Saturday, July 11, 2009

What's With Mosquito Repellent Patches?

I just saw an ad in my current Canadian Gardening magazine for a patch which claims to repel mosquitoes. Having an intense hatred for all biting insects, I was intrigued, though suspicious of its efficacy. The "OmeZone Insect Defend Patch" apparently contains thiamine (vitamin B1), which is released into your system through your skin. It starts acting within 2 hours and can deter mosquitoes for up to 36 hours, according to the ad. It is promoted as safe for children and pregnant women, which probably appeals to the people who are cautious about synthetic chemical repellents. It costs $6.95 for a pack of 5. My questions about the patch:
(1)
How does it work? I have read that it essentially makes you appear stinky to mosquitoes. A repellent odor oozes out in your sweat, though this is not apparent to other humans.

(2)
Does it work for all kinds of mosquitoes, including Culex tarsalis (spreads West Nile virus in this province), and the Aedes and Anopheles species? I can't find any published articles demonstrating its proposed effect. If it is effective, then why hasn't this been already used widely in prevention of malaria.

(3)
Why not just take oral thiamine, if this purpose is to get it into your body and into your sweat?
Stewart C. Harvey, Ph.D. recommended 100 mg of vitamin
B1 as an effective mosquito repellent in a 2002 comment to the New England Journal of Medicine (not a study or review article). The oral thiamine is certainly cheaper. One major drugstore sells thirty 100 mg tablets for $5.41. I suspect the patch format fools the general public into ignoring the fact that this is still a drug acting on your body, albeit an essential vitamin. Perhaps the manufacturer aims to make the drug more long-acting by formulating it as a transdermal patch? In that case, I'd probably rather just take a few tablets of the thiamine over the course of 36 hours.

Other reasons to use a patch:
(a) you can't take anything orally because you are unconscious or don't have a functioning gastrointestinal tract
(b) you want to avoid metabolism of the drug in the liver (which does not apply to thiamine, but commonly applies to hormones) or
(c) you want a slow steady release of the drug over time (good for narcotics, nicotine, and hormones).


(4)
Are there any good studies on humans that show that a thiamine patch is effective in repelling mosquitoes?
A search of OVID Medline with the search terms "mosquito" and "thiamine", limited to English and humans, revealed only 4 articles. Only one had an abstract (
Journal of the American Mosquito Control Association. 21(2):213-7, 2005 Jun.). It described their study, where oral B vitamin complex supplements failed to have a relationship to the mosquito repellent qualities of the compounds released from the participants' skin. There were no articles on the transdermal (patch) use of thiamine.

A July, 2002 article in the New England Journal of Medicine has a very pertinent study of the efficacy and duration of action of several different repellents (thiamine not included), noting that 10% citronella oil can protect you for all of 19 minutes!

(5) Would I rely on this product to protect me in a country where malaria is endemic?
Absolutely NOT!

Note these sad facts: More than 40% of the world's population is at risk of malaria, and more than a million people die of it each year. Malaria kills a child every 30 seconds: 90% of people who die from malaria are children not yet 5 years of age, and most (90%) of these deaths take place in sub-Saharan Africa. (Greenwood BM, Bojang K, Whitty C, et al. Malaria. Lancet 2005;365:1487-8.)

One website promotes this product by asking: "Are you planning to travel abroad to areas possibly infested by various insect populations?" and "Are you in an area where you know that mosquito-borne diseases are present?" Unless they mean northern Canada or parts of the USA, where the mosquitoes don't carry malaria, this is a reckless product recommendation. If I had to decide what product to use to prevent my own DEATH, I'd probably go with the one that has substantial evidence to prove that it works (DEET + prophylactic antimalarial oral medication + permethrin-treated bednets).

Aside from malaria, I know for sure that there are no published studies showing that this patch has any efficacy for prevention of yellow fever, dengue fever, Japanese encephalitis, or any of ther other mosquito-borne diseases.

(6) Should pregnant women use products like this because they are safer than the alternatives?
It should be pointed out that pregnant women need particularly good protection from malaria (DEET and certain antimalarials are okay), since malaria will kill a fetus and occasionally the mother too, since immunity is lower in pregnancy. Several deaths have occured in Canada due to misinformation on the prevention or treatment of malaria in travelers. If we are just talking about nuisance mosquitoes, then you may as well use any product that isn't known to be unsafe.

The Canadian Medical Association Journal publishe
d a critical review (DEET-based insect repellents: safety implications for children and pregnant and lactating women. August 5, 2003; 169 (3)) which concludes that "There is no evidence that the use of DEET by pregnant or lactating women poses a health hazard to unborn babies or children who are breast-feeding."
Another quote from the promotional website:
"Just one small OMEZONE TM Defend Patch, applied discreetly on any hairless area of the body creates an invisible virtually impenetrable shield against the ill effects of mosquitoes and the diseases they may carry."

Yeah, well I'll bet that the mosquitoes probably find it hard to bite you THROUGH the patch. I propose that the application of several hundred patches, so as to cover every bit of exposed skin, would be effective as a mosquito repellent.

23 comments:

James Krane said...

Hello,
My name is James Krane and I am the Canadian importer of the Insect Defend Patch. After reading your post I felt compelled to write a comment to answer some of your questions and offer some additional information.

I would like to begin by thanking you for writing about the patch. Your reaction to this breakthrough product is common. It almost sounds too good to be true. I felt the same way when I was first introduced to the patch over 4 years ago.

Before Health Canada would accept our Natural Health Product application (and allow us to seel it in Canada)we were required to conduct efficacy testing which proved our claim that the patch is an effective Mosquito bite deterrent. We conducted the testing in two consecutive years with a company named Arcturus Testing in Guelph. The facilitator is a professor at the University of Guelph who has tested virtualy every mosquito protection product on the Canadian market. The results indicate that there has never been anything that works in this manner for such a long time. They have yet to be publised. I will gladly provide you with them upon request.

You are correct in your research that Vitamin B1 taken orally has never been proven to be effective. The difference is that when applied through a trans dermal patch, it is absorbed directly into the bloodstream and does not need to go through a person's digestive system.

The patch also releases the B1 gradually into the body over a 24 hour period and there is usually a 12 hour residual effect depending on a person's metabolism or whether they drink or smoke (which both use up thiamine in the body).

We have found that the patch is most effective when a person is perspiring, as this is how any excess B1 exits the body. This is when deet products become less useful as they dilute or wash off entirely. Again, this is why the patch has proven to be so successful in malaria ridden countries where the climate is hotter. It is currently sold in 14 countries and is in development in another 20 or so at the time of writing.

We have provided patches to the Global Foundation for use by their malaria innoculation teams working in Africa and Central America. Retailers in Nigeria, Kenya, Nairobi, South Africa, Botswana, and Tanzania have them available for tourists. Our goal is to eventually be able to get them for free to the people who really need them and can't afford them. It would be incredible to help save lives.

Many, many people are justifiably concerned about using deet products. Health Canada says to avoid using it everyday and when you go inside to wash it off. People who live or work in areas where biting insects are a problem have had no options until now.

A good example are the forest fire fighters working with the Ministry of Natural Resources based in Sudbury, Ontario. These guys really sweat and the deet would just run off into their eyes and mouths. They began using the patch this spring to rave reviews.

In Canada, when temperatures are cooler and a person is not perspiring, our testing has proven that mosquitoes may land but do not immediately bite. We were able to consistently measure a 640% increase in "time to bite". This effectively gives the wearer, at the very least, a chance to Defend themselves...hence the name.

The product works very well for people who are active. This is one of the reasons they are so effective for children. Our recommendation is to use the patch as your first line of defense because it can be used everyday. Use deet products sparingly, and according to Health Canada guidelines, to supplement the patch when you will be exposed to high biting pressure environments.

The Insect Defend Patch can be purchased at your local Home Hardware store as well as many independent retailers. You will be able to see us on the 2009-2010 season of CBC's Dragon's Den.

For any other questions or comments we can be reached through our website at www.safetyinmotion.net

Gardenista said...

Thanks for the info. I hope that the research eventually makes it into a peer-reviewed journal, as that would disseminate the information to those searching medical databases. I would certainly try this patch for gardening in Canada. However, I would still use a combination of things, including permethrin-impregnated bednets, DEET, anti-malarial prophylactic drugs and adequate clothing in malarious countries. The risk of death from fatal mosquito-borne disease is much too high to rely exclusively on products without extensive published research.

Az said...

I live in the Ottawa valley where we have a lot of black flies in the spring and then mosquitos for the summer. I first tried the Insect Defend Patch in early May (black fly season) and wore it at a park (where there were a lot of people around playing soccer and on the playground). I noticed that my friends were getting bitten, but I wasn't (the black flies would land on my skin and just wander around for a bit before flying away). So, I went back to the store and purchased 6 packages. However, over the course of several weeks, I became less impressed and am now convinced that they are useless. Last week, my family went on a hike in the woods. We applied the patch about 2 hours prior to the start. We then paddled a canoe across the river to the Quebec side for our hike. Once we entered the bush, we were attacked by mosquitoes. Within 15 minutes, we pulled out the Muskol (Deet) and lathered ourselves - no more mosquito problems for the rest of the hike.

So, I think that it may be of some minor benefit if there are other blood supplies nearby for the mosquitoes, but if you are the only meal, then they don't care about the B1 on your skin and they will bite.

Gardenista said...

Az- that's an interesting observation! I guess a generous blood buffet would create less bites than some lonely souls out in the forest.

Marlene said...

Hi. My husband I decided to try the patch after seeing the pitch on Dragon's Den last year. The first time we used it golfing it worked fine - no bites. However my husband commented that his arm was 'bruised', i.e., blue, where the patch was. I thought he was a little crazy. We used the patch again yesterday for golf. Again, no bites in very hot and humid conditions so that was very effective. HOWEVER, I started noticing an acrid smell coming from my body. It was not pleasant. Turns out it is the Thiamine coming out of my pores and now I smell disgusting still on the following day. I just keep apologizing to people in the office with an explanation.
On an even more serious note, last evening my husband again commented that his arm was 'bruised' and he was feeling hot, sweaty and generally not very great. I checked out B1 Thiamine today and found that in heavy doses such as the patch contains, it can cause serious reactions in some people. I am only glad he did not go into anaphylactic shock, which is the most serious side effect of Thiamine overdose. I am discarding the remaining patch and will go back to using spray.

Corey j said...

Thimine does give these affects. And Marlene , take a shower before you go to work. The product works great and it does not smell guys .

Anonymous said...

The product is great and people need to try this for themselves .
My family and i love it ,never had a problem . And no Thimicine does not give alergic reactions and yes that lady did not take a shower this is why she smelled the next day at work. The product is great .

Anonymous said...

I have now tried the patch on 3 different occasions. Putting it on at least 2hrs prior to "needing" it. I've never made it past the 1.5hr stage due to the smell! I've tried different parts of my body as far away from my nose as possible and no matter what....still want to gag at the smell!

Anonymous said...

yup - definitely a smell, at least for us. It would seem to make some sense if that is how it is designed to work and maybe it is just various bodies handle it differently?!

From recent readings it sounds like "strong smells" reduce the tracking ability of mosquitoes (from reading up on Garlic Spray) so I could see that they may wander off if there are easier targets.

For us we are still testing. Seems like it "might" work under light conditions of mosquitoes but not under heavy attacks...our acreage is under siege and just mowing the lawn is a battle.

Anonymous said...

My youngest son is always tormented by mosquitos. Bugs from miles away seem to flock to him.

Tried the patches last weekend at the cottage. Only put it on my son, and he was the only one without a bite. Didn't emit an odor and stayed on through hours of swimming. I will continue to use them rather than a spray.

Shannon said...

I tried the patch and I smelled a odd odor but my friends didn't have the same problem as me. I also had a problem with removing the patch it seemed as though it was glued to my skin. I defiantly had an uncomfortable time removing it, and I also had a lot of residue after finally taking the patch off.

Anonymous said...

Our family has been using these patches for about 4 years. They work great! My daughter and I produce the odor caused by the Vitamin B. My husband does not. I might note, if you are over 150lbs you need two patches. We will continue to use this product.

Anonymous said...

We love them! I keep mine on until I feel it has lost it's potency, maybe 3 days. Yes, there is an odor on the skin in the morning, but a shower (with soap) takes care of that... and perhaps some scented lotions.
Note: I cut mine in half and save the other half, it seems to work just fine. Put it on your torse area, where it's hidden, that way nobody can see it. When it's time to take it off and you're left with adhesive markings, use rubbing alcohol and a washcloth to dissolve it.
I'd rather use these than chemical sprays.

Anonymous said...

oops... I meant to say "put it on your TORSO area."

Maurise Gelman said...

Research has proven that mosquitoes are attracted to or repelled by odors. I haven’t found a patch like that, but I guess product is a very nice innovation. What’s good about this is the fact that there is an alternative product for those people who don’t like mosquito repellant lotions or oils. I know it’s been almost three years after this post, and I hope the efficacy of the patch has been already tried and tested.

[ Maurise Gelman ]

Anonymous said...

Just wondering if these are safe to wear for breastfeeding moms?

Minna said...

It is interesting reading the comments from Marlene. I used the Insect Defend Patches and they don't work. Not to mention that I also got bruising from the patch as well as tightness in my throat when I used it. I put it on 2 hrs prior to exposure to the bugs.

Not to mention the package says good for children over 1 yrs old and the instructions inside says don't use on children under 12 yrs. I am glad I didn't use these on my kids. There should be a large warning about the side effects that can happen when you get a high dosage of thiamine in your system.

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