Clinical Review

Permethrin treatment in scabies infestation: importance of the correct formulation

BMJ 2000; 320 doi: http://dx.doi.org/10.1136/bmj.320.7226.37 (Published 01 January 2000) Cite this as: BMJ 2000;320:37
  1. N H Cox, consultant
  1. Department of Dermatology, Cumberland Infirmary, Carlisle CA2 7HY
  • Accepted 5 July 1999

See p 35

In temperate countries there are epidemics of the mite infestation scabies (figs 1 and 2) every 20-30 years. The present epidemic of scabies in the United Kingdom originated in the catchment population of this hospital in early 1990 and continues to be a problem.1 Failure to treat contacts adequately and to apply treatment correctly are acknowledged problems. Cases in which genuine resistance of scabies mites seems probable have also been reported. The following cases illustrate a new pitfall that can lead to treatment failure.

Fig 1

Scabies mite extracted from a burrow

Case reports

Family 1

A 53 year old woman and her husband acquired scabies—probably from their 25 year old son. They were all treated with topical permethrin, which was purchased “over the counter” from the pharmacist on the advice of their general practitioners. Over a period of six months the family used at least five bottles of permethrin and applied it for up to 24 hours, but with no success. Affected members consulted different general practitioners in two separate practices, and part of the reason for treatment failure may have been the fact that they were not treated concurrently from the outset. Shortly before the woman was due to attend a dermatology clinic, the family treated themselves with a malathion preparation (Derbac-M, Seton Scholl), and their symptoms resolved rapidly. The woman kept her appointment because of the duration and intensity of her symptoms (the other family members were not examined as their symptoms had resolved). At the consultation it was learned that they had been using a 1% permethrin cream rinse for head lice (Lyclear, Warner Lambert), which is not formulated to eradicate scabies infestation. The patient had apparently queried the suitability of the product at the …

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