Treatment

Treatment options include the following:(1)

• Permethrin cream
• Ivermectin oral tablets
• Spinosad suspension
• Benzyl benzoate lotion
• Sulfur lotion
• Malathion lotion.

The preferred acaricide is permethrin 5% cream first line then malathion 0.5% liquid if necessary:

• on the basis of efficacy and tolerability data, permethrin is the drug of choice for scabies and malathion should be used as second line-treatment
  • use permethrin 5% dermal cream first-line unless contraindicated, as this is best supported by evidence (2)
    
    
• an aqueous preparation of permethrin is now the treatment of choice in children of all ages (3) - it is easy to apply, non-irritant, and has low mammalian toxicity; permethrin 5% cream is licensed for adults and children 2 months and above
  
  
• if permethrin allergy:
  • then malathion 0.5% aqueous liquid is the suggested choice (4)
    
    
• the entire body, except head and neck, must be treated
  
  
• the lotion is applied with a small paint brush or cotton wool ball and allowed to dry before the patient redresses. The treatment is applied to cool dry skin and is applied to the whole body (except the head and neck), paying particular attention to the webs of the fingers and toes. It is important that nails should be clipped back and any debris removed before applying treatment
  
  
• in children up to about 2 years of age, immunocompromised patients, older people and in people in whom treatment has failed, application should be extended to neck, ears, face and scalp (3)
  
  
• patients should NOT have a hot bath prior to treatment - this is because this may increased absorption of the ascaricide into the blood and so remove it from the site of action on the skin, and increase the risk of systemic unwanted effects (3)
  
  
• the application can be washed off in a hot bath after 8-12 hours (permethrin preparations). Malathion preparations are washed off after 24 hours
  
  
• the British National Formulary recommends that permethrin or malathion should be applied twice, 1 week apart over the whole body and washed off after 24 hours. If hands are washed with soap within 24 hours they should be retreated. (5).

Benzyl benzoate should is not, in general, used as a first-line treatment option for scabies

• two to three applications of benzyl benzoate at 24 hour intervals are required.

Clothing and bed linen should be washed and all household and close contacts treated simultaneously even in the absence of symptoms (6).

Pruritus may continue for several days and is usefully treated with crotamiton cream or lotion or combined crotamition and mild steroid preparations (e.g. Eurax-hydrocortisone (R)) - crotamiton also has mild antiscabetic action. If itching is disturbing the sleeping a sedating oral antihistamine can be used at night for temporary relief (3). Scabies that has become infected should be treated empirically for 7 days using oral antibiotics (3).

Ideally review the patient after 7-10 days.

Contacts (4)

• this includes anyone living in the same house, partners and others who have significant contact though child care eg in some situations grandparents
• remember other contacts can be infected with scabies but remain asymptomatic for several weeks
• all such contacts need to be managed in exactly the same way as the patient, however for most only one treatment is needed. Only symptomatic contacts require two treatments

Severe or crusted scabies (2)

• ivermectin as a single dose of 200 micrograms/kg, further doses of 200 micrograms/kg may be required
• alternatively frequent applications of permethrin, sometimes for several weeks
• Public health must be informed if it occurs in an institution such a nursing home

Discussion with / referral to a dermatologist should be considered in the following cases (4):

• diagnostic uncertainty / failure to respond to adequate treatment of the patient and contacts
• an outbreak in a nursing or other care home

Key points (4):

• First choice permethrin:
  • treat whole body from ear/chin downwards and under nails
  • if using permethrin and patient is under 2 years, elderly or immunosuppressed, or if treating with malathion: also treat face and scalp
• Home/sexual contacts:
  • treat within 24 hours. It is important that sexual, close personal, and household contacts are also treated, regardless of whether symptoms are present or not, because individuals may be infested without having symptoms. In addition, recently worn clothing and bed sheets should be washed at 60°C or higher (≥140°F) and dried the day after the first treatment to decrease the chance of re-infestation. (7)

Reference:

1. Hardy M, Engelman D, Steer A. Scabies: A clinical update. Aust Fam Physician. 2017;46(5):264-268.

2. Currie BJ, McCarthy JS. Permethrin and ivermectin for scabies. N Engl J Med. 2010 Feb 25;362(8):717-25.

3. Gunning K, Kiraly B, Pippitt K. Lice and Scabies: Treatment Update. Am Fam Physician. 2019 May 15;99(10).

4. Public Health England (June 2021). Managing common infections: guidance for primary care

5. BNF September 2023

6. Management of scabies. British Association for Sexual Health and HIV (2016)

7. Heukelbach J, Feldmeier H. Scabies. Lancet. 2006 May 27;367(9524):1767-74.