Scabies is a common skin condition resulting from an infestation by tiny mites called Sarcoptes scabiei. These microscopic parasites burrow into the outer layer of the skin, leading to intense itching and a rash. Permethrin cream is a primary treatment option for eradicating these mites and alleviating the associated discomfort.
How Permethrin Works Against Scabies
Permethrin is a synthetic pyrethroid, a class of insecticides designed to mimic natural compounds found in chrysanthemum flowers. It acts on the nervous system of scabies mites, specifically targeting their nerve cell membranes. Permethrin disrupts the flow of sodium ions through channels in these membranes, leading to uncontrolled nerve firing. This overstimulation causes paralysis and ultimately results in the death of the mites. For effective treatment, the cream must be applied thoroughly to all skin surfaces, typically from the neck down to the soles of the feet, and left on for a specific duration.
The Scabies Eradication Timeline
Permethrin typically begins to kill scabies mites within 8 to 14 hours of proper application. While a single application kills existing mites, it often does not eliminate all mite eggs. A second treatment is recommended 7 to 14 days after the first to target newly hatched mites. This two-step approach ensures that any mites hatching after the initial treatment are also eradicated.
What to Expect After Treatment
After permethrin treatment, itching and rash commonly persist, and may even worsen, before improving. This occurs because the body continues to react to dead mites, their eggs, and waste products within the skin, triggering an allergic response. This post-treatment itching can last for several weeks, typically up to 2 to 4 weeks. Managing this often involves over-the-counter remedies like antihistamines or steroid creams, and it is important to distinguish this lingering irritation from a new infestation. New burrows or persistent new rashes after 2 to 4 weeks might indicate ongoing activity.
When Scabies Persists or Returns
Scabies can persist or return for several reasons following permethrin treatment. Improper application of the cream is a factor, where not all affected skin areas are adequately covered or the cream is not left on for the recommended time. Re-infestation from untreated household members or close contacts is another cause, as scabies spreads through direct skin-to-skin contact. All individuals in close contact with an infested person should be treated simultaneously. If symptoms continue or new lesions appear after the complete treatment course, consulting a doctor is important to assess for re-infestation or consider alternative treatments.