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Does mayonnaise really kill head lice?

Missy says…I used two lice treatments on my hair. Today I am trying to condition my hair because it is completely dry and still a little itching. I researched and mayonnaise is supposed to kill lice plus condition hair….is this true??

The Beauty Brains respond:

Can mayonnaise kill head lice? Missy, Missy, Missy. That is ridiculous! It only takes a quick search of the scientific literature to prove that using mayonnaise on lice is just a load of bull… wait a minute… There’s a study in a peer-reviewed scientific journal that suggests this might actually work? Hold the presses!

The science of suffocation

Here’s the deal. While it’s common to use pesticide-like materials to kill lice there is a newfound interest in alternative methods because lice are becoming resistant to some of the pesticides. Fortunately it turns out that lice can be killed by a method that is more physical than chemical: if you plug up the little breathing ports on their body you can actually suffocate them. The problem with this approach of course is that you have to really make sure you smother them in something. Just putting on a shower cap (like some people) suggest isn’t going to cut it.

According to the journal Pediatrics a product called DSP lotion (which stands for Dry-On, Suffocation-Based Pediculicide) uses an emulsion consisting primarily of fatty alcohols to coat the little buggers. The lotion is applied wet and then blown dry with a hair dryer. The resulting film plugs the spiracles and the lice suffocate. In the published testing the treatment was 96% effective.

Is mayo murderous?

So what about mayonnaise as a murder weapon for lice? Mayonnaise, as the cooks in our audience already know, consists of egg whites, vinegar and lemon juice. Since egg whites do have film forming properties it’s not inconceivable that they could “shrink wrap” the lice just like the DSP product. I presume to make it work properly you would also have to blow dry it on the hair to maximize the shrink wrapping effect. Fortunately, there’s nothing in the mayo that will dry out your hair.

Of course it’s also possible the level of solids in mayonnaise is NOT high enough to be effective. But, it’s certainly a cheap alternative and there’s no risk in giving it a try. If you’re more desperate for surefire solutions you can track down this DSP product.

The Beauty Brains bottom-line

Sometimes even the most seemingly outlandish statements needs to be evaluated down to see if there’s any  potential truth to it. In this case it turns out that using mayonnaise on your hair might just take care of lice after all.

Comments on this entry are closed.

  • Firoza June 26, 2014, 8:53 am

    Actually, mayonnaise contains egg yolks not whites. I suspect that the yolks, when mixed with vinegar do have film forming properties — witness the tempera masterpieces from early renaissance period, which survive even to this day in good condition. Even egg yolk on its own tends to dry in to a film, but it also tends to crack easily, so on their own, yolks an even poorer form of insecticide than mayonnaise.

    • admin June 26, 2014, 9:23 am

      Either that was a typo or Randy is a really bad cook!

  • Eileen June 26, 2014, 10:33 am

    You forgot the most abundant ingredient in mayonnaise–oil! A standard mayonnaise recipe will contain approximately a cup of oil (canola, corn, olive, etc.) for every egg. It’s the very slow addition of oil as the other ingredients are whisked that creates that creamy consistency.

    • Randy Schueller June 26, 2014, 12:05 pm

      Eileen and Firoza: Thanks for catching my mayo mistake. I guess if I knew foods as well as I do cosmetic formulations we’d be the “Cooking Craniums” instead of the Beauty Brains.

      • Firoza June 26, 2014, 12:25 pm

        Hey, cooking skills or no cooking skills, you guys are doing a great job. You probably do not realise how much money you (and your book) have saved me and your other readers, but it is quite a lot, so Thank You.

  • Jami June 26, 2014, 6:48 pm

    Mmm – I’ll stick with the 50/50 solution of rubbing alcohol and shampoo for killing lice. Sure, it dries out the hair, but I never had an infestation growing up because mom always did this. And she’d just keep shampooing my hair until the bottle was empty.

  • Mrs X October 5, 2014, 9:35 am

    Is it true that mayonnaise is by definition a hydrolyzed egg protein and oil. Hydrolysis consist of adding an acid such as vinegar or lemon juice, water along with a protein such as egg, correct? Thus mayonnaise consisting of whole eggs or yolks, water, lemon juice and or vinegar will by definition break down the proteins in the eggs. Is it not true then that mayonnaise is a good HYDROLYZED protein treatment and hot oil treatment in one?

    • admin October 5, 2014, 1:30 pm

      It’s not as good as products formulated for that purpose.