The Best Mosquito Repellents: Which One’s Right for You?

by James Hubbard, MD, MPH

Last week, we talked about how to prevent mosquito bites. Today, we’ll delve into the vast array of mosquito repellents to help you decide which option is best for you.

All four of the main repellents mentioned in this post work. Some work better on some people than others, so finding the best repellent for you can be just a trial and error thing. But with each one, there are some tips you’ll want to consider.

First, the main tip …

Try Not to Poison Yourself

No man-made chemical or natural repellent that works is completely safe. All can be potentially toxic in some situations. To decrease that risk, always follow directions on the product’s label, and beware of:

  • Over-applying or applying more frequently than recommended.
  • Using sunscreen over the repellent, which can increase absorption—and therefore the amount of chemicals that get into the body. Topicals that contain a sunscreen and repellent pose a problem in that you need to apply sunscreen more often than repellent for protection.

As I like to quote from the founder of toxicology, Paracelsus:

“All things are poison, and nothing is without poison: The dose alone makes a thing not poison.”

Interpretation: “The dose makes the poison.”

You can further limit the dose you need by following these tips:

  • If you’re putting the repellent directly onto your skin, apply it only to exposed skin, except around the eyes, nose, and mouth. The forehead is a little iffy since contaminated sweat could get in the eyes and cause irritation. In fact, other than maybe the cheeks and ears, I’d just skip the face. Consider wearing a hat, sweatband, scarf, or cap instead.
  • Remember that children are at more risk of toxicity due to their size and developing bodies. Don’t let little ones apply repellent to themselves, and keep it off their hands since hands tend to end up in the mouth. After the child returns indoors, wash the treated skin or bathe the child. Not a bad idea for adults either.

Other than DEET, most mosquito repellents have not been studied enough for us to be able to say with certainty whether they are safe, especially for small children. So the directions and restrictions err on the side of caution. With the lack of studies, plus the variety of environments and skins, length of effectiveness is difficult to determine, and predictions can be all over the place.

All of the following repellents repel ticks, chiggers, and other insects in addition to mosquitoes.

DEET

N,N-Diethyl-meta-toluamide, aka DEET, is probably the most controversial repellant. It has also been studied more than any and has been deemed overall safe if used as directed. I was surprised to see that even the Environmental Working Group, which came down so adamantly against certain sunscreens, states DEET isn’t perfect but is a much better alternative than getting a mosquito-borne disease, though the EWG does recommend against products with over 30 percent DEET.

Tips:

  • Strengths: DEET comes in concentrations of 10 to 100 percent. No increased effectiveness has been found in using concentrations over 50 percent. And 50 percent or more can cause severe skin irritation.
  • Longevity: A DEET application of 30 percent is effective for six to 12 hours. A 10 percent concentration is effective for about two hours.
  • Warnings*: The FDA recommends not using over a 30 percent concentration in children and not using DEET at all on babies 2 months of age or under. I’d say the 30 percent is a good maximum for adults also. For pregnant women, there have been no serious problems found if used as directed.
  • Clothing friendliness: DEET can damage any material other than cotton, wool, or nylon.

Picaridin

Picaridin is a chemical repellent whose effectiveness lasts about as long as DEET. At this point it is considered safer than DEET, but picaridin has not been studied nearly as long as DEET. Always use as directed. Precautions are the same as with DEET.*

Oil of Lemon Eucalyptus

Oil of lemon eucalyptus is an extract from the lemon eucalyptus (Corymbia citriodora) leaves that’s diluted and used as an effective mosquito repellent. Don’t get this mixed up with other oils on the market with similar sounding names. Some repellents also contain a synthetic version of the extract’s most active ingredient, PMD.

Tips:

  • Longevity: A 30 percent concentration of oil of lemon eucalyptus protects against mosquitoes for around two hours.
  • Warnings*: Don’t use on children under 3 years of age or of you’re pregnant or nursing.
  • Clothing friendliness: Oil of lemon eucalyptus can damage materials that are not cotton, wool, or nylon.
  • Other insects: Oil of lemon eucalyptus may be more effective against ticks than DEET.

IR3535

IR3535, or 3-[N-Butyl-N- acetyl]-aminopropionic acid, ethyl ester, is found in some Avon Skin So Soft products and in Coleman SkinSmart DEET-Free.

Tips:

  • Strengths: IR3535 is available in concentrations from 7.5 to 20 percent.
  • Warnings*: Although there is potential for toxicity, when used as directed, it is deemed very safe and can be used when pregnant.
  • Clothing friendliness: IR3535 has the potential to damage the same clothing materials as DEET and oil of lemon eucalyptus.

The original Skin So Soft, which is still available, has no IR3535. However some people do still use this product to protect themselves from mosquitoes and ticks. Studies have found it much less effective than the other repellents, but if it works for you, great.

Permethrin

Permethrin repellents can be sprayed on the exterior of clothes.

Tips:

  • Longevity: The chemical’s effectiveness lasts for six washes or so. You can even buy clothes that have been pretreated with permethrin; their effectiveness can last for 60 washings.
  • Warnings*: When sprayed onto clothes, permethrin is deemed safe for all ages, but don’t spray directly on skin. Its most active ingredient, pyrethrum, which is also sold in repellents, comes from chrysanthemums and is touted as even safer. But I couldn’t find any studies that found that it works as well as permethrin.

Other Options

Other topical products, such as soybean oil, catnip, mint, and citronella, may help, but usually for less than an hour at best. If it works for you and is deemed safe, that’s really all that matters.

My Mosquito Repelling Plans

For me, my main mosquito defense will be barriers, such as screens, loose clothes, socks, and a hat. If I’m hiking, I’ll tuck my pants in my boots and use some of that duct tape I suggest in my book Duct Tape 911. (Taping the gap between the boots and the tucked-in pants will help protect against ticks and chiggers.)

All topicals have their worries. I think I’ll start with Avon Original Skin So Soft this year, hoping it will work. If it doesn’t, I’ll try IR3535 but will have picaridin handy just in case. I’ll spray my clothes with permethrin.

For my 6-year-old grandson, I’d choose the same overall plan. For babies, I’d first try netting—preferably the kind that comes with permethrin.

Now that’s just me. As I said in the introduction, different repellents work better for different people. You may have to experiment to find the best repellent for you. That also may mean researching whether a mosquito-borne disease is active in your area and, if one is, what type of mosquito is carrying it. Different repellents work better on some types of mosquitoes than others.

As for the multiple other natural creams, lotions, and oils? If they work for you and are safe, why not.

I’ve told you what mosquito repellents I think are best for me. What about you?

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*These are select warnings, not exhaustive ones. Read the product’s label for more complete information.

 

 

Photo: “Repellents” by Flickr/Fairfax County, shared via CC BY-ND 2.0.