Parents and schools tend to have a strong reaction to finding out a child has head lice. I hear “burn down the house” often given as a recommendation for dealing with lice. Head lice aren’t a health hazard or a sign of dirtiness or poor hygiene. They are, though, one of the most common causes of school absenteeism. Despite not causing any actual medical problems, those little bugs cause a great deal of anxiety among parents and schools. Grab a drink, y’all, because there is a lot to talk about.
Head lice can be identified by seeing the actual bugs crawling in the hair, although it is often difficult to see them. An adult louse is about the size of a sesame seed and has six legs. More commonly what you will see are nits, which are lice eggs. Nits looks like tiny tan or yellow dots on the hair shaft close to the scalp (to keep them warm). They look a lot like dandruff, but unlike dandruff, they can’t be brushed off, because they are stuck to the hair. Nits hatch 1-2 weeks after they are laid, leaving behind a white shell that is still attached to the hair shaft. This can be the easiest stage to see, as the hair is growing a little longer, but they are still close to the scalp. Lice bite the scalp and feed on a blood meal, which causes itching. Your child (or you) scratching the scalp may be your first indication that something is going on (although you are probably scratching your head right now…I sure am). If not treated, the cycle of egg-laying, hatching, and maturing to adulthood repeats about every 3 weeks.
Lice don’t hop or jump. They only crawl, so they only spread by very close contact. Lice can only live for 1 day away from a head, and eggs can’t hatch at temperatures below those of a human body, so transmission of lice through objects is very uncommon. Lice seen on combs and brushes are usually dead. The most effective way to avoid spreading lice is to avoid head to head contact.
Note: When rinsing lice treatments out of the hair, the head should be over a sink, to limit body exposure to the medication, and the water should be warm and not hot.
Over the Counter Treatments
Permethrin (available as Nix) is available as a 1% lotion. It is less allergenic than pyrethrins and has a low toxicity in mammals. Hair should be shampooed with nonconditioning shampoo and towel dried. The permethrin lotion is then applied to damp hair and left in place for 10 minutes and then rinsed off. It leaves a residue that is intended to kill any eggs not killed with the initial application. Repeat application is recommended at day 9, although an alternate schedule has repeat applications at days 7 and 13-15. There is some permethrin resistance, but its prevalence is unknown.
Pyrethrins (manufactured from natural chrysanthemum extract) are formulated with piperonyl butoxide (available as Rid). Pyrethrins are neurotoxic to lice and have low toxicity to mammals, although they should be avoided by anyone who is allergic to chrysanthemums. Available as a shampoo or a mousse, they are applied to dry hair and left on for 10 minutes before rinsing. They do not kill eggs, which do not have a nervous system, so treatment needs to be repeated on the same schedule as for permethrins. There is quite a bit of resistance to pyrethrins, although it varies from community to community.
Malathion (Ovide) is available in the US as a 0.5% lotion. The lotion is applied to dry hair, left to air dry, and then rinsed off after 8-10 hours. It is very toxic to eggs, so often, one application is all that is needed, although it should be used again if live lice are seen at 7 days. The lotion has a high alcohol content, making it flammable, so hair should be allowed to air dry, rather than using a blow dryer, curling iron, or flat iron, and no one should smoke around it. There is a lot of resistance to malathion in the UK, but the formulation in the US has other lice-toxic compounds in it, which may reduce resistance.
Benzyl alcohol 5% (Ulesfia) kills lice by smothering them. It is approved for babies as young as 6 months. It is applied to dry hair from the scalp to the ends in a sufficient amount to saturate the hair and left in place for 10 minutes. Because it doesn’t kill the eggs, it needs to be repeated on the same schedule as permethrin.
Spinosad (Natroba) is also approved for children as young as 6 months. It is derived through natural fermentation from soil bacterium Saccharopolyspora spinosa. It should be applied on dry hair saturating the scalp and working outward to the tips rinsing 10 minutes after application. It works both by killing lice and by killing eggs. If live lice are seen after 7 days, a repeat application can be done.
Ivermectin (Sklice) is available as 0.5% lotion. It causes paralysis and death of lice. It should be applied to dry hair and scalp and rinsed after 10 minutes. Sklice is very expensive, although the company (Sanofi Pasteur) often has coupons available on their website. Ivermectin is the same medication that is used to deworm animals. Another, much cheaper option is to buy horse dewormer, which is available online and at local farms stores. I found it a the Wilco in Bend for $5. Be sure you are buying straight ivermectin without anything else in it. Horse ivermectin is 1.87%, so you need to dilute it. Dial the dose for 250 lb (it makes sense if you look at it) and squirt that amount into 1/4 cup conditioner and apply this to the hair. One tube of horse ivermectin has 5 doses in it.
There are lots of anecdotes about petroleum jelly, mayonaise, butter, olive oil, or herbal oils for lice, but none of these have been evaluated for effectiveness. Multiple essential oils have been recommended for lice treatment (notably tea tree oil), but these have not been evaluated for effectiveness or safety.
An uncontrolled, nonrandomized (in other words, not robust) study of Cetaphil cleanser showed a 96% cure rate. The cleanser is applied to the hair, dried with a blow dryer, left on overnight, and rinsed out the next morning. This treatment is repeated once a week for 3 weeks.
Combing with a lice comb to remove dead lice and nits should be done on wet hair after treatment. Lice combs can be purchased separately but often come in kits with over the counter lice treatments. Electric combs are available which claim to kill live lice and nits as they comb through the hair, but these have not been studied for effectiveness.
Things that have been in contact with the lice-infested head in the previous 24-48 hours are the only ones that need to be cleaned. Vacuuming is sufficient for carpets and furniture. Pillows only need pillowcases changed. Washing, soaking, or drying items at greater than 130 degrees F will kill lice and nits. Items that cannot be washing can be bagged in plastic for 2 weeks. Insecticide sprays and significant cleaning are not necessary.
Children with nits will not necessarily be children with active lice infestation, so routine screening at school is not recommended. Given that a kid with live lice has likely been infested for at least a month, sending home from school is not recommended. No-nit policies are discouraged by both the American Academy of Pediatrics and the National Association of School Nurses. If your child’s school is trying to exclude him or her over head lice, contact your pediatrician. We are trying to get these policies stopped.
That’s a lot about lice. If you have questions or concerns about lice and want to talk to your child’s doctor, please call first. We are happy to talk, but we don’t necessarily need to see you in the office (scratch, scratch).
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A look at some topics in breastfeeding, medicine, and kids health.