I wish I knew this as well. I used the prescribed permethrin 6 days ago and have seen no difference in my symptoms.
Hello,
According to American osteopathic college of dermatology, it is usual for itching and rash to continue for as long as two to four weeks after treatment of scabies. Hence a second application a week later is often advised. In some cases, repeat applications weekly are needed until cured.
I hope it helps. Take care and God bless.