Ask the Pharmacist

Q) My son came home from school with an itchy head. I checked his hair and I think it is lice. I tried a bottle of Nix but it didn’t seem to work. How can I be sure it is lice and how is it best treated?

A) Lice have long been the bane of parents despite the fact that an infestation does not lead to disease or harm one’s health in any serious way. They are an equal opportunity nuisance threatening all socioeconomic classes which hopefully helps lay to rest the myth that their presence is an indicator of poor hygiene.

They are commonly found in school aged children between the ages of 5 and 11 due to the manner in which they are transmitted. Lice are incapable of jumping, flying or hitching a ride on your pet. But they are more than capable of going from one head to another when there is direct contact or when an infected hat or brush is borrowed, habits that are far more common in younger children than in adults or their older peers.

While lice can only live up to 24 hours away from a human in typical environments, their eggs (known as nits) can survive for up to 10 days away from its host. The best way to diagnose head lice is to see an adult louse in one’s hair, not an easy task given their size and the speed at which they are capable of moving. The adult louse is approximately 1-3mm in length and appears as though it has been flattened. It has six clawed legs which it uses to grasp onto hair shafts. It usually has a white- grey colouring unless it has just feasted on its host in which case it temporarily changes to a red- brown colour. A louse lives for 16 days and can lay up to 150 eggs. These eggs are firmly attached to the hair shaft close to the scalp and hatch somewhere in the range of 6 to 10 days. Within 8 days of hatching, the louse is a fully functioning adult capable of laying eggs of its own or transferring to another host if given the opportunity. Spotting eggs/ nits does not necessarily mean you have an active infection since they can persist on the hair shaft after successfully treating lice.

The best way to spot a live louse is to apply conditioner liberally to dry hair and comb out any tangles one quadrant at a time starting from the root and combing out. After combing, wipe the conditioner off of the comb and spread it out to identify nits or lice. Nits on a shaft can be distinguished from dandruff or hair care products by the degree of difficulty required to remove it from the hair shaft. Nits are firmly glued on making them quite difficult to dislodge.

As for treatment, traditionally the gold standard has been the pyrethroids such as Nix which is an inexpensive and safe treatment. Unfortunately, it is no longer all that effective. It is estimated that only 28 to 55% who use a product like Nix along with careful combing have success in eradicating the lice. This is believed to be due to rapidly developing resistance among lice to Nix’ neurotoxic effects.

The good news is that there are two newer products that appear to work very well and due to the method they use to kill the louse, resistance is unlikely to be an issue in the future.

Resultz is applied onto dry hair (30-60ml for short hair & 90-120ml for long hair), massaged into the scalp and left on for 10 minutes before being rinsed off. The hair should then be thoroughly combed with a very fine tooth comb to remove dead lice and the nits. Treatment should be repeated in 7 days to kill any hatched nits before they are old enough to lay their own eggs. Resultz has a good safety profile and can be used in children two years of age and older. There is currently no safety data on its use during pregnancy or breast feeding.

The other recommended product is called Nyda. It works by essentially asphyxiating the lice and due to this method of action resistance is not expected to develop. Nyda should be sprayed onto dry hair and left on for 30 minutes. After this, it should be combed throughout the hair using a lice comb and then subsequently left on the hair for another 8 hours before it can be washed out. Treatment with Nyda should be repeated in 8 to 10 days.

While there are no head-to-head studies between the two products, Nyda’s raw numbers seem to indicate it might be the more effective killer as well as having the advantage of being able to kill the nits. It too is only recommended in children older than two and should not be used during pregnancy or while breast feeding due to a lack of safety data.

Regrettably both of these products are much more expensive than Nix with Nyda being the most expensive option by a considerable margin. No matter which product is chosen, the time consuming combing of the hair to remove nits should be done at least every 3-4 days with special attention paid to areas such as behind the ears and the nape of the neck. Soaking the hair with vinegar 30 to 60 minutes before serves to loosen the wax that holds the nits in place making them easier to comb out. All clothing and bedding should be washed in hot water or stored in plastic bags for at least two weeks. Floors and furniture should be vacuumed but spraying with an insecticide is not recommended.

There are no two ways about it. Lice are a major hassle but with proper treatment they should be only a temporary drain on your sanity. For more information about this or any other health related questions, contact your pharmacist.