Head Lice (Pediculosis) - Symptoms, Causes & Treatment
Medically reviewed by Dr. Anand S. Urhekar, MD, MD Pathology, Clinical Advisor · Last updated July 2026
Infestation of the scalp with the human head louse, spread mainly by head-to-head contact among school-aged children. Itch develops from an allergic reaction to louse saliva and may take weeks to appear. Diagnosis requires finding a live louse, best done by wet-combing with conditioner.
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Quick Answer
Head lice are small insects living on the scalp, spread by head-to-head contact. Itch, especially behind the ears and at the nape, is the main symptom, but diagnosis requires seeing a live louse — wet-combing with conditioner and a fine detection comb is the most reliable check. Treatment is dimeticone lotion or wet-combing repeated on a schedule; treat only people with confirmed live lice.
Symptoms
- Itchy scalp, worst behind the ears and at the nape
- Live lice, 2–3 mm, moving on the scalp
- Nits (egg cases) firmly glued to hair shafts
- Scratch marks and occasionally secondary infection
- Often no symptoms at all in early infestation
Causes & Risk Factors
- Direct head-to-head contact
- Common in children aged 4–11 and their households
- Not related to hygiene or hair-washing frequency
- Rarely spread via shared combs, hats or pillows
Treatment & Management
- Dimeticone 4% lotion applied and repeated after 7 days
- Wet-combing with conditioner every 3–4 days for at least 2 weeks
- Treating all confirmed household cases on the same day
- Checking close contacts rather than treating everyone
- Avoiding repeated use of insecticides where resistance exists
When to See a Doctor
See a pharmacist or doctor if treatment has failed twice, if the scalp is weeping or crusted (bacterial infection), or if there is significant swelling of neck glands.
Frequently Asked Questions
Do nits mean an active infestation?
Not necessarily. Empty egg cases stay glued to hair for months after treatment. Only a living, moving louse confirms an active infestation and justifies treatment.
Does head lice mean poor hygiene?
No. Lice spread by head contact and are equally happy on clean hair. Frequent washing neither prevents nor cures an infestation.
Related Conditions
Medical References
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Medical Disclaimer: This information is for educational purposes only and is not intended as medical advice. The content on this page should not be used to diagnose or treat any health problem. Always consult with a qualified healthcare professional for proper medical evaluation, diagnosis, and treatment of your condition.