Head lice, specifically Pediculus humanus capitis, are tiny insects that live on the human scalp and feed on blood. While these parasites do not transmit disease, their presence requires prompt and systematic action for complete eradication. Successfully removing these “bugs” involves accurate identification, careful treatment, and thorough environmental cleanup. This guide provides clear, medically accepted steps to resolve an infestation.
Recognizing Head Lice and Nits
Confirming the presence of head lice requires understanding the appearance of both the adult insects and their eggs, known as nits. An adult louse is a six-legged insect, roughly the size of a sesame seed, ranging from tan to grayish-white. They are most frequently found close to the scalp, particularly behind the ears and at the nape of the neck, where they find warmth and darkness.
The most common sign of infestation is the presence of nits, which are the lice eggs glued firmly to the hair shaft. Nits are small, oval, and teardrop-shaped, typically white, yellow, or light brown before hatching. Unlike dandruff, nits are cemented to the hair and require pressure to slide along the strand, while dandruff flakes off easily. Nits are generally laid within a quarter-inch of the scalp, indicating an active infestation. The intense itching associated with lice is an allergic reaction to the louse saliva injected during feeding.
Step-by-Step Treatment Options
Eradication relies on a multi-pronged approach combining chemical treatments and meticulous mechanical removal.
Over-the-Counter Treatments
Over-the-counter (OTC) products are the first line of defense and typically contain pyrethroid-based insecticides, such as permethrin. These compounds work by disrupting the louse’s nervous system.
When using these products, follow the package directions precisely, which usually involves applying the product to dry hair, allowing it to sit, and then rinsing. Since many OTC treatments do not effectively kill all unhatched eggs (nits), a second application is necessary. This re-treatment is recommended 9 to 10 days later to kill newly hatched lice before they can mature and lay more eggs. A challenge is the rise of resistance, as many louse populations have developed gene mutations that reduce the effectiveness of pyrethroids.
Mechanical Removal (Wet-Combing)
Regardless of the chemical treatment used, mechanical removal using a fine-toothed nit comb is necessary for successful elimination. This process, known as wet-combing, is highly effective when performed with a generous amount of hair conditioner applied to wet hair. The conditioner helps stun the live lice, preventing them from gripping the hair, and allows the comb to glide smoothly.
Starting at the scalp, draw the comb through the hair from root to tip. After each pass, wipe the comb onto a paper towel or rinse it in water to remove captured lice or nits. Work through the hair section by section until the entire head has been combed thoroughly. This wet-combing procedure must be repeated every three to four days for a minimum of two weeks until no live lice have been found for three consecutive sessions.
Prescription Options
If OTC products and diligent wet-combing fail, a healthcare provider may prescribe stronger medications. These prescription treatments work through different mechanisms to kill the lice. Malathion lotion is an organophosphate that is both pediculicidal and partially ovicidal, meaning it kills live lice and some eggs. However, it is highly flammable and typically reserved for those six years of age and older.
Another option is benzyl alcohol lotion, which works non-chemically by suffocating the lice by obstructing their breathing apparatus. Since benzyl alcohol is not ovicidal, a second treatment seven days later is required to address newly hatched nymphs. Ivermectin lotion is a single-application treatment that kills lice and prevents nymphs from surviving, often eliminating the need for nit-combing.
Cleaning the Environment and Preventing Reinfestation
Head lice are human parasites and cannot survive long without a host for feeding, typically dying within 24 to 48 hours off the head. Therefore, extensive or costly house-wide cleaning is not necessary. Focus on items that have been in contact with the infested person’s head in the 48 hours prior to treatment.
Bedding, towels, and clothing should be machine washed using hot water, set to a temperature of at least 130°F, and then dried using the high heat cycle. Items that are not washable, such as stuffed animals or certain coats, can be sealed in a plastic bag for two weeks. This process eliminates any lice or nits due to lack of a blood meal.
Vacuuming carpets and upholstered furniture is recommended to remove any stray hairs with attached nits or fallen lice, but chemical sprays are unnecessary and potentially hazardous. Preventing future infestations centers on simple behavioral changes. This includes teaching family members to avoid head-to-head contact, especially during play or sports, and to not share personal items like hats, scarves, or combs. Routine weekly head checks with a fine-toothed comb allow for early detection, which is the best way to minimize the length and severity of any future outbreak.