Lice attach to hair and lay their eggs (nits) on the hair shaft. Consider advising patients to shave the pubic hair prior to application of topical medications. Hair in the axilla and chest and abdomen can also be shaved if infested.
Recommended Regimens for treatment of head lice
The American Academy of Pediatrics provides guidelines for treating head lice (Frankowski BL, Bocchini JA Jr; Council on School Health and Committee on Infectious Diseases. Head lice. Pediatrics. 2010;126:392-403). Those guidelines in a condensed and edited form are provided below.
Use OTC permethrin 1% or pyrethrins. Malathion 0.5% can be used in people who are 24 months of age or olderwhen resistance to permethrin or pyrethrins is documented orwhen treatment with these products fails despite their correctuse.
Pediculicides Permethrin (1%) (Nix [Pfizer Consumer Health Care Group, New York, NY. The product is applied to damp hair that is first shampooed with a nonconditioning shampoo and then towel dried. It is left on for 10 minutes andthen rinsed off. Permethrin leaves a residue on the hair thatis designed to kill nymphs emerging from the 20% to 30% of eggsnot killed with the first application. The application is repeated in 7 to 10. An alternate treatment schedule on days 0, 7, and 13 to 15 has been proposed for nonovicidal products.
Pyrethrins Plus Piperonyl Butoxide (RID [Bayer, Morristown,NJ], A-200 [Hogil Pharmaceutical Corp, Purchase, NY], R &C [GlaxoSmithKline, Middlesex, United Kingdom], Pronto [DelLaboratories, Uniondale, NY], Clear Lice System [Care Technologies,Darien, CT]). These products are available in shampoo ormousse formulations that are applied to dry hair and left onfor 10 minutes before rinsing out. Retreat in 9 days. An alternateschedule of 3 treatments with nonovicidal products on days 0,7, and 13 to 15 has been proposed.
Malathion (0.5%) (Ovide [Taro Pharma, Hawthorne, NY]) is available by prescription as a lotion thatis applied to dry hair, left to air dry, then washed off after8 to 12 hours. The product should be reapplied in 7to 9 days if live lice are still seen. The highalcohol content of the product (78% isopropyl alcohol), makes it highly flammable. Do notuse a hair dryer, curling iron, or flat iron while the hairis wet; and do not smoke near a child receiving treatment. The product is contraindicatedin children younger than 24 months.
Benzyl Alcohol 5% Benzyl alcohol 5% (Ulesfia [Sciele Pharma, Atlanta, GA]) is approved for treatment of head lice in children older than 6 months. Benzyl alcohol is available by prescription. It is to be applied topically for 10 minutes andrepeated in 7 days, although as with other nonovicidal products, consideration should be given to retreating in 9 days or using 3 treatment cycles (days 0, 7, and 13–15).
Lindane (1%) is an organochloride that has central nervous system toxicityin humans; several cases of severe seizures in children usinglindane have been reported. Lindane is no longer recommendedby the American Academy of Pediatrics.
Removal of Topical Pediculicides All topical pediculicides should be rinsed from the hair overa sink rather than in the shower or bath to limit skin exposureand with warm rather than hot water to minimize absorption attributableto vasodilation.
Topical Reactions Itching or mild burning of the scalp caused by inflammation of the skin in response to topical pharmaceutical agents canpersist for many days after lice are killed and is not a reasonfor re-treatment. Topical corticosteroids and oral antihistaminesmay be beneficial for relieving these signs and symptoms.
Oral Agents Used Off-Label for Lice Ivermectin (Stromectol [Merck & Co, West Point, PA]) isan anthelmintic agent. A single oral dose of 200 µg/kg, repeated in 10 days, has been shown to beeffective against head lice. A single oral dose of 400 µg/kg repeated in 7 days has been shown tobe more effective than 0.5% malathion lotion. Ivermectin may cross the blood/brain barrier and block essential neural transmission; young children may be at higher risk of this adverse drug reaction. Therefore, ivermectin should not be used for children who weighless than 15 kg. Ivermectin is not FDA approved for treating lice.
“Natural” Products Several products are marketed for treatment of head lice. HairClean 1-2-3 (Quantum Health, Eugene, OR) [anise, ylang-ylang, coconut oils, and isopropyl alcohol]. The safety and efficacy of herbal products are currently not regulated by the FDA the same as medications.
Occlusive Agents Occlusive agents applied to suffocate the lice are widely usedbut have not been evaluated for effectiveness (mayonnaise, tub margarine, herbal oils, olive oil.
Manual Removal Manual removal of nits (especially the ones within 1 cm of the scalp) after treatmentwith any product is recommended by some. Fine-toothed “nit combs” are available. Although effective for removing lice and eggs, shaving the head generally is not recommended, because it can be distressing to a child or parent.
Pediculicide Resistance When faced with a persistent case of head lice after conventional treatment, benzyl alcohol 5% can be prescribed if the patient is older than 6 months, or malathion 0.5% can be prescribed if the patientis older than 24 months if safe use can be reasonably ensured.For younger patients, or if the parent cannot afford or doesnot wish to use a pediculicide, manual removal via wet combing or an occlusive method may be recommended, with emphasis oncareful technique and the use of 2 to 4 properly timed treatment cycles.
Recommended Regimens for treatment of pubic lice
The centers for disease control and prevention recommend the following for pediculosis pubis (pubic lice).
Permethrin 1% cream rinse applied to affected areas and washed off after 10 minutes
Pyrethrins with piperonyl butoxide applied to the affected area and washed off after 10 minutes
Malathion 0.5% lotion applied for 8–12 hours and washed off
Ivermectin 250 µg/kg orally, repeated in 2 weeks
Resistance is widespread. Malathion can be used when treatment failure is believed to have resulted from drug resistance. The odor and long duration of application for malathion make it a less attractive alternative than the recommended pediculicides. Ivermectin has been successfully used to treat lice, but it has only been evaluated in studies involving a limited number of participants.
Other Management Considerations
The recommended regimens should not be applied to the eyes. Pediculosis of the eyelashes should be treated by applying occlusive ophthalmic ointment to the eyelid margins twice a day for 10 days. Bedding and clothing should be decontaminated (i.e., either dry cleaned or machine-washed and dried using the heat cycle) or removed from body contact for at least 72 hours. Fumigation of living areas is not necessary.
Patients with pediculosis pubis should be evaluated for other sexually transmitted diseases (STDs).
Patients should be evaluated after 1 week if symptoms persist. Retreatment might be necessary if lice are found or if eggs are observed at the hair-skin junction. Patients who do not respond to one of the recommended regimens should be retreated with an alternative regimen.
Management of Sex Partners
Sex partners that have had sexual contact with the patient within the previous month should be treated. Patients should abstain from sexual contact with their sex partner(s) until patients and partners have been treated and reevaluated to rule out persistent disease.
Pregnant and lactating women should be treated with either permethrin or pyrethrins with piperonyl butoxide; lindane and ivermectin are contraindicated in pregnancy and lactating women.
Patients who have pediculosis pubis and also are infected with HIV should receive the same treatment regimen as those who are HIV negative.