What type of mosquito repellent is most effective?

Mosquitos find their quarry by detecting Carbon Dioxide that is emitted from the pores in the skin as well as breathing and sweating. The reason that Deet, Picardin, or any other repellant works is because it renders the targeted individual “invisible” to the mosquito. Citroenella candles, for example, mask and even combine with CO2, to render an individual or even a group “invisible”. Once you understand this simple truth, you will see that by not bathing and not changing clothes you leave the pores in the skin mostly clogged with dirt and oil. This effectively cuts down on the amount of CO2 that you emit and the mosquitos can’t find you.

I live in French Polynesia (tropical country) and I use monoi. I works very well against mosquitoes, you just have to put more every 3-4 hours. The mosquitoes here really like to bite the feet, especially when I’m working at my desk so I don’t bother covering my whole body with monoi, just my feet and ankles.

The US Center for Disease Control (CDC) recommends DEET, Picaridin, IR3535, and lemon eucalyptus oil (active ingredient being p-menthane 3,8-diol). There was also apparently a claim that catnip is 10x more effective than DEET at repelling mosquitoes, but I’ve never encountered any catnip-based repellents. Outdoor retailer REI has a pretty thorough comparison of the pros and cons of common insect repellents, but they don’t really cite research.

DEET seems to be agreed upon as the most effective insect repellent, but there are a lot of arguments about its safety.

The ATSDR (a sub-agency of the CDC) has a page on their site about the effect of DEET in humans. They cite several other studies and summarize reports of (many upsetting) side effects of DEET use, including this one:

A study was done involving 143 National Park Service employees at
Everglades National Park to determine the effects of DEET on varying
use groups. Exposure groups were classified as low (non-users), medium
(0.01-0.52 g/day) and high (0.71-69.38g/day) use of DEET. It was found
that 36 of the workers (25%) reported health effects that they
attributed to DEET. These effects included rashes, skin or mucous
membrane irritation, transient numb or burning lips, dizziness,
disorientation, and difficulty concentrating. Headache and nausea were
also reported. A statistically significant difference was not found
between reported effects from high-exposure and medium-exposure
workers, although the incidences were significantly higher than in the
non-users (McConnell et al. 1987).

This article from Field & Stream I think summarizes the matter best: there is no real consensus about the issue of DEET, and no singular authoritative voice on the subject. On a personal note, I avoid DEET almost entirely because I’d rather deal with insect bites (and take anti-malarials when traveling) than risk exposure to something potentially toxic to my central nervous system.

Finally, I’ve never come across any literature that says what medium of repellent is most effective (spray v. lotion). I think the concentration of the active ingredient is more likely to affect the product more than its viscosity.

P.S. My uncle has a hiking friend who swears that taking cayenne pepper capsules is the best insect repellent. I’m not really sure if there’s anything to back that up.

I live in a tropical country with a lot of mosquitoes in some beaches I regularly visit. The best mosquito repellent I know is all natural.

It’s vitamin B12. You start to ingest B12 capsules 2 weeks before travelling. Your skin will produce a natural protection with an odour mosquitoes really dislike. It’s better than any spray, chemical or citronella candles… cheap and clean!
Oh, sure, you can’t feel the smell, only the mosquitoes!

DEET is pretty much the mosquito repellant of choice. The more of it there is, concentration wise, the less pleasant, so scale your concentration based on the risk of mosquito-borne disease.

“Backyard party with friends” – probably a pretty low concentration. “Hell no, I will not be getting malaria while in Uganda” – I used 95% DEET. Stuff was vile, but it worked.

100% DEET is certainly very effective, but it’s hard on your skin. Try it but be prepared to back down to 25% or even 7%.

Some coworker went to a jungle tour in Thailand for 4 days or so. He said not washing and wearing the same clothes for the whole time he was on the tour worked much better for him than all the mosquito repellents the other tourists used 🙂

True story!