Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at June 28, 2016

Pediculosis or lice infestations have occurred throughout human history and references to this condition are a part of many cultures. Terms in everyday language such as ‘nit-picking’ and ‘lousy’ originate from pediculosis. Today pediculosis is a familiar problem among children in particular; it affects children ages 3 to 11 more than any other demographic in the United States. It is a highly preventable and highly treatable condition without lasting or severe health consequences.


Definition & Facts

Pediculosis is the infestation of lice, a type of insect, in the hair of the human body, or in clothing. Lice are ectoparasites that live on the human body. Lice live off of human blood which they acquire after piercing an individual’s skin and injecting saliva which can cause an allergic reaction triggering itchiness or pruritus. Pediculosis can be spread for as long as the eggs and the lice stay alive on the individual that is infected or in their clothing. There are several different types of lice including:

Pediculosis can involve an infestation of the lice eggs, nymphs, and adults. Lice only crawl and cannot fly. A female can lay 3 to 6 eggs a day. The eggs, also known as nits, are white in color and less than 1 millimeter long. When the lice hatch from the nits after about 8 to 9 days, they are called nymphs and they will reach their maturity in approximately 9 to 12 days and only live as an adult for around 30 days.

Symptoms & Complaints

The first sign that an individual has an infestation is scratching in the area of the body where lice like to feed. Head lice cause itching at the back of the head or around an individual’s ear. Pediculosis may cause a person to feel irritated and may cause sleep problems.

Itching in the genital area might be an indication of pubic lice. The scratching can be bad enough that it leads to a secondary bacterial infection in some of these areas. Symptoms can take up to four weeks or even longer to manifest in such a way that an individual would notice the infestation.


Pediculosis is spread from person-to-person by close physical contact. It is uncommon though possible for lice to spread through sharing brushes, hats, and clothes or from sitting on a piece of furniture that a person with the infestation had just been in contact with.

Head lice is the most common kind of pediculosis. Primarily affecting children, head lice is spread by head-to-head contact in most cases. This can occur at slumber parties, at summer camps, and in the classroom. Head lice affects girls more than boys.

Pubic lice primarily occurs among sexually active people. Because lice do not jump or fly, close contact such as that during sex usually must occur for pubic lice to be transmitted from one person to another, though other means of transmitting them is also possible. Trying on undergarments that are infested which may be more of an issue with used or vintage clothing could cause a pubic lice infestation.

Body lice are more common in crowded, unsanitary situations where people are changing their clothes infrequently and not washing them. The conditions that produce this tend to be overcrowded areas stricken with war, poverty, or homelessness.

Diagnosis & Tests

There aren't any specific lab tests for pediculosis. A doctor will make a diagnosis based on physical observations of the lice on the patient's hair or body part. Lice is commonly diagnosed during lice check-ups at public schools.

Treatment & Therapy

Pediculosis is mainly treated with medicated shampoos or cream rinses that contain pyrethrin, piperonyl butoxide, and permethrin. There are over-the-counter-treatments that contain pyrethrins or permethrin but products that contain antiparasitic medications, lindane or malathion can only be obtained with a doctor’s prescription.

Infants, small children, pregnant or nursing women, elderly people, individuals with easily irritated skin or sores, those that weigh less than 110 pounds and individuals with HIV or seizure disorders should not use a lindane based shampoo. It is important to repeat the treatment 7 to 10 days later to make sure no eggs have survived. It is also helpful to get special combs that remove nits from hair.

For someone with body lice, all infested clothing and linen should be washed with hot water and a hot dryer. Furniture should also be vacuumed, steam-cleaned, and possibly treated with chemicals that specifically target lice.

Prevention & Prophylaxis

Regular inspections for lice at schools, institutions, and nursing homes can help prevent pediculosis outbreaks, though only students with live lice are recommended to be excluded from school until treatment has completed. The Centers for Disease Control and Prevention do not advocate a no-nit policy that requires students be removed from school immediately when a nit has been discovered during a school inspection because such nits are unlikely to hatch and produce crawling lice that could be easily transmitted.

Additional preventive measures include avoiding physical contact with individuals that are infested with lice. During any infestation, children should be taught to not share clothing that was stacked in a common area. All individuals that are exposed should be examined and treated to stop the spread.

Education can also help to reduce infestations in schools. Education on how lice live and how they are transmitted from person to person may empower students and parents with the knowledge they need to treat and prevent infestations.

Any sexual partners that an individual with pubic lice has had from the previous month should be treated. Sex should then be avoided until the individual with pubic lice has been treated successfully. Those with public lice may be at higher risk for other sexually transmitted diseases and should be tested.

Failure to use or follow through with a lice treatment can cause the transmission of many types of lice infestations. Therefore, making sure to follow all of the detailed instructions on how best to apply and time the treatments and medications is necessary in not only treating pediculosis but preventing its spread.