mosquito biting a person's arm

Mosquitoes can put a real damper on enjoying the outdoors. When we were on our honeymoon, many years ago, we were camping in Grand Teton National Park. Even before we opened the car doors to set up our tent and camp stove, there were enormous mosquitoes hovering in large numbers to get a bite of our blood. Quite intimidating!

Why Are Some People Especially Enticing to Mosquitoes?

There seem to be significant differences among individuals with respect to how attractive mosquitoes find them. Some people start slapping biting mosquitoes the second they step outside, while others are rarely troubled at all.

A recent article at suggests several factors that may help explain this curious phenomenon. It turns out that blood type matters, and so does body temperature and the amount of carbon dioxide a person exhales. The microbial ecology of the skin may also have an effect on mosquitoes and their likelihood of taking a taste. Be wary at the backyard cookout: people drinking beer appear to be especially appealing to mosquitoes.

Does Vitamin B1 Scare Mosquitoes Away?

Q. I am a gardener and have always been a mosquito magnet. I read about vitamin B1 and have been taking it for several days. I just went outside this evening and didn’t get one bite! Usually they are all over me. I will continue to take B1 until cold weather.

A. There is almost no scientific research to support vitamin B1 (thiamine) against mosquitoes. That said, some readers report similar success. It may well be that thiamine works in conjunction with some of the other individual factors to make certain individuals less appealing.

We heard before from an individual who had good luck like you do:

Q. I have found vitamin B1 to be an effective deterrent for mosquito bites. I was recently in an area where I got multiple mosquito bites daily that itched unbearably. I developed open sores from scratching in my sleep, even when I used Benadryl or hydrocortisone cream.

In less than a week of taking vitamin B1 (500 mg per day), I have not had any more bites. I know there are studies that say vitamin B1 has no value for deterring insect bites, but my experience convinces me otherwise.

A. Thank you for sharing your testimonial. Some other readers have also found taking vitamin B1 (thiamine) helpful against mosquitoes. The research we have found, however, indicates that this vitamin is not effective as a systemic mosquito repellent (Journal of the American Mosquito Control Association, June, 2005). We could find no more recent research on the effects of thiamine against mosquito bites.

Another reader used B vitamins as a repellent in quite a different way:

Q. I was hiking high in the Canadian Rockies and the black flies were voracious. I didn’t have insect repellent with me because mosquitoes, fleas and other critters never bite me. I think that’s because I take B-complex and garlic, among other supplements, and they don’t like that.

Increasingly vexed by the black flies, I finally appropriated a B-complex 100 mg tablet I had with me. I smushed it up with some creek water, and then rubbed the bright yellow liquid all over myself. END OF PROBLEM! I admit, though, that I did look a bit jaundiced. What do you think about the efficacy of B-complex or other supplements in repelling bugs?

A. We love your story, but we’ve never heard of anyone else using vitamin B pills topically. With no studies, we wouldn’t dare venture a guess about effectiveness.

There was some preliminary research on thiamine, a B vitamin, taken orally to repel mosquitoes. Since it was conducted many decades ago, however, it would not meet today’s scientific standards and newer research has not confirmed the benefit. Nevertheless, some readers swear that this nutrient keeps mosquitoes from biting them.

Repelling Mosquitoes:

Individual body chemistry seems to have an important effect on whether and how well this remedy works. Most people need to apply a proven mosquito repellent such as DEET, picaridin or lemon eucalyptus oil. That is particularly true in places where mosquitoes may be transmitting malaria, Zika virus or West Nile virus. Although DEET sets the standard for repellents and has for decades, there are concerns about toxicity, especially if it is being used for extended periods or at high concentrations.

We have written here about mosquito repellents. It turns out that different species are more sensitive to one repellent than another (Travel Medicine and Infectious Diseases, Nov-Dec., 2013). That might explain why some people find taking thiamine helps, at least under certain conditions. Adding vanillin to mosquito repellents can extend the amount of time they are effective by about two hours.

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  1. Wanda

    I use thiamine when I hike. Normally, the skeeter bite immediate upon landing. When I take thiamine 300 mg I can smell the vitamin on my skin. It smells like a vitamin bottle and is strong. When a skeeter landed on my hand, I watched it. It walked around on my hand for a few seconds, then flew off without biting.

  2. Peggy

    I used a Bounce Fabric Softener strip pinned to my collar and the mosquitoes left us alone all summer. Has to be the original formula.

  3. Elizabeth

    My son was a flea magnet and further more, one bite lead to hives. Vitamin B1 tabs seemed to solve that problem. By the way, back then, we had large dogs and flea collars were almost useless and none of today’s flea meds for dogs were yet discovered. I added B1 to my dogs diet and it helped.

  4. D'Lain
    Houston, Texas

    For years now mosquitos rarely bite me. Some do once in a while but I never get a bump that gets itchy. I did when I was a kid though.
    Could this be because I took allergy shots for 10 years a long time ago. There may have been something in that shot that has saved me from pesky mosquitos.

  5. Daniel E Marsalek
    Rocky River, OH

    I haven’t been bitten in years, even before addding B12. I suspect that my other meds have made me “distasteful”.

  6. Geronimo


    YES, Mosquitoes really do not bite since they do not have teeth, but female Anopheles mosquitoes inject us with their saliva. This is alkaline and produces itching. It helps her withdraw some of our blood.

    Anyway, after we have been injected with this itchy saliva there is a simple remedy for this problem. Since the saliva is alkaline, we can neutralize it with an acid solution. That solution is vinegar.

    Take a tissue or cotton swab, wet it with vinegar and apply it to the injected area. Hold it on for about twenty minutes so the vinegar can penetrate. This will solve the itch.

    Vinegar is 5% acetic acid and non-toxic.

  7. Carey

    I have contact dermatitis, so I avoid scented products. Mosquitoes never bite me. But I noticed that if I wash my hands with scented soap in a public restroom, they will bite my hands.

    This may not help everyone, but may be helpful to some.

  8. Larry M

    I have some concerns about DEET. When camping, one of my companions slathered on the DEET, then poured a wine into a plastic wine cup (acrylic or polycarbonate, I’m not sure which). Her finger prints are permanently etched into the wine glass.

    We’re not talking about disposables here. These cups are thick, dishwasher-top-tray-safe, clear, reusable cups. I’m hesitant to consume a product that etches plastic.

  9. shirley

    I just read that krill oil is better that fish oil. I don’t take either one. Should I? I was once told by a doctor that people don’t need to take supplements it’s the companies that sell them that say you need them. What do you say?

  10. Sadie

    Hi! I am afraid of applying potentially toxic chemicals to my body, so I researched other means of repelling mosquitoes. I first tried a combination of lavender, eucalyptus, and peppermint oils. They were somewhat effective and repelled the bugs for about a half an hour. Then I came across an article that mentioned that Northeast Native Americans have used sage oil for centuries. So I bought a bottle of pure sage oil in a health food store and BINGO! It worked like a charm. It repels the bugs for about an hour and a half. You can apply it to your skin it as much as you want and it stays effective. I grow sage in my garden, so I picked a bundle of it and put it in the campfire, and it is wonderful at keeping the bugs away altogether. It even works with bees! The fragrance is pleasant and I will never need to buy a chemical again.

  11. Rosemary
    Jupiter, RL

    You mention that vanillin added to insect repelent will extend its coverage. What is vanillin?

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