What Actually Kills Lice? And Kills Them Fast?


Kids are always coming down with something! Colds, flus, fevers, ear infections and head lice can all take your children out of school, out of daycare and out of commission. Whether you’ve just gotten that letter from the school nurse or you found little creepy-crawlers on their scalp as you were tucking them into bed, you probably want to know how to kill lice FAST.

Unlike the flu or an ear infection, lice can’t be treated with a pill or a shot. Even medications and treatments designed for lice have been known to fail, and even effective treatments may need to be repeated for weeks to fully take care of the infestation.

An adult female head louse may lay 10 eggs every day. These eggs are cemented to the shaft of the hair near the scalp with a kind of “glue”, making them very difficult to see and remove. They may look like dandruff, so they sometimes evade detection for a time.

About a week after the nits are laid, they’ll start to hatch. These lice babies, called nymphs, are very small, about the size of a pinhead. They grow, shed their exoskeletons and grow some more, until they become adults in about a week.

Once they’re fully grown, these lice may continue living in your hair and laying eggs for about a month. Since the adults are only about the size of a sesame seed, they may remain undetected for quite some time. A single pair of adult lice could turn into an infestation of more than 100 in as little as a few weeks.

Chemicals to Kill Lice

Medicated shampoos with a pediculicide can help to kill lice. These shampoos are available by prescription or over the counter, and they may contain ingredients like malathion, permethrin, or lindane.

Malathion is commonly used as an agricultural pesticide. Shampoos with malathion usually require that the chemical remains on the scalp for 8-12 hours, and malathion is flammable, so it’s not recommended for use with blow dryers or curling irons. Certain people will have sensitivity to malathion, and it can be toxic to humans and to local waterways when it is rinsed out. In the United States, this generally requires a prescription.

Permethrin is one of the safest pediculicides available to kill lice. It dissipates rapidly in the environment, and most humans can tolerate a moderate dose with few ill effects. However, some people may have an acute sensitivity to permethrin, and it may not kill the nits.

Lindane is primarily used as a second-line defense when milder medications have failed. California has banned the substance due to its environmental impact, and other states have presented bills to restrict its use to prescriptions only. It’s a neurotoxin with many reported side effects, and it’s not recommended for use in young children or pregnant women. In the United States, this chemical normally requires a prescription.

It’s important to note that chemical treatments won’t kill all lice. Lice have been reported to show resistance to chemical treatments, and most studies indicate that these chemicals are effective less than 90% of the time. Chemicals to kill lice may not be effective on treating their eggs, so these options will usually require multiple uses in order to fully treat the infestation.

Enzymes to Kill Lice

Certain types of naturally occurring enzymes can be used in a medicated shampoo or spray. These enzymes are generally safer and less toxic than chemicals, and they work to kill lice by destroying the exoskeleton (shell) of the insect. While they are usually less harmful to the environment and safer for children, they often require multiple uses and are ineffective at killing the eggs.

Oils to Kill Lice

While chemicals work by poisoning the lice, oils work through suffocation. Some traditional home remedies may call for mayonnaise or olive oil, and newer products may contain dimethicone, a silicone-based oil. They’re a safe alternative, even for young children, but they can be messy, as they require the oil to be spread thickly on the scalp and hair and left for a period of time. They can be difficult to rinse out, and they may not always be as effective on nits, so they may require multiple treatments.

Electricity to Kill Lice

Poison. Dismemberment. Suffocation. When it comes to killing lice, we’ll try almost anything! Here’s where electricity comes to the rescue.

When you run an electric lice comb through the hair, it detects and zaps the louse. Once it’s dead or stunned, the comb can be used to remove the louse from the hair. Like suffocation, electricity works on all lice, even those that are resistant to chemical treatments. It can be used even on very young children, and it doesn’t require a long period of soaking, so it can be over in as little as 20 minutes.

Electric lice combs, like the RobiComb®, are a fast way to kill lice, but they don’t always get the nits. It’s best to use the comb daily for ten days, but some families may use the comb once a week as a preventative measure for infestations. With no chemicals and little fuss, it’s easy to continue using it to prevent future infestations, especially if there’s an outbreak in your child’s school or daycare.


Goodbye, Lice!

Head lice seldom cause medical problems, but they’re incredibly annoying and highly contagious. When there’s an outbreak of lice, it’s important that you kill them FAST, before they spread, breed and infest even more people. Fortunately, there are a number of safe, effective ways to kill lice quickly.

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