Head Lice: OTC Pediculicides
It is the time of year again that parents long for and children dread?it is time to go back to school! Many parents, however, also dread this time of year for another reason?it is head lice (Pediculus capitis) season.
Unfortunately, there is a great deal of misinformation about head lice that causes unnecessary fears and contributes to the social stigma of lice infestations. The good news for parents is that having head lice is not a sign of poor hygiene, and infestations can be successfully treated when parents and caregivers know the facts about headlice treatment and fully comply with instructions. Pediculosis infestations are very common, with as many as 6 million to 12 million cases worldwide each year. Most of these cases are in children between the ages of 3 and 10 years old, and family members may become infested as well. We know that pediculosis is a common condition, but what treatment options exist to eradicate it?
How Are Head Lice Treated?
Before considering treatment options, it is important to realize that head lice rarely, if ever, cause direct harm (other than annoyance). Yet, secondary bacterial infections, impetigo, and local adenopathy may occur if the scalp is lacerated from vigorous scratching.
A head-lice infestation is not a medical or public health problem, and perhaps the most significant concern associated with head lice is the use or overuse of potentially toxic agents to treat pediculosis. Head-lice infestations should be treated only if live lice or nits within 1/4 inch of the scalp are properly identified.
Regardless of the choice of treatment, certain guidelines are recommended. The treatment process involves 2 steps: (1) treating the infested person(s) (Table 1); and (2) preventing reinfestation by cleaning the house (Table 2).
The safest method of eradicating head lice is by using the simple but time-consuming method of manual removal of the lice and their nits, especially in children under 2 years of age. Parents should be instructed to use a comb and to part the hair in sections, using the fingernails to remove lice and nits. This process may be repeated daily until all nits and lice are removed. OTC products are available to loosen the cement-like substance that binds nits to the hair shaft, but these products have not been shown to provide clinical benefit.
If manual removal is ineffective, or if another treatment method is desired, many OTC pediculicides are available in a variety of formulations such as creams, lotions, and shampoos.
Before discussing individual agents used in treating head lice, it is important to remember that, currently, no product is 100% ovicidal. Therefore, some nits often survive and may cause reinfestation. Pediculicide resistance has been reported with some OTC products, although the prevalence of this problem is unknown. Treatment failure often may be due to misdiagnosis, misidentification, or noncompliance with the treatment regimen.
All topical pediculicides should be rinsed from the hair over a sink, using cool water, to minimize product absorption due to vasodilation. Reactions to these topical agents may consist of itching or a mild burning sensation, and they may be treated with topical corticosteroids and oral antihistamines.
Pyrethrins with Piperonyl Butoxide
These products (eg, Pronto Plus, RID), derived from natural extracts of the chrysanthemum flower, usually are sold in shampoo form and are applied to dry hair for a period of 10 minutes prior to rinsing. A second treatment 7 to 10 days after the initial treatment is required, because 20% to 30% of the nits remain viable after treatment. Although rare, allergic reactions are possible in patients known to be allergic to chrysanthemums. Toxicity potential is minimal.
This type of product (eg, Nix) is a synthetic py-rethroid derivative and is currently the treatment of choice for pediculosis. Permethrin 1% has even less toxicity potential than natural pyrethrins, and it does not potentiate allergic reactions in persons sensitive to chrysanthemum. The cream-rinse shampoo is applied to damp hair after shampooing with a nonconditioning regular shampoo. It is left on for 10 minutes and is rinsed (Table 1). Retreatment in 7 to 10 days is indicated only if live lice are seen at this time, because the product has a residual effect of exterminating the 20% to 30% of nits that survive the initial application.
Several nonpesticide OTC products are available for the treatment of head lice. As natural products, they are not required to meet FDA guidelines for safety and efficacy. These mixtures of essential oils, salts, or other natural substances have not been conclusively shown to be efficacious.
Here are some final points to remember when counseling patients: do not use extra amounts of lice medication, and do not mix lice products. Using the same lice medication more than twice without good results may indicate the need for a different treatment or a prescription product.
When patients are properly educated about head lice, they will be better prepared to cope with this common childhood experience. Although children may always dread the annual return to school each fall, parents who are properly informed about head lice can rest easy and stop worrying?at least about head lice!
The opinions expressed in this article are those of the author and do not necessarily reflect the views of the US Public Health Service or the Federal Bureau of Prisons.
Dr. Newman is a senior assistant pharmacy officer with the US Public Health Service/ Federal Bureau of Prisons. He is currently assigned to the Springfield US Medical Center for Federal Prisoners, Springfield, MO.