Is Mosquito Repellent Safe?

Is Mosquito Repellent Safe?

Sure it is!  I'll tell you what's not safe: mosquito borne diseases.

We tend to think of mosquito borne diseases as "someone else's problem."  Malaria kills two million children under five every year, but most of the deaths are in the developing world.  West Nile Virus had a lot of hype in those early years, but most of the hype has settled down and we didn't all die from it, so how big a deal could it be?

Mosquitos are a remarkably efficient transmitter of diseases.  They suck the blood from one warm-blooded creature, and then dribble some of it back into their next victim. It's like you're getting backwash, but it's the blood of a complete stranger. 

At the same time, the mosquito itself doesn't get sick - not only does its digestive system break down the viruses before they can attack the mosquito, but most of the viruses wouldn't affect mosquitoes anyway.

There is an entire complex of encephalitis diseases which are spread by mosquitoes in America.  These include West Nile Virus, the showy news-worthy newcomer on the scene.  There are two reasons that West Nile Virus isn't as big a problem as the news outlets said it would be:

1.    People heeded the warnings, and started being more rigorous about applying mosquito repellent.  If you don't get bitten, you won't get the disease.
2.    The news outlets do a terrible job of science reporting, and act like every damned thing is The End Of The World.

However, the CDC also warns of St. Louis Encephalitis, Equine Encephalitis, and several others.  Encephalitis is serious, and can easily be fatal.  It's not good to have your brain squeezed by an inflammation!

On the other side of the equation is mosquito repellent.  There is a lot of concern these days over topically applied chemicals, and rightfully so.  From the parabens in our shampoos to the sulfates in our toothpaste, we are being bathed in chemicals whose long term effects are unknown and poorly understood.

That being said, DEET is one of the most widely applied chemicals on the market today, and there is a lot of bogus and useless information out there about DEET alternatives.  DEET is a repellent, not an insecticide, and it works as basically a cloaking device that hides you from mosquitoes.  DEET works phenomenally well, but "more is better" isn't necessarily true.  The Canadian government has found that DEET's effectiveness tops out at about a 50% concentration, which is one reason why Canada has moved to cap DEET concentrations at 30%.

There are mosquito repellents which do not contain DEET, of course.  Although Canadian field trials have shown that they are not as effective for as long:

  • 10% DEET concentration (which is recommended for children): 2-4 hours
  • Soybean oil, 2% concentration, topically applied: 90 minutes
  • p-menthane-3,8-diol 10% concentration (OFF! Botanicals Lotion Insect Repellent): 90 minutes
  • Citronella oil, 10% concentration, topically applied: 20 minutes
  • Lavender oil, 6% concentration, topically applied: Less than 30 minutes


Additionally, the CDC and the EPA both have tested a slew of alternative repellents, and are recommending Oil of Lemon Eucalyptus or PMD (found in Repel Lemon Eucalyptus), and IR3535 or ethyl ester.

I will say, having grown up in Alaska where we know a thing or two about mosquitoes, that citronella candles are worse than useless.  They smell awfully nice, though!

Photo credit: Flickr/James Jordan