Treatment of Head Lice
C. H. Hong, MD, FRCPC
An estimated 1 in 10 children in Canada will be affected by a lice infestation this year and it is more common worldwide than the common cold. Head lice infestations, i.e., Pediculosis humanus capitis, are the most common type, which can occur worldwide and affect people of all ages and socioeconomic groups. Lice are wingless, bloodsucking insects. They are difficult to see because they are about the size of a sesame seed and they adapt to take on the color of their surroundings.
Clinical Manifestations and Diagnosis
Head lice are typically confined to the scalp, and while itching is the main symptom of lice infestation, the lice themselves are not itchy and the bites are generally painless. Itching is caused by the body’s immune reaction to the saliva injected into the skin at the time of the blood meal. Redness and scaling may also be seen in the scalp as can small, itchy bumps on the posterior neck. Enlargement of lymph glands in the neck can be occasionally seen.
Diagnosis can be made ONLY by identification of a living louse. Nits or eggs are often empty shells and not an indication of an active infestation. Nits are also often mistaken for dandruff, sand or dirt, or dried hair gel.
Myths and Facts
Myths about head lice are abundant and belief in these myths is often why treatments are not used properly and why people believe their lice treatment has failed. Some common myths include:
There are many proposed “natural” and alternative cures for treating head lice including various oils (e.g., tea tree oil), petroleum jelly, peanut butter, and mayonnaise; however, the effectiveness of most are dubious. There are no clinical studies to demonstrate effectiveness of these agents and many are messy and difficult to use. Most patients will need to be treated with a commercial product designed to kill lice. Most of these are available over-the-counter and work by attacking the central nervous system of the louse. No pediculicide is 100% ovicidal. In order to achieve maximum effectiveness, the pediculicide needs to be applied to dry or nearly dry hair. It should be saturated to allow sufficient pediculicide to penetrate lice and nits and left on for the entire recommended time.
Permethrin 1% cream rinse (Nix®/Kwellada-P®)
Synergized pyrethrins (R & C® shampoo)
Lindane shampoo 1%
Regardless of the type of treatment recommended, patients should be encouraged to use a nit comb (i.e., a fine toothed metal comb such as the LiceMeister® comb), on wet hair to manually remove the nits, which can become cemented to the hair shafts. Treated patients should also be monitored for reinfestation.
Following treatment, all clothing should be machine laundered and dried in the dryer (hot cycle). In addition, bed linens, towels, stuffed animals, and any headgear should be cleaned. Clothing that cannot be washed can be dry cleaned or sealed in a bag for 2 weeks. Combs and brushes can be covered in the pediculicide and then washed in hot water for 20 minutes; alternatively they can be soaked in a disinfectant solution (e.g., 2% Lysol® for 1 hour). All interior areas should also be cleaned and vacuumed to remove any shed hairs.
Reasons for Failure of Treatment
Head lice are a common and embarrassing problem with many good treatments. Patients should be appropriately counseled to minimize spread of infestation and then advised on appropriate topical treatments. For further information about lice and lice eradication as well as counseling tips and patient material go to www.SkinPharmacies.ca/CE.
*This article was adapted from Hong CH. Treatment of Head Lice. Skin Therapy Letter – Pharmacist Edition 1(2):4-5 (2006 Sep- Oct).
All content ©2005
Skin Care Guide.com Ltd. All Rights Reserved.