How to Kill Lice

how to kill lice

Until Licefreee!® non-toxic head lice treatments hit store shelves in 1999, the go-to treatments (called pediculicides) were those that contain the chemical pesticides: permethrin & pyrethrum. These chemical pesticides are neurotoxins, whose function is to attack the nervous system of lice to kill them.

Resistance to Traditional Lice Treatments

Unfortunately, chemical pesticides aren’t likely to affect head lice eggs (called nits) due to their tough exterior shell, and/or because they likely have not developed a nervous system at the time of treatment. Therefore, a thorough combing to remove the eggs is a must. If just one egg is missed, it is possible for a reinfestation to occur. Additionally, a study by the Journal of Medical Entomology* has shown that head lice in 48 states across the U.S. have reportedly developed a resistance to these treatments, commonly referred to now as “super lice”. Also note: For children or adults with allergies to ragweed, pyrethrum can cause an allergic reaction.

Non-toxic or Natural Over-The-Counter Lice Treatments

Most consumers choose treatments sold over-the-counter (OTC). While some of these natural or non-toxic options are actually treatments for head lice infestation, a significant number of these products are simply lubricants to help aid the comb-out process, or they are repellents. Of the products that are treatments, Licefreee! is the first of its kind, using Natrum muriaticum (or, sodium chloride a.k.a. salt) to effectively kill lice and their eggs. So how does Licefreee! kill lice? Sodium chloride desiccates (dehydrates) head lice and their eggs; eggs are no exception as Licefreee! is able to penetrate through their shells. Because the treatment kills lice and nits through a mechanical action rather than a chemical action (think permethrins & pyrethrums), they are unlikely to build a resistance to the treatment.

Home Remedies

What about those home remedies? We’ve heard it all: mayonnaise, mouthwash, olive oil, coconut oil, avocado, the list goes on. These are the options parents choose when either a.) other treatments have failed, or b.) they are in search of a head lice treatment that doesn’t contain potentially harmful chemical pesticides. There are a couple of reasons why these methods of “smothering” aren’t likely to work.

First, head lice have a series of breathing “holes” along both sides of their abdomen. Lice are able to control these holes and close them off when an attempt to smother them is made. They can “hold their breath” like this for several hours!

Next, the eggs. Trying to smother the nits is an impossible task, as they are protected in their shells. Like the aforementioned treatments, the eggs would have to be combed out entirely to avoid a reinfestation.

Combing Only

Then there’s the good old-fashioned nit picking. This method of head lice “treatment” certainly can eradicate the problem. The only trouble with this technique is the length of time it takes to complete this process. Combing should be done in 1-inch sections to ensure all lice and eggs are removed. For children with long, thick hair, this can take hours and can be quite challenging with young children who have trouble sitting still.


There are prescription options for head lice treatments. Most are very strong chemicals and can be very expensive, as much as several hundred dollars even with insurance. In addition, they require a trip to a medical professional to prescribe them. Most consumers opt for more affordable over-the-counter options.

So, what kills lice? It’s up to you to choose the treatment right for you and your family. Now that you have information on the available options, you can make an informed decision!

Lice Clinics

There are lice removal businesses that can take care of your head lice for you. However, they can require appointments, return visits and may cost hundreds of dollars per visit.  In addition, you still have to clean your home to help prevent the spread of lice infestation throughout the household. This is why most families choose over-the-counter lice treatment options which are much more affordable and can eliminate lice quickly.

*Journal of Medical Entomology: Expansion of the Knockdown Resistance Frequency Map for Human Head Lice (Phthiraptera: Pediculidae) in the United States Using Quantitative Sequencing

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This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.