Scabies is a highly contagious skin infestation caused by the microscopic mite Sarcoptes scabiei var. hominis. This parasite burrows into the top layer of human skin, where the female mite lives and lays eggs. The primary objective of treatment is the complete eradication of the mites and their eggs to stop the cycle of infestation. While many people search for a “spray” to kill the mites, the most effective approach involves dual treatment: prescription medication for the body and environmental cleaning for the home.
Identifying Scabies and Mite Behavior
The most telling symptom of a scabies infestation is intense, persistent, nocturnal itching. This is the result of the body’s allergic reaction to the mites, their eggs, and their fecal matter. A characteristic rash often appears as tiny red bumps, blisters, or pimples, frequently located in areas like the web spaces between the fingers, wrists, elbows, knees, waistline, and genitals.
Occasionally, a thin, wavy, raised line, which represents the mite’s burrow in the skin, may be visible, though these tracks can be difficult to find. Transmission occurs most commonly through direct, prolonged skin-to-skin contact with an infested person. Transmission through shared items like clothing or bedding is less common, as the mite can survive off the human host for only about two to three days under normal indoor conditions. Symptoms may not appear for two to six weeks after initial exposure, but the person remains contagious during this time.
Approved Medical Treatments for the Body
Curing scabies requires prescription-strength treatments called scabicides. The most common first-line treatment is 5% Permethrin cream, a topical medication approved by the FDA for people as young as two months old. This cream is applied to the entire body, from the neck down to the soles of the feet, and must remain on the skin for eight to fourteen hours before being washed off. It is important to apply thoroughly, paying close attention to areas like the skin between the fingers and toes, under the nails, and in skin folds.
A physician may also prescribe oral Ivermectin, an antiparasitic medication. This is often used when topical treatments fail, during outbreaks, or for patients unable to apply cream to their entire body. Ivermectin is typically given in two doses, taken one to two weeks apart. The second dose is necessary because these medications do not reliably kill mite eggs, ensuring any newly hatched mites are killed before they can reproduce.
For severe cases, such as crusted (Norwegian) scabies, a combination of topical Permethrin and oral Ivermectin is often required. Proper application technique is essential; if the cream is not applied thoroughly or is washed off too soon, treatment can fail. Patients are sometimes advised to re-apply the topical medication to their hands immediately after washing them during the treatment period.
Environmental Decontamination Methods
Environmental decontamination is a necessary step to prevent reinfestation from items in the home. While specialized environmental insecticide sprays (miticides) are commercially available for use on surfaces, they must never be used on human skin. These products are intended for non-washable items like furniture, carpets, and mattresses, and should be used strictly according to the label’s instructions, often supplementing non-chemical cleaning.
The most effective methods for environmental disinfection rely on heat and isolation. All clothing, bedding, towels, and washcloths used by the infested person within the three days prior to treatment must be machine-washed in hot water, at temperatures exceeding 50°C (122°F). After washing, drying these items on the high-heat cycle is also highly effective at killing any mites or eggs.
For non-washable items, isolation is recommended. Mites generally cannot survive more than 72 hours away from human skin. Sealing items such as stuffed animals, shoes, or upholstered furniture in a tightly closed plastic bag for at least one week is sufficient to ensure the mites die from dehydration. Thorough vacuuming of carpets, rugs, and upholstered furniture is also a standard part of the cleaning protocol, and the vacuum bag must be discarded immediately after use.
Post-Treatment Care and Reinfestation Prevention
Following successful treatment, the intense itching and rash may not disappear immediately. A condition known as post-scabetic pruritus often causes symptoms to persist for up to two to four weeks, even after all mites have been killed. This persistent itching can usually be managed with over-the-counter or prescription anti-itch medications, such as antihistamines or topical corticosteroids.
The most common reason for treatment failure is reinfestation, which is why simultaneous treatment of all close contacts is mandatory. Every member of the household and any recent sexual partners must be treated at the same time as the primary patient, even if they show no symptoms. If symptoms continue or worsen two to four weeks after the initial treatment, seek medical advice immediately for re-evaluation and potential retreatment.