Head Lice (Pediculosis Capitis)
Infestation of the scalp by human head lice; a nuisance, not a disease, and not a sign of poor hygiene.
Primary risk age: Most common in school-age children, 3–11 years.
- Urgency
- Mild
- Typical age
- Most common in school-age children, 3–11 years.
- Body system
- Infectious & Parasitic
Typical course: Live lice are usually cleared within a week or two with two correctly timed treatments plus combing.
Reviewed against AAP · CDC · WHO · NHS guidance Last reviewed 2026-06-13
1. Summary & Pathophysiology
Infestation of the scalp by human head lice; a nuisance, not a disease, and not a sign of poor hygiene.
Pathophysiology (Development Path)
Lice live on the scalp feeding on blood and lay eggs (nits) glued to hair shafts; their saliva causes the itch that develops over time.
Primary Causes & Etiology
Tiny wingless insects spread mainly by direct head-to-head contact and, less often, by shared combs, hats, or bedding.
2. Symptom Continuum
- Early Onset Signs
Itching of the scalp, especially behind the ears and at the nape of the neck, though many children have no symptoms at first.
- Progressive Phase
Visible lice or firmly attached nits near the scalp, scratching, and sometimes small red bumps or irritation.
- Severe Indicators
Scratched skin can become infected, with crusting, pus, or tender swollen neck glands.
3. Clinical Verification
Finding live lice or viable nits on close inspection, best done with a fine-toothed comb on wet conditioned hair.
4. Care & Elements Plan
Primary Care Treatment Plan
Apply a topical anti-louse treatment and remove nits by combing. A repeat treatment after about a week targets newly hatched lice. Treat close contacts who are affected.
Home Support Elements
Wet-comb conditioned hair every few days with a fine-toothed nit comb, wash recently used bedding and hats in hot water, and check household members. No need to treat the whole house or pets.
Generic Active Ingredients (No Brands)
- Permethrin (topical anti-louse active ingredient)
- dimeticone (physical, low-resistance topical agent that coats and immobilizes lice)
- wet-combing with conditioner (drug-free removal).
Lists active elements only. Never administer self-designed therapies.
5. Doctor Critical Lines
Critical Thresholds: When to See a Doctor
See a doctor if treatments fail, the scalp looks infected, the child is very young, or you are unsure of the diagnosis.
6. Vaccine & Prevention
Routine Prophylaxis (Prevention)
Avoid head-to-head contact, do not share combs or hats, and check children regularly during outbreaks; exclusion from school is generally not necessary.
Immunization Context
No vaccine is relevant to head lice.
7. Timelines & Outlook
Active Timeline
Live lice are usually cleared within a week or two with two correctly timed treatments plus combing.
Expected Prognosis
Excellent; lice are eliminated with correct, repeated treatment.
Potential Untreated Complications
Secondary skin infection from scratching, and distress or stigma, which are unwarranted.
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