nymphal stages, which are noticeably smaller and lighter in color.

«Movement and Hiding Spots of Lice»

Lice navigate a host’s hair by grasping individual strands with their clawed legs and moving in a rapid, jerky fashion. Their locomotion averages 0.5 mm per second, enabling swift transitions between adjacent shafts. Movement is primarily horizontal; occasional vertical climbs occur when searching for feeding sites near the scalp surface.

Typical hiding locations include:

The space between the scalp and the hair shaft, where temperature and humidity remain stable.
The base of hair follicles, especially in the nape and behind the ears, providing protection from mechanical disturbance.
The outer layer of the hair cuticle, where lice attach their eggs (nits) to secure future development.
The region under dense hair clusters, such as the crown, which limits visual detection.

Visible indicators of infestation arise from the concentration of lice in these zones: increased scalp irritation, presence of live insects, and clusters of firmly attached nits. The combination of rapid, strand‑to‑strand movement and strategic concealment makes detection challenging without close examination.

«Skin Reactions and Irritation»

«Redness and Bumps from Bites»

Redness and bumps caused by lice bites appear as localized inflammation on the scalp. The affected skin often turns pink to reddish‑brown, with a slightly swollen appearance that may spread across the crown, behind the ears, and along the hairline. The irritation is usually confined to areas where nits are attached, reflecting the feeding sites of the insects.

Bumps manifest as small, raised papules ranging from 1 to 3 mm in diameter. They are firm to the touch and may develop a central punctum where the louse injected saliva. The lesions are typically grouped in clusters, corresponding to the distribution of adult lice and nymphs.

Key visual indicators include:

Pink‑to‑red patches of irritated skin.
Discrete papules or pustules, often in clusters.
Presence of visible nits or adult lice near the lesions.
Occasional itching that intensifies after prolonged exposure.

Distinguishing features from other scalp disorders:

Redness is limited to the immediate vicinity of lice activity, unlike the diffuse erythema seen in seborrheic dermatitis.
Bumps lack the greasy scales characteristic of psoriasis and do not present the crusted lesions typical of impetigo.
The combination of localized inflammation and visible lice or nits confirms the diagnosis.

«Scratch Marks and Sores»

A lice‑infested scalp often shows visible nits attached to hair shafts, live insects moving among strands, and secondary skin changes caused by persistent scratching.

Scratch marks appear as linear or irregular abrasions where the scalp has been repeatedly rubbed or clawed. The lesions are typically shallow, with fresh edges that may be pink or slightly reddish. In areas of frequent contact, the skin may become thickened and hyperkeratotic, giving the marks a rough texture.

Sores develop when scratching breaches the epidermal barrier. Early lesions present as small, erythematous papules that can coalesce into larger, inflamed patches. If bacterial colonisation occurs, the sores may exude serous fluid, develop a yellowish crust, or show localized swelling. Chronic irritation can lead to hyperpigmented scars that persist after the infestation resolves.

Management requires a two‑fold approach. First, eradicate the lice with an appropriate pediculicide or manual removal of nits. Second, treat the cutaneous damage: cleanse lesions with mild antiseptic solution, apply topical antibiotics if infection is suspected, and use soothing agents such as calamine lotion or low‑potency corticosteroid creams to reduce inflammation and prevent further scratching. Monitoring for signs of secondary infection—increased pain, purulent discharge, or expanding erythema—ensures timely intervention.

«Secondary Infections Due to Scratching»

A head crowded with lice typically shows visible adult insects, translucent nits attached to hair shafts, and a reddened scalp irritated by constant movement. Persistent irritation provokes scratching, which disrupts the epidermal barrier and creates entry points for opportunistic microbes.

«Secondary Infections Due to Scratching» arise when bacteria colonize these micro‑abrasions. The most frequent agents include Staphylococcus aureus, Streptococcus pyogenes, and occasional Gram‑negative organisms. Infection manifests as localized swelling, purulent discharge, crust formation, and increased pain beyond the baseline pruritus.

Common clinical indicators:

Warm, tender nodules at scratch sites
Yellowish or bloody crusts
Rapid enlargement of erythema
Foul odor from exudate

Effective management combines removal of lice and nits, rigorous scalp cleansing, and targeted antimicrobial therapy. Topical or oral antibiotics address bacterial proliferation, while anti‑itch preparations limit further trauma. Prompt treatment prevents spread to adjacent skin and reduces risk of systemic complications.

Symptomatic Indicators of Head Lice

«Intense Itching of the Scalp»

«Mechanism of Itching Sensation»

A head populated by pediculus humanus capitis reveals several visual cues: numerous tiny, grayish insects moving along hair shafts, ovoid nits attached near the scalp, and localized erythema where insects feed. The itching sensation originates from a defined neurophysiological cascade.

Lice insert their mouthparts into the epidermis to ingest blood. Saliva containing anticoagulant proteins is deposited during each bite.
Salivary proteins act as allergens, binding to receptors on cutaneous mast cells.
Mast cells degranulate, releasing histamine and other inflammatory mediators.
Histamine stimulates peripheral C‑fibers and Aδ‑fibers, transmitting pruritic signals to the dorsal horn of the spinal cord.
Central processing in the somatosensory cortex registers the sensation as itch, prompting scratching behavior.

Repeated scratching exacerbates epidermal damage, increasing erythema and producing secondary crusted lesions. The combination of visible parasites, nits, and inflammatory changes provides a clear external representation of the underlying pruritic mechanism.

«Areas Most Affected by Itching»

A lice‑infested scalp typically exhibits clusters of live insects and nits attached to hair shafts, accompanied by localized redness and irritation. Itching concentrates in regions where lice feed and lay eggs, creating the most noticeable discomfort.

Crown and vertex, where hair density is greatest and lice congregate for optimal temperature.
Nape of the neck, a sheltered area that retains moisture and warmth.
Behind the ears, a protected zone with limited airflow.
Temples, especially the lateral edges where hair meets skin.

These zones experience heightened itching because they provide stable microclimates, abundant blood supply, and reduced exposure to sunlight, all of which favor lice activity and egg deposition. The resulting sensory response stems from mechanical irritation by the insects’ mouthparts and allergic reactions to their saliva.

«Sensation of Something Moving on the Scalp»

The feeling of a subtle, continuous motion across the scalp signals the presence of mobile ectoparasites. The movement is often described as a light tickling or crawling sensation that intensifies when the head is still and diminishes with vigorous shaking.

Typical characteristics include:

Intermittent tingling that appears without external stimulus.
Sensation localized to the hairline, temples, or behind the ears.
Increased awareness during periods of rest or after sleep.
Slight discomfort that escalates when hair is brushed or combed.

Visible indicators accompanying the sensation are:

Small, translucent insects clinging to hair shafts.
Tiny, white or brown oval eggs (nits) attached close to the scalp.
Redness or mild irritation of the skin where insects bite.

The described perception may be confused with:

Itching caused by dry scalp.
Sensory anomalies from neurological conditions.

Accurate identification relies on correlating the moving‑scalp feeling with the presence of live parasites and their eggs. Prompt inspection and appropriate treatment eliminate both the physical discomfort and the underlying infestation.

«Difficulty Sleeping Due to Discomfort»

A head occupied by head‑lice displays several unmistakable visual cues. Live insects move among strands, often visible as tiny, grayish specks. Nits appear as oval, whitish or yellowish shells glued firmly to hair shafts, typically within a centimeter of the scalp. The scalp may show reddened patches, small sores, or flaking skin resulting from repeated scratching.

These physical manifestations generate persistent irritation. Itching intensifies during periods of inactivity, especially at night, when reduced external distractions amplify sensory perception. Continuous micro‑trauma to the scalp disrupts the ability to maintain a relaxed state, causing frequent awakenings and difficulty achieving deep sleep phases.

Typical indicators of sleep disturbance related to lice‑induced discomfort include:

Repeated nocturnal arousals caused by intense itching.
Prolonged periods of tossing and turning in an effort to alleviate scalp sensations.
Reduced total sleep time measured by objective monitoring or self‑report.
Increased daytime fatigue and diminished cognitive performance directly linked to fragmented rest.

Addressing the infestation promptly eliminates the source of irritation, restores scalp condition, and consequently improves the capacity for uninterrupted sleep.

«Swollen Lymph Nodes»

Lice infestation on the scalp produces visible indicators such as live insects, translucent eggs adhered to hair shafts, and frequent scratching that may cause erythema. Additional signs include small dark specks resembling pepper grains, which are nits attached near the scalp, and a gritty sensation when combing.

Swollen lymph nodes often accompany severe infestations because the immune system reacts to prolonged irritation and secondary bacterial infection. The cervical region, particularly the posterior and anterior chains, is most commonly affected.

Typical features of lymph node enlargement include:

Size exceeding 1 cm in short axis, though larger dimensions may occur in children;
Firm but mobile consistency, distinct from the fixed hardness of malignant masses;
Tenderness when palpated, reflecting an acute inflammatory process;
Rapid onset within days of intense pruritus or skin breakdown.

Persistent enlargement beyond two weeks, lack of tenderness, or associated systemic symptoms such as fever, weight loss, or night sweats warrant further evaluation. Prompt antimicrobial therapy for secondary infection and thorough mechanical removal of lice reduce the inflammatory stimulus and facilitate lymph node resolution.

Areas to Inspect for Lice

«Behind the Ears»

The area «Behind the Ears» often reveals the most evident signs of a lice‑infested scalp. Small, oval, yellow‑white nits cling tightly to hair shafts, especially where hair is short and dense. The nits appear as immobile specks, sometimes mistaken for dandruff, but they do not flake away when brushed.

Visible indicators in this region include:

Redness or mild inflammation of the skin caused by frequent scratching.
Small puncture marks where lice have fed, leaving tiny, pale lesions.
Accumulation of adult lice, visible as rapid, darting insects measuring 2–4 mm.
Clusters of nits attached near the hair roots, often forming a line along the hair line.

These characteristics combine to create a distinctive visual profile: a mixture of live insects, attached eggs, and irritated skin, most pronounced in the protected, warm zone behind the ears.

«Near the Nape of the Neck»

A heavy lice presence produces a distinct visual pattern on the scalp, especially in the area «Near the Nape of the Neck». The hair at this junction often appears thinner because lice concentrate where hair is denser and easier to grasp. Small, grayish‑white eggs (nits) cling tightly to the shaft, positioned within a few millimeters of the scalp surface.

Visible signs in the «Near the Nape of the Neck» region include:

Numerous nits attached at the base of each hair strand, forming a line that resembles fine sand.
Live lice, 2–4 mm long, moving rapidly along hair shafts.
Redness or slight swelling of the skin caused by scratching.
Fine, whitish debris composed of dead lice and excrement, creating a dusty coating.

These indicators collectively confirm an infestation and aid in distinguishing it from other scalp conditions. Prompt removal of nits and treatment of live lice are essential to prevent spread to other hair zones.

«Along the Hairline»

The hairline of an infested scalp displays several unmistakable visual cues. Live lice, measuring 2–3 mm, may be seen moving along the border of the hair, especially where hair meets the forehead. Their bodies appear gray‑brown, translucent when viewed against light.

Typical signs along the hairline include:

Small, oval shells firmly attached to hair shafts within 1 cm of the scalp; these are nits, often white or yellowish.
Clusters of nits positioned at the base of hair strands, forming a line that follows the natural hair‑edge.
Redness or mild inflammation of the skin directly beneath the hairline, caused by frequent scratching.
Crusty debris resulting from dried blood or saliva, occasionally visible on the forehead or near the temples.

These indicators concentrate at the hairline because the area provides warmth, moisture, and easy access to the scalp, creating an optimal environment for both adult lice and their eggs. Prompt visual inspection of the hairline, combined with a fine‑toothed comb, allows accurate detection and effective treatment.

«Crown of the Head»

The crown of the head is the most common locus for visible signs of a lice infestation. Lice lay eggs (nits) close to the scalp, and the density of hair at the crown provides an ideal environment for attachment.

Typical indicators at the crown include:

Small, oval nits firmly glued to hair shafts, often appearing white or translucent;
Live lice, approximately 2–3 mm long, moving rapidly across the hair surface;
Localized redness or inflammation of the skin caused by frequent scratching;
Accumulation of a fine, grayish debris known as “lice dirt,” which consists of fecal matter and dead insects.

These features together form the characteristic appearance of a scalp affected by lice, with the crown region presenting the highest concentration of observable evidence.

Factors Affecting Visibility of Lice

«Hair Type and Color»

Lice infestations become visible through the interaction of the parasite with the host’s hair characteristics. Dense, curly hair traps nymphs and eggs, creating clusters that appear as small, moving specks against the dark background of the strands. Straight, fine hair offers less concealment; lice are more readily seen as isolated insects moving along the shaft.

Color influences contrast. Light‑colored hair highlights the dark bodies of adult lice and the whitish shells of nits, making them easier to detect. Dark hair reduces visual separation, requiring closer inspection to distinguish lice from the surrounding fibers. The combination of hair texture and shade determines the overall visual presentation of an infested scalp.

Typical observations include:

Curly, thick hair: dense aggregations, higher likelihood of unnoticed nits near the scalp.
Straight, thin hair: isolated insects, clearer movement patterns.
Blonde or light‑brown hair: pronounced contrast, visible dark insects.
Dark brown or black hair: muted contrast, reliance on tactile inspection or magnification.

«Severity of Infestation»

A lice‑infested scalp displays visual changes that correspond to the density of the parasite population. The amount of live lice, nits attached to hair shafts, and secondary irritation determine the perceived severity.

Mild infestation – few adult lice and scattered nits; hair appears normal, occasional small white specks near the roots; scalp may show slight redness.
Moderate infestation – dozens of lice and numerous nits; hair strands contain clusters of white oval shells; scalp exhibits noticeable redness, occasional scratching marks, and a faint greasy film.
Severe infestation – hundreds of lice, dense layers of nits covering most hair; hair looks dirty, tangled, and laden with white debris; scalp is intensely inflamed, with extensive scratching, crusted lesions, and possible secondary bacterial infection.

Increasing severity amplifies visual clutter, scalp irritation, and risk of complications. Early identification of these signs enables prompt treatment and prevents progression to the severe stage.

«Lighting Conditions During Inspection»

Effective visual assessment of a scalp infested with lice depends heavily on the quality of illumination used during inspection. Poor lighting obscures nits adhered to hair shafts and hampers differentiation between live insects and debris, leading to inaccurate diagnosis.

Optimal lighting conditions include:

Bright, uniform illumination of at least 1 000 lux to reveal translucent nits attached near the scalp.
Neutral white light with a color temperature between 4 500 K and 5 500 K, minimizing color distortion and enhancing contrast.
Direct, frontal light positioned at a 45‑degree angle to the scalp, reducing shadows that can conceal nits in hair folds.
Adjustable focus, allowing close‑up inspection of the hairline, behind ears, and the nape of the neck where infestations commonly concentrate.

Practical implementation:

Use a portable LED inspection lamp equipped with a diffuser to achieve even light distribution.
Combine the lamp with a magnifying loupe (≥ 3× magnification) to increase visual resolution.
Verify illumination intensity with a lux meter before beginning the examination.
Re‑evaluate lighting after repositioning the subject’s head to maintain consistent exposure across all regions.

Consistent application of these lighting standards improves detection accuracy, facilitates timely treatment decisions, and reduces the likelihood of missed nits during visual inspection.

Differentiating Head Lice from Other Conditions

«Dandruff»

Dandruff manifests as fine, white to grayish flakes that detach easily from the scalp and settle on hair shafts and shoulders. The condition results from accelerated turnover of skin cells, often accompanied by mild irritation.

When a scalp hosts both dandruff and an infestation of lice, visual cues overlap. Lice create a dense, uneven appearance due to the presence of adult insects and their eggs, while dandruff adds a uniform layer of detached particles. The combination can give the impression of a heavily soiled head.

Key visual distinctions:

«Dandruff» flakes are loose, soft, and readily brush away; lice nits adhere firmly to hair strands, appearing as oval, cement‑filled capsules.
Adult lice are mobile, typically brown or gray, moving quickly across the scalp; dandruff does not exhibit movement.
Irritation from lice often produces localized redness and small sores; dandruff may cause mild itch without visible lesions.
The pattern of flake distribution is diffuse for dandruff, whereas lice eggs concentrate near the hairline, ears, and neck.

«Dry Scalp»

A head affected by lice often presents with a noticeably dry scalp. The condition «Dry Scalp» is characterized by reduced moisture, flaking skin, and a tight sensation. These features become more pronounced when lice feed on blood and irritate the skin, accelerating the loss of natural oils.

Typical visual indicators include:

Fine, white or yellowish flakes covering hair shafts and shoulders.
Red or pink patches where the scalp has been scratched.
Visible nits attached to hair strands, especially near the base.
Small, mobile insects moving quickly across the scalp surface.

The combination of flakiness and irritation can obscure the detection of nits, because the debris blends with the scales. Effective examination therefore requires a thorough parting of the hair and a magnified view of the scalp to separate lice‑related flakes from ordinary dandruff.

Treatment strategies target both the ectoparasite and the underlying dryness. Antilice shampoos reduce the insect population, while moisturising conditioners restore scalp hydration, decreasing flake formation and limiting further irritation.

«Other Skin Conditions»

A scalp covered with live insects and their eggs produces a distinct visual pattern: translucent ovoid structures attached to hair shafts, visible movement of tiny arthropods, and localized erythema from scratching. Several dermatologic disorders generate similar signs, yet lack the characteristic nits and motile parasites.

Seborrheic dermatitis – greasy scaling, yellow‑white plaques on the scalp, often extending to the eyebrows and nasolabial folds.
Psoriasis – well‑demarcated erythematous plaques with silvery‑white scales, frequently symmetrical and resistant to removal.
Atopic eczema – diffuse dryness, excoriated patches, occasional oozing, intensified by chronic scratching.
Folliculitis – pustular lesions centered on hair follicles, may produce crusted scabs but no adherent eggs.
Impetigo – honey‑colored crusts over eroded skin, typically confined to the face and neck rather than the hairline.
Scabies – tiny burrows in intertriginous areas, intense nocturnal itching, absent on the scalp of most adults.

Key diagnostic criteria differentiate true lice infestation from these conditions: presence of viable insects, detection of nits within 1 cm of the scalp, and rapid spread among close contacts. Microscopic examination of hair shafts confirms nit attachment, while skin biopsies or culture identify alternative pathologies. Prompt identification guides appropriate treatment, preventing unnecessary pesticide use or delayed therapy for the actual skin disorder.

«Hair Product Residue»

Hair product residue often accumulates on a scalp already hosting lice, altering the visual appearance of the head. The residue creates a visible film that can be mistaken for natural oil but is typically thicker and may form small clumps along the hair shaft. These clumps can obscure nits, making them harder to detect, while simultaneously highlighting the irregular texture of the hair.

Key visual indicators include:

A dull, sticky coating that reduces hair shine and adds a matte finish to the scalp.
Small, hardened particles that adhere to the base of hairs, sometimes resembling dandruff but denser.
Increased hair fragility; broken strands appear more frequently where residue has weakened the cuticle.
Presence of both live lice and empty egg casings (nits) amidst the residue, often visible as tiny, oval bodies attached close to the scalp.

The combined effect of lice and product buildup results in a scalp that looks unclean, with uneven distribution of texture and occasional patches of crusted material. Proper removal of residue, alongside lice treatment, restores the hair’s natural appearance and reduces the likelihood of misidentifying infestation signs.