Lice Organism-Specific Therapy 

Updated: May 03, 2018
  • Author: Darvin Scott Smith, MD, MSc, DTM&H; Chief Editor: Michael Stuart Bronze, MD  more...
  • Print

Therapeutic Regimens for Head, Body, and Pubic Lice

Patients generally present to a health care provider after discovering lice or nits on their person. Pruritus is the most common symptom of infestation, and combing and visual inspections have value in the diagnosis of lice infestation.

Treatment recommendations for Pediculus humanus capitis (head lice), Pediculus humanus corporis (body lice), and Phthirus pubis (pubic lice, crabs), as well as special considerations, are provided below. [1, 2, 3]

P humanus capitis

See the list below:

  • Permethrin 1% lotion: Apply to hair after washing with shampoo; use a sufficient amount to saturate the hair and scalp; leave on hair for no longer than 10min, and then rinse with water and towel dry; if lice are observed within 7d after application, apply a second treatment; remove any remaining nits with the nit comb provided or

  • Malathion 0.5% lotion: Apply lotion on dry hair in an amount just sufficient to thoroughly wet the hair and scalp; wash hands after applying to scalp; allow hair to dry naturally; do not use an electric heat source, and allow hair to remain uncovered; after 8-12h, shampoo the hair; rinse, and use a fine-toothed (nit) comb to remove dead lice and eggs; if lice are still present after 7-9d, repeat with a second application of malathion or

  • Benzyl alcohol 5% lotion: Apply lotion to saturate the hair and scalp, especially behind the ears and on the back of the neck; leave lotion on hair for 10min, and rinse with water; repeat treatment after 7d or

  • Spinosad: Apply to dry scalp and hair using only the amount needed to cover the scalp and hair; rinse off with warm water after 10min; repeat treatment if live lice are seen 7d after first treatment or

  • Pyrethrin and piperonyl butoxide (avoid in patients with allergy to chrysanthemum or ragweed): Various over-the-counter (OTC) products exist; apply to dry hair; after 10min, massage with water to foam, then rinse; repeat in 7-10d or

  • Ivermectin (off-label use): 200 μg/kg PO for 2 doses separated by 10d [4]

  • *Lindane shampoo: Apply the shampoo directly to dry hair without adding water; work the shampoo thoroughly into the hair, and allow to remain in place for 4min only; after 4min, add small quantities of water to hair until a good lather forms; immediately rinse all lather away; towel briskly, and then remove nits with nit comb or tweezers (do not cover the hair with shower cap or towel; avoid unnecessary contact of lather with other body surfaces); do not re-treat or use Lindane shampoo as a routine shampoo;  contraindicated in infants, children, women who are pregnant or nursing, elderly, persons with seizure disorders, persons who weigh < 110lb, and persons with itching/sores where lotion will be applied

*NOTE: Lindane is potentially neurotoxic and is considered a second-line drug for scabies in the event of failure of other medicines.   The World Health Organization classifies lindane as "Moderately Hazardous". Since 2009, it is restricted and regulated under the Rotterdam Convention.  It is not available in certain states such as California, although there is a specific exemption to the general ban, allowing it to  be used as a second-line pharmaceutical treatment for lice and scabies in some places.

P humanus corporis

Body lice can be treated by hygiene alone: Weekly clothing changes and laundering clothing and bedding are recommended; medication is optional and identical to the options used for head lice.

P pubis

P pubis is commonly transmitted by sexual contact. Patients with P pubis present to health care providers because they experience pruritus or because they notice the lice or nits in their pubic hair. [1, 2, 3]  See the following:

  • Permethrin 1% cream: Apply the cream to the affected area; wash off after 10min or

  • Pyrethrin and piperonyl butoxide mousse (may trigger allergies in those allergic to chrysanthemum or ragweed): Apply the mousse to the affected area; wash off after 10min or

  • Malathion 0.5% lotion: Apply the lotion for 8-12h, and wash off or

  • Lindane shampoo: Apply the shampoo to the affected area for 4min, and wash off; contraindicated in infants, children, women who are pregnant or nursing, the elderly, persons with seizure disorders, and persons with itching/sores where the lotion will be applied or

  • Ivermectin topical (Sklice): Apply 0.5% lotion to dry hair in amount sufficient (up to one 4-oz tube) to thoroughly coat the hair and scalp; leave lotion on hair for 10 minutes, and then rinse with water; for single use only (do not retreat) [4] or

  • Ivermectin (off-label use): 250 μg/kg PO, repeated in 2wk [4]

Special considerations

It is important to ensure that individuals with body and/or pubic lice wash their clothes, towels, and bedding with hot water and dry them using the hot setting on the dryer; dry cleaning or sealing clothes in plastic bags for 2wk is also acceptable.

Head lice resistance to permethrin is rising rapidly; in resistant cases, consider a greater concentration of permethrin or longer treatment exposure before attempting different therapies.

Sexual partners of those with pubic lice should likewise be treated, and sexual contact should be avoided until the lice infestation is successfully cured.

P humanus corporis is the only variety that can transmit other diseases, particularly typhus.