Are Sprays Labeled as ‘Lice Prevention’ Effective?

Lice-prevention products include sprays that often contain essential oils. However, many of these are based on myths instead of facts.

When it comes to head lice, there are many anecdotal claims about ingredients and products that can prevent them. Some of these include mayonnaise, vinegar, essential oils, and butter.

However, very little evidence suggests any of these substances are actually effective.

In this article, we’ll look into the products that claim to prevent lice, the research behind them, and whether they can help. We’ll also look into science-backed preventive strategies that work, so you can help protect yourself and your family against lice.

A quick search on the internet reveals thousands of spray products that claim to prevent lice. Most of these primarily contain an essential oil or a combination of oils, such as:

• tea tree
• rosemary
• lemongrass
• citronella
• eucalyptus

However, the evidence backing these ingredients for lice is minimal.

An older 2007 study compared a synthetic compound against tea tree, coconut, peppermint, and lavender oils for lice treatment. It found that, while tea tree oil did cause some repellence, the compound and the botanicals failed to prevent lice.

A 2017 study in Turkey took head lice samples from school children and tested them in Petri dishes. They put drops of essential oil extracts, including rosemary, lemon, lemongrass, and geranium, on the lice samples and took measurements for 24 hours. The researchers found that rosemary was more effective than the other oils in treating lice.

However, the limitation is that this was an in-vitro study, which means it was done in a lab rather than tested directly on humans. If you or your child has lice, rosemary oil may still not be effective enough to treat it.

Interestingly, an older 2004 study found that a topical product with slow-release citronella was more effective than a placebo at treating lice on children. However, the scientists only included 198 participants, and 95 took the placebo. The article’s abstract also doesn’t imply whether the product contained other active ingredients besides the citronella and whether it was effective at totally removing lice on its own.

Another 2016 in-vitro study found that eucalyptus could be helpful against lice. However, there have yet to be conclusive human studies and or any indication of the best topical form and at what concentration it would be effective.

This research indicates that even though some essential oil sprays could help, there’s not enough evidence to prove their effectiveness.

Based on this research, essential oil spray may not be a good choice for preventing or treating lice.

While most sprays and do-it-yourself formulations on the market contain essential oils, some products use other ingredients.

One of these is N,N-diethyl-3-methylbenzamide, commonly known as DEET. This is an active ingredient in many repellent products. However, the evidence for it is questionable.

For example, one 2007 study found that DEET did not prevent lice. The researchers argued that, while lice growth slowed, this was because of the slippery nature of DEET and oils used in the study rather than their capability to defeat and prevent lice growth.

Another option is caprylyl glycol, or octanediol. This ingredient is common in skin care products. Some sprays and products labeled as lice prevention contain a higher amount of caprylyl glycol as their active ingredient.

However, the data is minimal. A randomized, double-blind 2004 study involving 63 children between 4 and 16 years old found 1% octanediol effective at preventing lice, but the study was too small for the results to be conclusive.

Another 2004 study compared using a 2% piperonal spray versus a placebo on 105 children and adults. Piperonal is an organic compound commonly found in fragrances. The study’s results showed very little difference between the piperonal and placebo on lice.

Finally, some lice prevention products contain ethyl butylacetylaminopropionate, or IR3535, a repellent, as their main ingredient. A 2013 study tested a spray product containing IR3535 on lice and found it to be effective at killing them. However, the study was in-vitro and not on humans, and the results varied between 16% to 59% lice mortality rate after 24 hours of application.

According to the Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA) , there are ways to reduce the chance of getting lice, but it has more to do with behaviors than products.

To prevent the spread of lice, you should avoid sharing:

• Clothing and accessories that touch your hair: This includes scarves, hats, uniforms, bands, and coats.
• Toiletries and hair tools: This includes towels, brushes, and combs. If you or your child has lice, disinfect any hair tools by washing them with soap and very hot water.
• Personal belongings: Keep your belongings separate from anyone else’s until the lice infestation is completely treated.
• Bed, mattress, or pillows: Avoid sharing these items when there’s a lice infestation.

Other tips include the following:

• Machine-wash all linen or clothing with hot water and dry on high heat. If you have clothes that can’t be washed, you can dry-clean them or store them in a sealable plastic bag for 2 weeks.
• Vacuum all furniture and floors where someone with lice has been.
• Check your family for lice for several weeks after completing treatment.

There are many lice-prevention sprays available. Most of these either contain essential oils or other chemicals like DEET. However, there are not enough studies to conclude that these sprays are effective.

The best way to protect yourself and your family from lice is to apply behaviors that make it difficult for lice to grow, such as properly disinfecting hair tools and toiletries.

Last medically reviewed on April 10, 2023