1942 by Marjory Collins
Clothes dryers have long been used as a method for killing lice that are infesting clothing, headgear, bedding, stuffed animals, and other items that can be washed and thrown into a dryer. Now many people are beginning to experiment with using heat from hair styling equipment, such as hair dryers, hair curlers, and straightening irons, to kill lice and nits (lice eggs). In 2006, researchers decided to study this method scientifically. They tried several different methods of applying heat to hair: bonnet-style hair dryers, handheld blow dryers, wall-mounted blow dryers like those used in public restrooms (but with a hose attached to use in applying heat to hair), a heat application device called a LouseBuster (invented by the scientists in order to do the study), and a LouseBuster used in combination with a lice comb (blowing hot air onto the comb while it was used to comb through hair). The handheld and wall-mounted blow dryers worked very well for killing nits, but not as well for killing living lice. The LouseBuster killed between 76 and 80 percent of living lice, along with most nits. That does not sound like enough, but it is not necessary to kill each and every louse and nit—all you need to do is kill enough of them to prevent them from breeding. Another option, though, is to use another treatment for head lice, but add hot air as a supplement to the treatment while combing nits out.
As heat’s role in killing lice becomes more well known, many people are experimenting with killing lice using hair curlers and hair straightening irons. However, the researchers who did the 2006 study say that it is not heat alone, but heat combined with blowing air that kills lice. Based on that description, it sounds as though a blow dryer would work best, but researchers cautioned that blow dryers were effective for killing nits, but only killed about half of live lice on the head. They did find, however, that blow dryers were more effective the more carefully they were used—if the hair was divided into more sections, more lice were killed. For example, dividing the hair into 20 sections instead of ten caused more than twice as many lice to be killed.
Although hot air may be effective for killing lice and nits, it is also advisable to remove any remaining nits from hair, clothing, and bedding, just in case some of those nits are still viable.
Using Heat to Get Rid of Head Lice
- Choose a time of day when you have 30-35 minutes to spare.
- Brush or comb the hair first to eliminate tangles.
- Use hair clips to divide the hair into 20 sections.
- Hold dryer still for 30 seconds while heating one side of the section, and then hold the dryer still again for another 30 seconds to heat the other side of the section. Do this for each section of hair.
- Repeat daily as necessary until all lice are gone.
Why It Works
The combination of heat and blowing air can cause lice to become dessicated, or dried out. Researchers say that a constant flow of dry air is much more important than heat in aiding the dessication process.
Before you begin any system of treatment for lice, be sure of your diagnosis. Head lice, in particular, are often misdiagnosed. Ordinary dandruff is frequently mistaken by parents for nits, or lice eggs. One way to tell the difference is to notice whether they fall out of the hair easily, or stick to the hair shaft. Nits will stick to the hair and are difficult to remove.
It is easy to inflict a burn while using a hair dryer or other heating device. Be sure to hold the blow dryer a safe distance from the head of the person being treated. The researchers who did the 2006 study noted that their homemade LouseBuster actually used much cooler air than the average hair blower—the air flow was more critical than the heat for dessicating the lice and nits.