Scabies
Questionnaire/history:
Intensely itchy rash?
- Especially at night?
Location:
- Between fingers?
- Wrists?
- Flexor surfaces?
- Skin folds?
--- Breast creases?
--- Genitals?
--- Buttocks?
Contacts (all people with whom skin-to-skin contact has been made for a prolonged period within the previous 2 months)?
(Note: all of those are at risk of scabies and should be informed)
Past medical history?
- Immunocompromise?
Current medication?
Known drug allergies?
Examination:
Burrows as small, greyish lines in the web spaces and flexor surfaces?
- Scalp?- Face?
- Hands (eg palms)?
- Wrists?
- Ankles?
- Feet (eg soles)?
Secondary eczema-like rash?
Secondary infection?
Diffuse truncal eruption (in older people)?
Crusted (‘Norwegian’) scabies (resistant to routine treatment)?
(Note: If crusted scabies, consider the possibility of underlying immunodeficiency and investigate if appropriate)
Management:
Advised:
Clothing and bed linen belonging to the index case should be washed
All members of the house should be treated within 24 hours simultaneously
Topical permethrin: 2 applications 1 week apart
Topical crotamiton less effective than permethrin
(Note: Both of these preparations are considered superior to topical malathion and benzyl benzoate which have insufficient evidence to judge their efficacy. These are often used as second-line agents but lack evidence of efficacy. Malathion is recommended if permethrin allergy)
Insecticides can be purchased over the counter
Malathion 0.5% aqueous liquid can be purchased for children/adults over 6 months
Children under 2 years old require a prescription for permethrin 5% dermal cream
Crotamiton lotion may help the itching and may improve cure rates
A topical corticosteroid may be used after scabies has been successfully treated (ie after the second application)
Oral sedating anti-histamine at night may be helpful
The itch and associated eczema may persist for some weeks after the infestation has been eliminated
Referral/seek advice:
Children < 2 months
Resistant or severe cases (incl. crusted scabies)
Ongoing symptoms 2-4 weeks after last treatment application
May need oral Ivermectin (only available on a ‘named patient basis’)
Guidance for topical treatment of scabies (based on BNF):
Use permethrin 5% cream first line, apply 5% preparation to the whole body and wash off after 8 to 12 hours
Apply twice, one week apart
For a single whole body application, you need 30-60 g of cream
Do not apply after a hot bath, as this may increase absorption into the blood
Treatment should be applied to the whole body, including the scalp, neck, face and ears (despite the manufacturer's recommendation to exclude the head and neck)
Particular attention should be paid to the webs of the fingers and toes, and lotion brushed under the ends of the nails
Avoid contact with the eyes and do not use on broken skin
People with hyperkeratotic crusted scabies may need 2 or 3 applications of treatment on consecutive days
Resource(s):
CKS 2022PHE/NICE antimicrobial prescribing
Information for patient/carer(s):
British Association of Dermatologists: Scabies