Head Lice: Scratching Below the Surface
If the mere mention of head lice gets you scratching your head, perhaps a dose of facts will ease your fears. UR Medicine Dermatologist Dr. Mary Gail Mercurio explains what it is, how to find it, and how to beat it.
Health Matters: Let’s start with the basics. What is head lice and how do I know if I have it?
Mercurio: Head lice, or pediculosis capitis, is a common condition caused by infestation of the scalp with the head louse (plural = lice). Although a diagnosis of head lice can wreak havoc in a household or school/day care setting, it is not considered a health hazard because lice do not spread disease. Head lice aren’t picky about their victims. They are found around the world, mainly on children of all socioeconomic backgrounds. While some people can have lice infestations with no symptoms, for most, the tell-tale sign is itching. Itching can affect the scalp, neck, and ears, and is caused by an allergic reaction to the louse saliva, which is injected under the skin as the louse feeds. Sometimes, scratching can spread bacteria, which leads to infection and enlarged lymph nodes of the neck and around the ears.
Detecting lice is simple. It’s done by examining the scalp to check for the sesame-seed-sized insects in motion. A female louse lives about 30 days, during which she can lay hundreds of eggs. The eggs are called nits and they hatch after eight days. Combing the hair with a very fine-toothed metal comb can confirm the problem and also help remove lice and nits. It is a tedious process and tougher with thicker, longer hair.
Health Matters: So, I found it. Now what do I do?
Mercurio: The most popular, effective treatments are over-the-counter topical insecticides like permethrin or pyrethrin. They come in cream-rise form, which you apply to the scalp, leave on for 10 minutes, then wash and rinse away. This regimen is repeated in 7 to 11 days, to target any eggs that survived and hatched after the first treatment. Other treatment options include malathion, spinosad, benzyl alcohol and ivermectin. Treatments vary based on any known patterns of resistance, drug adverse effects, and what a person will tolerate best. Head-louse resistance to topical insecticides is a growing concern and varies geographically, but if treatment fails, it’s most often because a person doesn’t properly follow treatment instructions or they continue to have contact with others who have it but go untreated.
Health Matters: The idea of putting pesticides on my head is scary. Aren’t there natural remedies that I can use?
Mercurio: Herbal and home remedies are popular and based on the idea that you can suffocate the lice with oil or silicone-based materials applied to the scalp. However, there’s little science to support whether this is safe or effective. Also, it’s important to recognize that a person can have an allergic reaction to something that is considered “natural.” Some people even try shaving the scalp to get rid of lice, though most are reluctant to do something that extreme. And combing for nits can certainly help in conjunction with a topical treatment, but is not likely to eliminate the problem on its own. It’s important to recognize that products on the market have undergone extensive testing long before reaching the pharmacy’s shelves. Following instructions carefully is key to using these products safely and effectively.
Health Matters: How contagious is head lice? And how can I keep it from spreading?
Mercurio: Direct hair-to-hair contact with the head of someone who is infested is the No. 1 way to transmit head lice. So, a covered scalp covered or tightly bound hair style may offer more protection than free-flowing locks. If one person has it, everyone living in the same household should be checked. (Look closely around the top of the neck and ears, which are the most common locations for nits). Only those who share bedding with someone confirmed to have head lice should be treated as a precaution.
Lice can live off the scalp for only a couple of days at most, and there’s debate about how much or how little inanimate objects contribute to the spread of head lice. You should avoid sharing hats, towels, brushes or combs during active infestations. Clothing items should be washed in hot water and dried on a high-heat setting. Items that can’t be washed or dry cleaned can be sealed in plastic bags for a few weeks. And while avoiding upholstered furniture for several days is a good idea, there’s no need to throw it away. Contrary to urban legend, lice neither jump nor fly. And it’s fine to continue cuddling your pets as there is no evidence that lice is spread by dogs and cats.
Health Matters: Anything else we should know?
Mercurio: Finding nits in your child's scalp does not necessarily mean there is active infestation. Nits are stubborn and can hang around for months after successful treatment. They tenaciously cement themselves to the hair shaft and are difficult to dislodge.
As with any health concerns, it’s always wise to consult your health care provider with your specific questions and for advice suited to your individual situation.
Mary Gail Mercurio, M.D., is a professor of Dermatology and Obstetrics and Gynecology at URMC, caring for patients at UR Medicine’s Strong Memorial Hospital. She has special interest in skin and hair disorders in women.