Insect Repellant Patches

This has been a particularly bad year for mosquitoes here in Alberta. Our cool and damp spring and summer have produced perfect conditions for eggs to hatch and mosquito larvae to thrive in numerous pools of standing water throughout the bush and settled areas. The result has been high concentrations of adult mosquitoes of various species vying for access to any exposed skin that might provide them a blood meal. If you spend any time outdoors, you quickly learn to spray yourself liberally with repellant, preferably with a high concentration of DEET (N,N-Diethyl-meta-toluamide)—the active ingredient in most commercial repellants.

DEET is very effective as it has been determined that mosquitoes and other biting insects definitely dislike its odor and will avoid it (the popular belief that it prevents the insects from detecting CO2 is wrong). When used in concentrations of 30% (maximum allowed in Canada) it can last on the skin and clothing for three to six hours (10% or lower concentrations are recommended for children 2 to 12 years of age) depending on activity and amount of sweat produced.

However, DEET does have its drawbacks. It is a solvent and can dissolve some plastics and synthetic fabrics. As I have learned, it can pit the plastic screens on watches or other such devices, making them difficult to read. It can also play hell with the plastic handles on things like fishing reels after you’ve used your hands to spread the repellant around. In a few rare cases (1 in 100 million people) it has been known to cause seizures, which could be related to the fact that DEET is known to interfere with certain nervous system enzymes if present in sufficient concentrations (i.e., don’t breath it in or leave it on your skin for longer than recommended). As a result, many people don’t want to use it, and instead look for more “natural” repellants.

Insect Defend Patch

Insect repellant patches are convenient to use but such use must be planned.

One such natural repellant that has been developed over the last few years is the insect repellant skin patch. This patch is applied to the bare skin, much like a nicotine patch used to quit smoking. Over an extended period of time a dose of vitamin B1 (Thiamine) is continuously passed from the patch through the skin to the blood stream. The B1 apparently causes the body to produce a scent that deters biting insects. The patch supposedly can provide protection from 24 to up to 36 hours.

Why not just take vitamin B1 pills? Apparently much of the vitamin taken through the digestive system is metabolized and that taken through the skin from the patch enters the blood stream much more quickly and intact.

I have to admit that I attract mosquitoes. I figure I must emit some kind of signal that says I’m a prime meal because if there are mosquitoes around they will find me. That’s why I succumbed to a sales pitch and purchased a pack (5 patches) of Omezone’s Insect Defend Patch that was “on sale” for $7.19 Cdn at a local outdoor store. That’s a pretty substantial price when compared to a can of DEET insect repellant that can be used a considerably longer period of time. However, it might be worth it if the patch does its job and is less of a health hazard.

The patch on an arm.

The patch easily adheres to the skin and can be hid behind clothing.

Following the instructions on the pack, I slapped a patch on my upper arm. I first shaved the hair off where the patch was to go to prevent hardship when I took it off. One drawback to the patch is that it takes about two hours before you see any effects. So, you have to plan its use. I applied mine in the morning about 2 hours before I was going to take my bi-daily jog. As I stated earlier, the mosquitoes have been especially prolific this year and a couple of species are very aggressive, even attacking my bare legs while I run. I usually don’t use repellant to run but this year it has become part of the ritual. This particular morning I did not spray the repellant to see if the patch would do the job. To my surprise, it did to a certain extent. Mosquitoes flew around but none landed while I was moving. When I returned from my jog and did some stretches in the yard, one lone mosquito did attempt to bite my calf before succumbing to the slap of my hand. Others attempted to land on my skin but flew away. I spent the rest of the day splitting firewood and again although mosquitoes flew around me only some actually landed. Most of those flew away but a few did attempt to bite.

The following day I still had the patch on to see how it worked after 24 hours. I found it to be less effective than the previous day. Also I did begin to notice an odor. A body odor is one of the side-effects mentioned in some of the reviews I’ve read about the patch (e.g., — scroll down to the comments where the real information is). For me, the odor reminds me of that coming from a multi-vitamin tablet bottle, so is probably the thiamin coming through my sweat. It was not offensive either to me or my family but it was noticeable. A shower eliminated it until I starting sweating again. As well, I smelled the odor in my clothing until it was washed.

I waited a couple of days before trying the next patch. Again, it was on a hot day I spent outside including jogging. This time the patch didn’t seem to work as well as it had the previous time. I did see mosquitoes attempt to land on my skin but veer away at the last moment. Others, however, came straight in and attempted to bite. I had a similar experience with a third patch I tried a few days later.

Conclusion: for me the patch works to a point but is not 100% effective. However, one should keep in mind that people’s physiologies differ. What works for some might not for others. (For example, some people detect an odor from using the patch, others do not.)

Dining with Company or Alone?

One thing I have noticed (as have others) is that while wearing the patch and sitting with a group of people, I would not be bothered by mosquitoes who were visiting the others (who hadn’t put on repellant). When I was the only one in the immediate area, at least some of the mosquitoes did bite. So, I’m thinking the thiamin does deter mosquitoes but not when they are especially hungry and you are the only choice. DEET is much more effective in these conditions.

Will I try it again? Probably. We are making a trip to East Africa this fall, and I will most likely wear the patch as a backup. Malaria is an issue in these countries, and we will be taking all precautions to prevent contracting the disease, including liberal use of DEET-based repellants and prophylactic drugs. The patch could very well be part of that arsenal.

However, for use around the house, the cost of the patch ($1.50 +/- Cdn each) is pretty dear when compared to other repellants. DEET repellants are much more convenient to use and at least for me are more effective. On the other hand, if you have a concern about using DEET products and are serious about finding alternatives, the patch might be something to try.

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About Don Meredith

I am a writer and biologist living in Alberta, Canada. I wrote a monthly column for the Alberta Outdoorsmen magazine, and have published articles for several other magazines.
This entry was posted in Country Living, Fishing, Product Reviews and tagged , , , , , , , . Bookmark the permalink.

One Response to Insect Repellant Patches

  1. Anonymous says:

    I appreciate your comments about your experience with the patch. The mosquito’s here in Chicago, Illinois are particularly obnoxious this year, so I’ll give the patch a try.
    Thank You,
    Mike Styles

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