Scabies Management

Keratolytics (Topical)

Example drugs: Ammonium lactate 12% lotion, Urea 10% cream, Salicylic acid

The removal of crust and scales with keratolytics is necessary for scabicide penetration of crusted scabies.

Ivermectin (Oral)

Oral Ivermectin is an effective treatment option for scabies patients unresponsive to preferred and alternative topical treatments. Combination therapy with topical scabicides is considered to be the best option for crusted scabies. Oral Ivermectin may have a role in the treatment of refractory infestations and immunocompromised patients or when administration of head-to-toe topical therapy would be difficult. This may also be used in scabies epidemics in institutions. Ivermectin interrupts GABA-induced neurotransmission of many parasites. The efficacy of oral Ivermectin is comparable with topical Permethrin and superior to Lindane.

Scabicides (Topical)

Benzyl Benzoate

Benzyl benzoate is effective in the management of Permethrin-resistant crusted scabies. Different treatment regimens have been used, but no comparative data has been published. This drug may be used alone or in combination with Sulfiram. This may be used with Ivermectin for patients with relapses after a single treatment of Ivermectin.

Crotamiton







Crotamiton can be used to treat nodular scabies in children but may require up to 5 days of treatment. This may be used for symptomatic relief from pruritus, but there is conflicting evidence of its efficacy. Crotamiton appears to be less effective as a scabicide than Permethrin and Lindane.

Ivermectin

Ivermectin lotion of 1% was reported to be as effective as 5% Permethrin cream.

Lindane (Gamma Benzene Hexachloride)

Lindane is used only as an alternative therapy in patients who are intolerant of other therapies or when other therapies fail due to the risk of neurotoxicity. When used properly, the 1% lotion is an effective scabicide with effects seen after a single 6-hour treatment. Lindane-resistant scabies has been noted in North, Central, and South America and in Asia. Lindane is not recommended in patients with crusted scabies due to the risk of toxicity.

Malathion

Overnight application of 5% aqueous preparation of Malathion is an effective treatment option. This is an alternative for patients when treatment with Permethrin is not appropriate.

Permethrin

Permethrin is the preferred treatment for children and adults, including pregnant and lactating women. The drug has higher efficacy than alternative topical treatments and has low toxicity. Permethrin impairs the function of voltage-gated sodium channels in insects, which leads to disruption of neurotransmission.

Spinosad

Spinosad causes fatal neuronal excitation in insects. A topical suspension of 0.9% Spinosad was approved in 2021 by the United States Food and Drug Administration for the treatment of scabies in adults and children ≥4 years old.

Sulfur

Sulfur is the oldest known treatment for scabies. This is safe and effective but requires application for three consecutive days. This is a treatment option for infants and pregnant women with scabies. Reproduction studies have not been conducted.

Other Therapies

Nodular scabies may be treated with corticosteroids after completing scabicide therapy. Oral antihistamines may be given to help alleviate pruritus. Medium- or high-potency topical steroids may also be given to help control pruritus after scabicide therapy. Secondary infections should be treated with appropriate antibiotics. 

Patient Education

Prevention of Disease Transmission

Patient and close physical contacts should be educated about scabies transmission and the necessary steps to prevent the spread. Individuals who came in close contact with the patient within an 8-week period prior to diagnosis should be identified and managed accordingly. It is important to treat infested individuals and their close physical contacts at the same time to avoid re-infestation. Infected individuals should avoid skin-to-skin contact with non-infected individuals. Advise patients to avoid close contact with partners until completion of treatment.

Hygienic measures should be undertaken to help avoid transmission by fomites. An infected individual should use clean or fresh clothing or bedding after treatment. Wash potentially contaminated clothes, towels, and bedding at a high temperature (>50°C) or store them in plastic bags for at least 72-96 hours. Laundry should be done the morning after treatment, not mixed with another person's clothing, segregated while wearing protective gear, and washed using hot water or tumble-dried on a hot cycle for at least 10 minutes. There is no need to clean coats, furniture, rugs, floors, or walls in any special manner.

Disease Treatment

Educate the patient and close physical contacts about the disease treatment. Patients should be made aware that itching may persist for up to 2–4 weeks after the end of appropriate treatment. The patient should be thoroughly educated about the application of the treatment and supplementation with written instructions may be helpful. Verbal and written instructions should include the amount of drug to be applied, how the treatment should be applied, and where to apply the treatment. For infants and young children, the entire body surface from the neck down should be covered and, if necessary, include the scalp and face (avoid the areas around the eyes and mouth). For older children and adults, apply from the neck down, with particular attention to intensely involved areas (eg folds, groin, navel, tips of the fingers, and under the nails, especially in crusted scabies). The skin should be kept cool and dry during treatment. If the patient applies the topical treatment, their hands should not be washed after application. If treatment is applied by a non-infected person, the person should wear disposable gloves. The nails should be cut short.

Crusted Scabies

Control of Disease Dissemination

In the case of crusted scabies, there is an increased risk of transmission. Strict isolation of the patient should be observed until cure is achieved. Avoidance of direct skin contact is achieved through the use of gloves and gowns by hospital staff. Protective equipment should be worn until 24 hours after the first therapy dose. Careful washing of the patient’s clothes, linens, towels, etc should be done. Both low- and high-risk patient contacts should be treated. High-risk contacts are persons with protracted or frequent skin contact (eg via the hands) with the infected individual and should be treated regardless of the presence of symptoms. Low-risk contacts are persons with indirect contact (eg via bedding) with the infected individual and only need treatment in the case of crusted scabies.