What is the treatment for scabies?

From the Guidelines

Scabies is treated primarily with topical permethrin 5% cream as first-line therapy, with a second application one week later recommended to kill newly hatched mites. This treatment approach is based on the most recent and highest quality study available, which prioritizes morbidity, mortality, and quality of life as the outcome 1. The treatment regimen involves applying the cream from neck to toes, leaving it on for 8-14 hours (typically overnight), and then washing it off. Alternative treatments include oral ivermectin (200 mcg/kg, repeated in 7-14 days), topical benzyl benzoate 25%, or topical sulfur ointment 5-10% 1.

Key Considerations

• All household members and close contacts should be treated simultaneously, even if asymptomatic, to prevent reinfestation.
• Clothing, bedding, and towels used in the past 3 days should be washed in hot water and dried on high heat.
• Itching may persist for 2-4 weeks after successful treatment due to hypersensitivity reactions to dead mites, and antihistamines and topical steroids can help manage this itching.
• For crusted (Norwegian) scabies, a combination of oral ivermectin and topical permethrin is often needed, sometimes requiring multiple doses 1.
• Special considerations should be taken for infants, young children, and pregnant or lactating women, with permethrin being the preferred treatment due to limited data on the safety of ivermectin in these populations 1.

Treatment Approach

• Topical permethrin 5% cream is the first-line treatment for scabies, with a second application one week later recommended to kill newly hatched mites.
• Oral ivermectin (200 mcg/kg, repeated in 7-14 days) is an alternative treatment option.
• Topical benzyl benzoate 25% or topical sulfur ointment 5-10% can also be used as alternative treatments.
• For crusted scabies, a combination of oral ivermectin and topical permethrin is often needed, sometimes requiring multiple doses 1.

From the FDA Drug Label

DOSAGE AND ADMINISTRATION Adults and children Thoroughly massage Permethrin Cream, 5% into the skin from the head to the soles of the feet. Scabies rarely infests the scalp of adults, although the hairline, neck, temple, and forehead may be infested in infants and geriatric patients. Usually 30 grams is sufficient for an average adult. The cream should be removed by washing (shower or bath) after 8 to 14 hours. Infants should be treated on the scalp, temple, and forehead. ONE APPLICATION IS GENERALLY CURATIVE. Patients may experience persistent pruritus after treatment. This is rarely a sign of treatment failure and is not an indication for retreatment. Demonstrable living mites after 14 days indicate that retreatment is necessary. INDICATIONS AND USAGE Permethrin Cream, 5% is indicated for the treatment of infestation with Sarcoptes scabiei (scabies). DOSAGE AND ADMINISTRATION: SHAKE WELL BEFORE USE. In Scabies: Thoroughly massage into the skin of the whole body, from the chin down, paying particular attention to all folds and creases. A second application is advisable 24 hours later. Clothing and bed linen should be changed the next morning. A cleansing bath should be taken 48 hours after the last application

The treatment of scabies involves:

• Permethrin Cream, 5%: applying the cream from the head to the soles of the feet, leaving it on for 8 to 14 hours, and then washing it off. One application is generally curative 2.
• Crotamiton (TOP): applying the lotion to the whole body from the chin down, with a second application 24 hours later 3. Key points:
• Permethrin Cream, 5% is indicated for the treatment of scabies 2.
• Demonstrable living mites after 14 days indicate that retreatment is necessary 2.

From the Research

Treatment Options for Scabies

• The first line therapy for scabies is topical application of permethrin, in accordance with the current recommendations for its use 4.
• Other treatment options include systemic ivermectin and topical crotamiton or benzyl benzoate 4, 5.
• A combination of permethrin and ivermectin is used to treat otherwise intractable cases and is generally indicated for the treatment of crusted scabies 4.

Efficacy of Permethrin and Ivermectin

• A study comparing the efficacy of permethrin 5% and oral ivermectin for the treatment of scabies found that two applications of permethrin with a one week interval was more effective than a single dose of ivermectin 6.
• Another study found that two doses of ivermectin is as effective as a single application of permethrin 6.
• A new treatment regimen with permethrin, applied once daily for two consecutive days, was found to be more effective than a single application in adult immunocompetent patients with scabies 7.

Application of Permethrin

• Current guidelines and medication labels instruct application of topical permethrin 5% cream from neck down for treatment of adult patients with scabies 8.
• However, there are cases where scalp involvement is observed, and scalp-to-toes application of permethrin may be necessary 8.
• The application of permethrin should be adapted case-by-case, according to feasibility, and it is still important to treat contacts 5.

Causes of Treatment Failure

• Known causes of treatment failure include improper application of the external agents, failure of repeated treatment with ivermectin, incomplete decontamination of furnishings and clothes, failure to simultaneously treat contact persons, absence of written documents explaining treatment modalities, and the patient's belonging to a risk group 4.