What are the symptoms and treatment options for scabies affecting the scrotum?

From the Guidelines

Scabies of the scrotum is a parasitic skin infestation caused by the Sarcoptes scabiei mite that requires prompt treatment with scabicides, and the recommended treatment is permethrin 5% cream applied to the entire body from the neck down, with special attention to the genital area, and left on for 8-14 hours before washing off, as recommended by the 2015 guidelines 1. The treatment should be repeated after 7 days, and alternative treatments include ivermectin (oral medication) at 200 mcg/kg, repeated after 1-2 weeks, or benzyl benzoate 25% lotion applied for 24 hours and repeated after 7 days.

• All clothing, bedding, and towels should be washed in hot water and dried on high heat to prevent reinfestation, as suggested by the guidelines 1.
• Sexual partners and household contacts should be treated simultaneously even if asymptomatic, as scabies is highly contagious through direct skin-to-skin contact, and this is recommended by the guidelines 1. The intense itching, which is typically worse at night, may persist for 2-4 weeks after successful treatment due to an allergic reaction to the dead mites and their waste products.
• Antihistamines or topical steroids may help manage this itching during recovery, and if symptoms persist beyond 4 weeks after completing treatment, a healthcare provider should be consulted for possible retreatment or to rule out other conditions, as recommended by the guidelines 1. It is essential to note that crusted scabies, a more aggressive form of the infestation, may require combination treatment with a topical scabicide and oral ivermectin, as recommended by the guidelines 1. In any case, it is crucial to follow the treatment guidelines and take preventive measures to avoid reinfestation and transmission to others.

From the FDA Drug Label

Permethrin Cream, 5% is indicated for the treatment of infestation with Sarcoptes scabiei (scabies). Thoroughly massage Permethrin Cream, 5% into the skin from the head to the soles of the feet. The treatment for scabies, including scabies of the scrotum, involves applying permethrin cream 5% to the entire body, from the head to the soles of the feet, including the genital area.

• Key points:
  • Apply permethrin cream 5% to the entire body.
  • Include the scrotum in the treatment area.
  • Leave the cream on for 8 to 14 hours before washing off 2, 2.

From the Research

Scabies Treatment

• The treatment of scabies typically involves the use of topical or oral medications, with permethrin and ivermectin being two commonly used options 3, 4, 5, 6.
• Topical permethrin, applied once daily, is considered an effective treatment for scabies, with a cure rate of 61.8% to 87.2% in adult immunocompetent patients 3.
• Oral ivermectin is also effective in treating scabies, with a cure rate of 63.1% to 84.2% at the 2-week and 4-week follow-up, respectively 5.
• The application of permethrin from scalp-to-toes may be necessary in some cases, particularly in infants or adults with scalp involvement 7.

Treatment Comparison

• A study comparing topical permethrin and oral ivermectin found that both treatments were equally efficacious, with a cure rate of 94.7% and 90% at the end of 4 weeks, respectively 4.
• Another study found that two applications of topical ivermectin were as effective as two applications of permethrin 2.5% cream at the 2-week and 4-week follow-up 5.
• Oral ivermectin is considered a safe, easy to use, and cost-effective treatment option, particularly in large populations or for those with crusted scabies 6.

Treatment Administration

• Topical permethrin is typically applied to the entire skin surface, left on for 24 hours, and repeated 7-10 days later 3.
• Oral ivermectin is typically taken in a single dose with food, with a retreatment dose given 10-14 days later to enhance effectiveness 6.
• The treatment dose for non-crusted scabies is 200 µg/kg, taken in a single dose with food 6.