It should be noted that the application of topical medications immediately after a hot shower or bath can increase the absorption of these toxic chemicals  through the skin and into the bloodstream.  The skin should be completely dry, which may take up to an hour.

It is also reasonable to impregnate bedsheet or cotton bedshirt with permethrin (a contact insecticide), as is often recommended by travel authorities for the prevention of scabies and other bed bugs.

Ref: CDC & WHO literature
page 101 Manual of Travel medicine, Victorian Infectious diseases Service, Royal Melbourne Hospital, Melbourne, Australia. 1999