Over New Year's weekend I had the pleasure of hiking in a slightly warmer climate. Being the consistent dermatologist that I am, I was wearing long pants and long-sleeved protective sun gear. For the most part, this also protected me from mosquito bites, although at some point I rolled my pants up to cross a stream and forgot to roll them back down. I ended up with about 20 itchy bites below my knees. Besides being physically uncomfortable, I considered this a professional defeat as I am usually on top of this sort of thing! At any rate, this is a question that I answer for my patients often, regarding what is safe as far as protection from bugs.
Much as with the sun, physical barriers are your first layer of defense. Mosquito netting over your sleep site, long pants, and long-sleeved shirts are the most useful and long-lasting solutions. However, sometimes it's just too hot to wear these things or maybe the bugs are just particularly aggressive, and there are still the exposed areas such as faces and hands to consider.
Permethrin is in the pyrethroid family of medications, which are organic compounds similar to natural pyrethrins produced by the Chrysanthemum family of plants. Permethrin is reasonably natural and is recognized as safe in pregnant women and in infants over 2 months of age. Most importantly, you can apply it to your *clothes* (because why put more chemicals on your skin than you have to, even organic ones?) and there is no staining and no smell. If I am traveling somewhere that I expect mosquitoes, I use the Sawyer's brand in the yellow spray bottle (I order it on amazon.) and spray my long pants and long-sleeved shirts with it. They dry quickly and then I can pack them. It will last on the clothes up to 6 washings. You can also spray tents and bed nets with permethrin. It also wards off ticks and chiggers. Another bonus is that you can spray the inside of your suitcase with it--let it dry and pack the case and travel without fear of bed bugs coming home with you!
Picaridin is my third choice for protection. It is a synthetic molecule that mimics the active compound in black pepper (piperidine). You can apply 20% picaridin directly to your skin. It comes as a cream rather than a spray. It is almost colorless and odorless and in 20% concentrations (but not the lower concentrations), it has been reported to be as effective as DEET without the irritation associated with DEET. In places where I would fear serious problems from a mosquito bite: malaria, Zika virus, dengue fever (because do I really want to catch something the locals call "break bone fever"?), I go ahead and use picaridin cream on my hands and face or any other clothing gaps. If a bite would just be annoying, rather than dangerous, then instead of the picaridin I'll use the more natural insect repellents, such as oil of lemon eucalyptus for my exposed skin. (I buy the REI brand for that but there are many others available.)
The infamous DEET, or diethyltoluamide, is probably best avoided as reports of toxicity are rare but very real. Plus, it is oily, stains clothing, and hovers in a volatile cloud around you so that you can smell it and even taste it during your otherwise awesome outdoor picnic. It is also a strong solvent and can dissolve plastics and synthetic fabrics, including your outdoor gear. I avoid DEET unless it is the only option available in a situation where there is a risk of contracting disease via insect bites. However, with some reasonable planning you can safely use the other options listed above.
Posted on Wed, February 1, 2017
by Heidi Gilchrist