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When Lice Won't Leave

Consultant for PediatriciansConsultant for Pediatricians Vol 9 No 2
Volume 9
Issue 2

A MOTHER ASKS: “In the past month, I’ve used a pharmacist- recommended anti-lice shampoo 4 times and my daughter still has lice. Can you call in a prescription to get rid of them?”

A MOTHER ASKS:“In the past month, I’ve used a pharmacist-recommended anti-lice shampoo 4 times and my daughter still has lice. Can you call in a prescription to get rid of them?”

Lice that won’t leave is a monthly-if not weekly-telephone triage topic in some pediatric practices. Repeated applications of over-the-counter (OTC) products frequently fail to eliminate resistant lice (while unnecessarily increasing the child’s exposure to potentially harmful chemicals1). However, simply phoning in a prescription for a pediculicide is not recommended. The patient may indeed need a prescription medication, but an in-clinic visit allows time for adequate information gathering, examination, and education about how best to eradicate lice in an individual patient and his or her household. In addition, it is important to confirm that the diagnosis is correct, to ascertain whether medications are being administered properly, and to determine whether reinfestation or resistance is the problem.2

Is it really lice? When OTC lice products seem to be ineffective, the diagnosis of pediculosis capitis needs to be confirmed. Although diagnosing head lice is not typically difficult, a thorough head inspection, especially in a child who has thick, tangled hair or excessive scaling due to seborrhea, may take several minutes to perform properly. Parents often mistake dandruff or other debris for nits. Also, many schools enforce a “no nit” policy, requiring children in whom nits are found to stay home even when no more live lice are detected. This can lead parents to believe that their child still has lice, even though in some cases the infestation may have resolved.

Reinfestation or resistance? If live lice are found, then it must be determined whether reinfestation or resistance is the problem, since the focus of treatment will differ for these 2 scenarios. Distinguishing between reinfestation and resistance may not be an easy task.3 Reported criteria for identifying resistance include the presence of live lice after 2 to 3 days of a properly applied anti-lice treatment or the presence of live lice after 2 correctly applied treatments.4 The ideal way to establish that treatment has failed is to examine the patient within a few days of product application but before potential reexposure3; this cannot be accomplished over the telephone.

Management of lice reinfestation. If you determine that reinfestation is the problem, then first-line treatments may still be effective. Over the years, a wide variety of anti-lice products have

been used; the Table lists only those interventions most commonly used in children now. Note that lindane has not been included in this Table because it is not often used by pediatricians owing to its potential for neurotoxicity (lindane carries a black box warning banning its use in persons who weigh less than 110 lb1). Also absent from the Table is a newly approved topical treatment- benzyl alcohol lotion.

The products most often used as first-line therapy (1% permethrin lotion, pyrethrin-based shampoos) are available OTC. First-line anti-lice products typically require 2 applications separated by 10 days.

In addition to restarting pharmacotherapy, it is important to address potential reasons for reinfestation. To prevent reinfestation, close contacts of the affected child should be examined and treated if nits or live lice are found within 1 cm of the scalp.2 Any bedmates of the affected child should receive simultaneous prophylactic treatment; however, prophylaxis is not recommended for other contacts who show no evidence of infestation.5

The 2009 Red Book states that supplemental measures (cleaning of headgear, clothing, and bedding) are not always required to eliminate the problem and that disinfection of personal items is not likely to be useful.5 Frankowski and colleagues2 recommend the cleaning of all personal items belonging to the infected child, along with any household items, such as furniture or carpeting, that came in contact with the patient’s head within the 48 hours preceding initiation of treatment. Insecticides should not be sprayed around a home or day-care center. Maunder6 explains that lice cannot remain viable for long periods in the environment or on personal items not in contact with the human host and that transmission of lice requires that the hosts be in contact with each other.

Advise parents that a child’s readmission to day care or school should occur after completion of the first anti-lice treatment.7 School contacts should not be treated prophylactically, but head inspection of friends and other close schoolmates is advised, with subsequent treatment of all who are found to be infected.

Management of infestation with resistant lice. Treatment of resistant cases requires further pharmacological therapies. When it has been determined that a persistent lice infestation is the result of resistance to first-line agents, pediatricians frequently prescribe malathion. Oral agents such as trimethoprim/sulfamethoxazole (TMP/SMX), and less commonly ivermectin, are also used in resistant cases-although treatment of lice represents an off-label use of these agents. Hipolito and colleagues8 recommend that dual therapy with 1% permethrin and oral TMP/SMX be used-and reserved-for patients who have experienced multiple treatment failures or in whom resistance is suspected.

Nonpharmacological approaches. Nonpharmacological approaches and home remedies-such as covering the scalp with petroleum jelly, olive oil, mayonnaise, vinegar, or other products-deserve a mention because parents often try these measures. Although they have little associated risk, they are not particularly effective.1,9 Lebwohl and colleagues1 explain that trying to suffocate lice with occlusion therapy cannot work because lice do not have air sacs and can survive for prolonged periods without air. Manually removing nits by combing after applying an anti-lice product usually is an effective means of getting rid of lice, but it is not necessary to prevent reinfestation.10 Head shaving will cause lice to leave, since shaving eliminates their home (the hair); however, this approach is not acceptable to most parents or children. In any event, before any drastic hairstyle changes or further treatments are undertaken, the reason the lice won’t leave must be determined.



1. Lebwohl M, Clark L, Levitt J. Therapy for head lice based on life cycle, resistance, and safety considerations. Pediatrics. 2007;119:965-974.
2. Frankowski BL, Weiner LB; Committee on School Health and Committee on Infectious Diseases; American Academy of Pediatrics. Head lice. Pediatrics. 2002;110:638-643.
3. Bailey AM, Prociv P. Persistent head lice following multiple treatments: evidence for insecticide resistance in Pediculus humanus capitis. Australas J Dermatol. 2000;41:250-254.
4. Hansen RC. Overview: the state of head lice management and control. Am J Manag Care. 2004; 10(9 suppl):S260-S263.
5. American Academy of Pediatrics. Pediculosis capitis. In: Pickering LK, Baker CJ, Kimberlin DW, Long SS, eds. Red Book: 2009 Report of the Committee on Infectious Diseases. 28th ed. Elk Grove Village, IL: American Academy of Pediatrics; 2009: 495-497.
6. Maunder JW. Lice and scabies. Myths and reality. Dermatol Clin. 1998;16:843-845.
7. American Academy of Pediatrics. Children in out-of-home child care. In: Pickering LK, Baker CJ, Kimberlin DW, Long SS, eds. Red Book: 2009 Report of the Committee on Infectious Diseases. 28th ed. Elk Grove Village, IL: American Academy of Pediatrics; 2009:129.
8. Hipolito RB, Mallorca FG, Zuniga-Macaraig ZO, et al. Head lice infestation: single drug versus combination therapy with one percent permethrin and trimethoprim/sulfamethoxazole. Pediatrics. 2001; 107:E30.
9. Takano-Lee M, Edman JD, Mullens BA, Clark JM. Home remedies to control head lice: assessment of home remedies to control the human head louse, Pediculus humanus capitis (Anoplura: Pediculidae). J Pediatr Nurs. 2004;19:393-398.
10. American Academy of Pediatrics. School health. In: Pickering LK, Baker CJ, Kimberlin DW, Long SS, eds. Red Book: 2009 Report of the Committee on Infectious Diseases. 28th ed. Elk Grove Village, IL: American Academy of Pediatrics; 2009:145.

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