Examqo › Examqo library › Family medicine › Skin · IMLE
Scabies and head lice
In scabies the night-time itch of the whole household is the clue, and treatment must be simultaneous for all close contacts and repeated after a week; in head lice the diagnosis is a live louse, and treatment is wet combing or a topical product, repeated.
Why it matters in the exam
The exam presents a toddler with widespread itch worse at night, a child who has started kindergarten with an itchy scalp and nodes behind the ears, and questions about treatment: who is treated, how many times, and what to do with the bedding. A constant question: itch that persists after correct treatment — failure or the expected course?
Remember that in infants scabies also appears on the palms, soles and head, and that crusted scabies in immunosuppressed and institutionalised older patients is highly contagious and needs ivermectin.
Both conditions spread in group settings — kindergartens, schools and institutions — so explaining correct, simultaneous treatment to the parents matters as much as the prescription.
In a nursing home or a ward, an outbreak of scabies requires treating all residents and staff in contact at the same time, because a single case of crusted scabies can infect dozens of people. In a child with an itchy scalp and nodes behind the ears think first of lice; in a child with night-time itch of the body and itching relatives — of scabies. The distinction decides who is treated and how, and prevents repeated, unnecessary treatments.
Key points
- Scabies: night-time itch, burrows, itchy household members.
- Permethrin 5% for all contacts on the same day, repeated after 7 days.
- Itch after treatment lasts up to 2–4 weeks.
- Lice: diagnosis by a live louse; treat and repeat after 7–10 days.
- Crusted scabies — ivermectin and contact isolation.
Summary table
| Condition | Presentation | Treatment | Remember |
|---|---|---|---|
| Scabies | Intense night-time itch, burrows between the fingers, wrists, waist, genitals; family members itch | Permethrin 5% from the neck down, 8–14 hours, repeat after 7 days | All close contacts on the same day |
| Scabies in an infant | Palms and soles, scalp and face | Permethrin on the head and face too (avoiding eyes and mouth) | Can be used from 2 months |
| Crusted scabies | Thick scales, immunosuppressed and older patients | Oral ivermectin with topical treatment | Highly contagious; contact isolation |
| Head lice | Scalp itch, nits close to the hair root, occipital nodes | Wet combing or permethrin 1% / dimeticone, repeat after 7–10 days | Diagnosis: a live louse |
| After treatment | Itch lasting up to 2–4 weeks | Emollient, antihistamine | Not treatment failure |
In the full version for subscribers
- A simple algorithm
- Memory aid
- Exam traps
- 5 review cards
- Enough for IMLE
The full version is open to subscribers of: Family medicine, Medical licensing exam (IMLE), Dermatology and venereology, Pediatrics.
Subscriber? Read the full topic Plans and prices 25 free questions
Sources
- CDC, 2024 — Scabies and head lice: clinical care and treatment
- American Academy of Pediatrics, Clinical Report, 2022 — Head lice
- European guideline for the management of scabies (IUSTI), 2017 — Diagnosis and treatment
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.