From the Guidelines
Yes, permethrin topical treatment for scabies should be reapplied if it was only left on for 3 hours instead of the recommended 8-14 hours. The standard treatment regimen for permethrin 5% cream requires application from neck to toes (including under fingernails, between fingers and toes, and in skin folds) and leaving it on for 8-14 hours before washing off, as recommended by the 2015 guidelines for treatment of sexually transmitted diseases 1. If the medication was washed off prematurely after only 3 hours, its effectiveness may be significantly reduced as the medication needs sufficient contact time to kill the scabies mites and their eggs.
You should reapply the permethrin cream as soon as possible and follow the complete treatment instructions. Remember to treat all household members and sexual contacts simultaneously even if they don't have symptoms, as scabies is highly contagious. Additionally, wash all clothing, bedding, and towels used in the past 3 days in hot water and dry on high heat to prevent reinfestation. Permethrin works by disrupting the nervous system of the mites, and adequate exposure time is necessary for complete eradication. The most recent and highest quality study, which is the 2015 guidelines for treatment of sexually transmitted diseases 1, supports this recommendation, and it is essential to follow the recommended treatment regimen to ensure effective treatment of scabies.
Some key points to consider when treating scabies with permethrin include:
- Applying the cream to all areas of the body from the neck down
- Leaving the cream on for 8-14 hours before washing off
- Treating all household members and sexual contacts simultaneously
- Washing all clothing, bedding, and towels used in the past 3 days in hot water and drying on high heat to prevent reinfestation
- Following the complete treatment instructions to ensure effective treatment of scabies, as recommended by the 2015 guidelines for treatment of sexually transmitted diseases 1.
From the FDA Drug Label
DOSAGE AND ADMINISTRATION Adults and children ... The cream should be removed by washing (shower or bath) after 8 to 14 hours. ... Demonstrable living mites after 14 days indicate that retreatment is necessary. The patient was instructed to leave permethrin topical on for 8 to 14 hours, but it was only left on for 3 hours. Since the treatment duration was not as recommended, it may not be effective. However, the FDA drug label does not provide guidance on repeating the treatment if it was not left on for the recommended duration. Retreatment is only indicated if there are demonstrable living mites after 14 days 2.
From the Research
Permethrin Topical Treatment for Scabies
- The standard treatment regimen for permethrin topical involves leaving it on for 8-14 hours or as directed by a healthcare professional 3, 4.
- If permethrin was only left on for 3 hours, it may not be effective in treating scabies, as the recommended duration is not met.
- There is no direct evidence to suggest that repeating the treatment after only 3 hours is recommended or effective 3, 5, 6, 4, 7.
Repeating Permethrin Treatment
- The treatment can be repeated 7-10 days later if the initial treatment is not effective, as seen in some studies 3, 4.
- However, the decision to repeat the treatment should be based on the clinical diagnosis and evaluation of the patient's response to the initial treatment 5, 7.
- It is essential to follow the recommended treatment regimen and consult a healthcare professional for guidance on repeating the treatment.
Efficacy of Permethrin Treatment
- Permethrin is considered an effective treatment for scabies, with cure rates ranging from 63.1% to 94.7% in different studies 3, 4, 7.
- The efficacy of permethrin can be influenced by various factors, including the duration of treatment, the concentration of the cream, and the presence of resistance to the medication 5.