HEAD LICE

By Trevor Shewfelt, Pharmacist at the Dauphin Clinic Pharmacy

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The information in this article is intended as a helpful guide only. It is not intended to be used as a substitute for professional advice. If you have any questions about your medications and what is right for you see your doctor, pharmacist or other health care professional.

My then five year old daughter came home from kintergarten in the fall with a pamphlet about head lice. My wife and I asked if her teacher was trying to tell her something. She said no that everyone in her class got the pamphlet. So we felt better as parents, and that is one of the reasons we usually start getting lice questions at the pharmacy in September and October. Head lice doesn’t just happen at the beginning of the school year, though. It can happen at any time.

What are lice? Head lice are parasites that live in humans’ hair. The scientific name for them is Pediculus Humanus, and they are wingless insects with six legs. They are tiny grey insects that are the size of a pinhead and can barely be seen with the naked eye. They multiply very quickly. Females lay 7 to 10 oval and whitish eggs called nits every day. Seven to ten days later, the nits hatch and are called nymphs. The nymphs mature in 10-14 days and lay more eggs. So the whole life-cycle is about 30 days.

So how is head lice transmitted? Lice are transmitted two main ways. Lice can be transmitted directly by close contact from one infested scalp to another (i.e. touching heads together). They can be transmitted indirectly by sharing personal articles that come in contact with the head (e. brushes, hats, etc). Louse transfer has been found to be optimal when hairs are relatively stationary and parallel, suggesting that louse transmission is more likely to occur while children are at rest (e.g. taking a nap together), than during periods of vigorous play (e.g. wrestling on the ground). Children from 3 to 10 years old are the most affected age group. However, anyone can get lice, regardless of sex, race, age, hair length or socio-economic status. There are a lot of myths and misconceptions about head lice. Head lice is not a sign that your child’s hair is dirty. Lice actually prefer clean hair. Lice cannot fly and lice cannot jump. Lice can only survive on humans; therefore you cannot get lice simply by being in contact with pets, sand, grass, trees or plants.

What are the symptoms of having lice? The most common symptom is persistent itching, especially around the ears and back of the scalp. There can be small sores, or small scabs on the person’s scalp or neck. If these sores get infected, there can be pus. How do you recognize head lice? First you should see nits (the eggs) attached to the base of the hair shafts on the warmer parts of the scalp (the back and sides). The egg or nit is oval and glued to the hair. Nits are laid close to the scalp for warmth, usually around the ears and the nape of the neck. Live nits are brownish in color, and dead ones are whitish. Dandruff, hair casts, and hair spray globules are sometimes mistaken for nits. You can tell that they are not nits because they can be easily removed, while nits are firmly cemented to the hair and can only be removed with the fingernails or a fine toothed nit comb. Nits found more than 1.0 cm from the scalp have grown out with the hair and have either hatched or are dead. The nymph is a miniature replica of the adult louse, but it cannot reproduce. It goes through three stages before becoming an adult. And then there is the adult. It is approximately 1-2 mm in length. It is elongated in shape, greyish, has six claw like legs, and no wings. It avoids light by staying away from the top of the head and is usually found around the ears and nape of the neck.

The main product used to treat head lice is permethrin (one of the brand names is Nix). It actually sticks around for up to ten days after use to kill any more lice that hatch. It is generally the product of first choice because is very good at killing the eggs, it has low toxicity and it sticks around for about 10 days. Although it is not absolutely necessary to do a repeat application, it is often recommended that one uses the permethrin again in 7 to 10 days. There is a similar product to permethrin on the market and it contains natural pyrethrins (one of the brand names is R&C Shampoo). It is not as good as permethrin at killing the eggs. It doesn’t hang around after application. It must be reapplied in 7 to 10 days for it to be effective. Both permethrin and pyrthrins can cause allergic reactions in ragweed or chrysanthemum sensitive individuals. There are older products that contain lindane available as well. Lindane is not as good as permethrin at killing eggs. It doesn’t stick around so you must do a second application in 7-10 days for it to be effective. About 10% of the lindane actually goes into the rest of your body and it can accumulate with repeated exposure. It can cause seizures and other neurologic disorders so lindane is not my favorite product.

Because of the perceived lack of effectiveness of some of the commercially available products, the Dauphin Clinic Pharmacy has developed an all natural oil lice treatment. It coats the hair and suffocates the lice. It can be used as an alternative to the commercially available products.

There is a new product on the market now for lice called Resultz. It contains isopropyl myristate. This is different that the Nix like products. The permethrin in Nix attacks the nervous system of the louse. Isopropyl myristate is more like a soap. It dissolves the waxy outer coating on the louse and the louse dehydrates. The down side to Resultz is it does not kill the nits or eggs in the hair. So you absolutely need to do the second treatment in one week. On the positive side, there is no documented resistance to Resultz. Back in the 1980’s permethrin like products killed 100% of lice. I have seen estimates now that in places it kills more like 28% of the lice. It can be hard to tell if these treatment failures are due to poor application technique, but resistance to permetherin is probably real. There were small studies where Resultz killed more lice than permetherin. I don’t know if I am ready to say it is definitely better than permetherin yet, but it is nice to have another tool against lice.

Some non-medication measures should be taken when a family member gets lice. Combs and brushes should be soaked in alcohol or Lysol for one hour; or they can be soaked in water 65oC or hotter for 10 minutes. Bedding, towels, and clothing should be washed in hot water and dried in a dryer for 20 minutes to an hour. It is actually the heat from the dryer that kills the lice. Other items may be dry-cleaned or stored in a sealed plastic bag for 2 weeks. Lice can’t live away from human contact for very long, so the two weeks allows the eggs to hatch and the new lice to die. Some people have even stored these plastic bags full of teddy-bears etc. in the freezer. Vacuuming of carpets and furniture is also a good idea.

The eggs, or nits, are very difficult and tedious to remove because they are cemented onto hairs. Hold the hair at its end and comb towards the scalp with a fine toothed comb or tweezers. Vinegar and water in a 1:1 ratio can be used to help dissolve the cement that holds the nits onto the hair. Although tedious, nit removal is very important because even permetherin only kills about 70% of the eggs.

As always if you have any questions or concerns about these products, ask your pharmacist.