Insect Repellants

Jun 30, 2011

By Trevor Shewfelt, Pharmacist at the Dauphin Clinic Pharmacy

Lady Gaga is pantless in Paris. Apparently that was the perfect sentence. It was perfect if you wanted Google to notice your article on the internet and have lots of people find it in a Google search. Then Google changed its algorithm, and it isnt perfect anymore. That reminds me of other perfect sentences. The quick brown fox jumped over the lazy dog. I had to type that one many times in typing class because it had every letter in the alphabet in it. The rain in Spain falls mainly on the plain. That was the perfect sentence for Eliza Doolittle in My Fair Lady to work on her accent and pronunciation. Maybe perfect sentences are in the eye of the beholder. Or maybe nothing is quite perfect. Lets look at summer. Could be the perfect season, right? There might not be a fly in the ointment, but there is another insidious insect that summer brings.

It has been a cool, wet spring. Until recently, the mosquitoes were slow coming out. However, the heat has arrived! Dauphin has its BBQs out and its tank tops on! Unfortunately, standing water and warmth is just what the little vampires were waiting for. If you go outside, Manitobas unofficial bird is going to get you.

What should you know in the battle with the droning blood suckers we love to hate? Try to reduce the amount of time you spend outdoors around sunset and sunrise. These are the peak hours for mosquito activity. Make sure the screens on your doors and windows dont have rips or tears. Remove standing water from your property. That includes emptying childrens wading pools, cleaning your eavestroughs, regularly emptying bird baths, and ensuring rain barrels are covered with a mosquito screen.

People often ask me if it is safe to use a bug spray with DEET in it or if they should use something more natural, like citronella. My usual answer is that DEET has been shown to keep mosquitoes away from people and citronella doesnt have the evidence. Although DEET has some potential problems, if used properly it is relatively safe. After researching this article, I can now say Health Canada is looking into whether citronella is safe. It appears that there are chemical components in citronella that may be cancer causing if applied to the skin. It seems like Health Canada isnt concerned enough to pull citronella products from the market yet. Health Canada may even deem citronella safe after the review, but it is interesting that they are looking at a natural product.

Onto the product I use. I like bug sprays with DEET in them. So how do you use them safely? First remember that DEET is NOT recommended for children under 6 months of age. You can use 1 spray per day of DEET of 10% or less on children aged 6 months to 2 years if it is absolutely necessary. You can use DEET of 10% or less on children aged 2 to 12 years not more than 3 times per day. Over the age of 12 you can use DEET up to 30%.

What do the different percentages mean? The higher the percentage the more DEET could get absorbed through the skin, but the more mosquito repelling power the bug spray has. Here is what Health Canada says: repellents with concentration of DEET of 30% will protect you from mosquitoes for approximately 6 hours, DEET 15% for ~5 hours, DEET 10% for ~3 hours, and DEET 5% for ~2 hours.

New repellants with 30% DEET and higher will no longer be registered for sale in Canada because of fears of the health risks with long term exposure. However, since there have been no actual reports of problems, existing products with 30% DEET in them still be allowed to be sold. Health Canada hopes to phase out the 30% DEET products eventually.

Whenever you talk about mosquitoes, someone asks about West Nile Virus. West Nile Virus was first identified in Africa in 1937. It spread to Europe and it was first reported in North America in New York City in 1999. Since then it has spread to most parts of the US and Canada. The first known human case of West Nile Virus (WNV) in Manitoba was in July of 2003. West Nile Virus is carried by mosquitoes. That means that the mosquito bites an infected animal (often a bird), picks up WNV and then bites the human and gives them WNV. The number of human cases of WNV varies year to year. According to Manitoba Health the number went from 143 in 2003 up to 587 in 2007 and down to 12 in 2008.

What are the symptoms of WNV? Most people who become infected with the virus do not become ill, and so wont report an illness to their doctor. This is the most common outcome. The other two outcomes are West Nile Fever and West Nile Neurological Syndrome. West Nile Fever has flu like symptoms such as fever, headache, fatigue and body aches. West Nile Fever is usually considered mild and resolves on its own. West Nile Neurological Syndrome is much more rare and is more serious. The neurological syndrome can include encephalitis, an inflammation of the lining of the brain. Encephalitis can have serious complications including paralysis, confusion, coma or death. Anyone experiencing symptoms like persistent high fever, muscle weakness and headache should seek medical attention.

Summer is really close to being the perfect season. It is so short, we can put up with a few mosquitoes. One of the things Im doing this summer is visiting my hometown in Eastern Manitoba. Do you think: Lady Gaga is pantless in Pinawa? could be a perfect sentence?

For more information visit:

Health Canadas Insect Repellant Page:

Manitoba Healths WNV page:

As always if you have any questions or concerns about these or other products, ask your pharmacist.

The information in this article is intended as a helpful guide only. It is not intended to be used as a substitute for professional advice. If you have any questions about your medications and what is right for you see your doctor, pharmacist or other health care professional.

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