Synopsis
Recognise classic and crusted scabies, treat the entire exposure network correctly and distinguish lice and environmental ectoparasites requiring different examination, product and control pathways.
- Scabies is caused by Sarcoptes scabiei mites burrowing in the stratum corneum; intense nocturnal itch and similarly affected close contacts are key clues.
- Typical burrows and papules involve finger webs, flexor wrists, axillae, waist, buttocks, genital skin and breasts; the adult head is usually spared.
- First-line treatment is permethrin 5% cream applied meticulously to the whole required skin surface, left for 8 to 12 hours and repeated after seven days.
- Treat all household and close skin contacts at the same time even if asymptomatic because sensitisation and symptoms can be delayed.
- Reapply topical treatment to hands after washing and include under nails, between digits, soles, buttock cleft, genital skin and other commonly missed sites.
- Crusted scabies needs specialist combination therapy, repeated dosing and strict contact precautions; a single routine permethrin application is inadequate.
- Itch can persist for several weeks after successful eradication; diagnose failure from new burrows, live mites, incorrect application or untreated contacts rather than itch alone.
- Head lice require detection of live lice before treatment; wet-combing or a licensed physical insecticide pathway differs from scabies treatment and bedding fumigation is unnecessary.
Key red flags
Hyperkeratotic widespread scale or crust in immune compromise suggests highly contagious crusted scabies.
Hypotension, fever, spreading erythema or rapidly painful skin suggests secondary bacterial infection and sepsis.
Institutional clustering in a care home, ward, prison or shelter requires coordinated outbreak management.
Infants, pregnancy, breastfeeding, frailty and immune compromise change treatment application and product choice.
Eyelash or eyelid lice require careful specialist product selection to avoid ocular toxicity.
Persistent symptoms with no mites after correct treatment may be post-scabetic inflammation rather than ongoing infestation.
Thick widespread scale, fissuring and crusting with variable itch in frailty or immune compromise indicates a very high mite burden.
Investigation priorities
Identify distribution, burrows, nodules, crusting, secondary infection and commonly missed treatment sites.
Management branches
Clinical or microscopic findings support classic scabies without crusted disease.
- Provide written instructions and enough permethrin 5% cream to cover the whole required surface, including folds, genital skin, buttock cleft, soles, interdigital and subungual sites.
- Apply to cool dry skin, leave for 8 to 12 hours, reapply to hands after washing and wash off after the exposure period.
- Repeat the complete application after seven days to kill mites emerging from eggs and treat every household and close skin contact simultaneously.
- Use emollient, topical corticosteroid or antihistamine symptom care as appropriate and review only when new burrows, live mites or persistent unexplained disease suggests failure.