Picaridin, citronella, and lemon eucalyptus are put to the test.
Natural Alternatives to DEET Mosquito Repellent
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Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.
DEET has been considered the most effective mosquito repellent. Unquestionably, read this editorial in The Journal of Family Practice; it should be the only mosquito repellent recommended by physicians, with no other repellent coming close. Given the dramatic efficacy, it’s hard to conceive that any other repellent would ever beat it. However, there are some rare reports of severe reactions to DEET, not to mention the fact that it can melt plastics, like eyeglass frames, and cellphone components, and many consumers find the odor and sensation on the skin unpleasant. Enter picaridin. Overall, studies have shown little difference between DEET and picaridin applied at the same dosage, with some evidence pointing to a superior persistence for picaridin––all without the irritancy, odor, and melted glasses.
No wonder it got Consumer Reports’ pick for the best overall insect repellent. Note that concentration matters. Their 20 percent picaridin product topped the list, but at 5 percent it was one of their worst-performing products. Any toxicity? Adverse effects, when occurring, primarily manifested as eye irritation/redness, vomiting, and oral irritation. But of course you’re not supposed to eat it, or spray it in your eyes. But even unintentional ingestion was associated only with relatively minor toxicity.
What about the electronic mosquito-repellent gizmos? There were 10 studies done, and all 10 found that there was no difference in the number of mosquitoes landing on people with or without the gizmos, and experiments out in the field confirm: no effect on preventing mosquito bites.
Picaridin was roughly based on a black pepper compound, but, like DEET, is a synthetic chemical. Are there any natural repellents? Of course, just because something is natural doesn’t mean it’s necessarily safe. Strychnine is a natural product of the strychnine tree, and ricin from castor beans is 100,000 times deadlier still. In fact, the top 10 most toxic poisons are all natural.
But let’s look at the mosquito-repellent effects of about 20 essential oils, compared to a placebo control group, and to DEET. The asterisks point to the significant results, so here’s a cleaner peek. As you can see, only five had any lasting effect at all. Peppermint and lemongrass oil were effective for 30 minutes. Spearmint and garlic oil started working, but didn’t even last that long. Cinnamon oil, though, reduced mosquito attraction for one and a half hours. The remaining essential oils had no significant effect on mosquito attraction at any time point, and this includes citronella.
Citronella was the most widely-used repellent before DEET was invented, and it is still used today in many formulations, despite inferior efficacy. At lower concentrations, it may only last a few minutes, and at higher concentrations, citronella can cause skin irritation. Compared to a complete protection time of six hours for DEET, citronella may only last 10 1/2 minutes. Therefore, citronella may be acceptable for brief exposure to nuisance mosquitoes, but it is not advised for protection if you really can’t afford to get bit. Essential oils, read this Family Medicine Journal editorial, have no effectiveness, and are not recommended. But that was before we learned about lemon eucalyptus, the only plant-based repellent recommended by the CDC––though it should not be used by pregnant women or children younger than three years of age.
Consumer Reports listed it as one of their top three picks, warding off mosquitoes and ticks for at least seven hours. All the other botanical products they tested failed. But 40 percent lemon eucalyptus was shown to prevent bites for 4 to 7 hours after application for aggressive species of mosquitoes, and for greater than 12 hours for less aggressive mosquitoes––a period of prevention greater than at least a 10 percent DEET repellent.
Please consider volunteering to help out on the site.
- Margo KL. DEET is the most effective mosquito repellent. J Fam Pract. 2002;51(10):822.
- Logan JG, Stanczyk NM, Hassanali A, et al. Arm-in-cage testing of natural human-derived mosquito repellents. Malar J. 2010;9:239.
- Goodyer L, Schofield S. Mosquito repellents for the traveller: does picaridin provide longer protection than DEET?. J Travel Med. 2018;25(suppl_1):S10-S15.
- Insect Repellent Buying Guide. Consumer Reports. May 2016.
- Charlton NP, Murphy LT, Parker Cote JL, Vakkalanka JP. The toxicity of picaridin containing insect repellent reported to the National Poison Data System. Clin Toxicol (Phila). 2016;54(8):655-658.
- Enayati A, Hemingway J, Garner P. Electronic mosquito repellents for preventing mosquito bites and malaria infection. Cochrane Infectious Diseases Group, ed. Cochrane Database Syst Rev. 2007;2:CD005434.
- Maia MF, Moore SJ. Plant-based insect repellents: a review of their efficacy, development and testing. Malar J. 2011;10 Suppl 1(Suppl 1):S11.
- Islam J, Zaman K, Duarah S, Raju PS, Chattopadhyay P. Mosquito repellents: An insight into the chronological perspectives and novel discoveries. Acta Trop. 2017;167:216-230.
- Leal WS. The enigmatic reception of DEET - the gold standard of insect repellents. Curr Opin Insect Sci. 2014;6:93-98.
- Mitra S, Rodriguez SD, Vulcan J, et al. Efficacy of Active Ingredients From the EPA 25(B) List in Reducing Attraction of Aedes aegypti (Diptera: Culicidae) to Humans. J Med Entomol. 2020;57(2):477-484.
- Katz TM, Miller JH, Hebert AA. Insect repellents: historical perspectives and new developments. J Am Acad Dermatol. 2008;58(5):865-871.
- Yates J. Advice for protection against mosquitoes and ticks. Am Fam Physician. 2015;91(11):754-755.
- Yoon JK, Kim KC, Cho Y, et al. Comparison of Repellency Effect of Mosquito Repellents for DEET, Citronella, and Fennel Oil. J Parasitol Res. 2015;2015:361021.
- Insect repellent Recommendations. Consumer Reports.
Motion graphics by Avo Media
Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.
DEET has been considered the most effective mosquito repellent. Unquestionably, read this editorial in The Journal of Family Practice; it should be the only mosquito repellent recommended by physicians, with no other repellent coming close. Given the dramatic efficacy, it’s hard to conceive that any other repellent would ever beat it. However, there are some rare reports of severe reactions to DEET, not to mention the fact that it can melt plastics, like eyeglass frames, and cellphone components, and many consumers find the odor and sensation on the skin unpleasant. Enter picaridin. Overall, studies have shown little difference between DEET and picaridin applied at the same dosage, with some evidence pointing to a superior persistence for picaridin––all without the irritancy, odor, and melted glasses.
No wonder it got Consumer Reports’ pick for the best overall insect repellent. Note that concentration matters. Their 20 percent picaridin product topped the list, but at 5 percent it was one of their worst-performing products. Any toxicity? Adverse effects, when occurring, primarily manifested as eye irritation/redness, vomiting, and oral irritation. But of course you’re not supposed to eat it, or spray it in your eyes. But even unintentional ingestion was associated only with relatively minor toxicity.
What about the electronic mosquito-repellent gizmos? There were 10 studies done, and all 10 found that there was no difference in the number of mosquitoes landing on people with or without the gizmos, and experiments out in the field confirm: no effect on preventing mosquito bites.
Picaridin was roughly based on a black pepper compound, but, like DEET, is a synthetic chemical. Are there any natural repellents? Of course, just because something is natural doesn’t mean it’s necessarily safe. Strychnine is a natural product of the strychnine tree, and ricin from castor beans is 100,000 times deadlier still. In fact, the top 10 most toxic poisons are all natural.
But let’s look at the mosquito-repellent effects of about 20 essential oils, compared to a placebo control group, and to DEET. The asterisks point to the significant results, so here’s a cleaner peek. As you can see, only five had any lasting effect at all. Peppermint and lemongrass oil were effective for 30 minutes. Spearmint and garlic oil started working, but didn’t even last that long. Cinnamon oil, though, reduced mosquito attraction for one and a half hours. The remaining essential oils had no significant effect on mosquito attraction at any time point, and this includes citronella.
Citronella was the most widely-used repellent before DEET was invented, and it is still used today in many formulations, despite inferior efficacy. At lower concentrations, it may only last a few minutes, and at higher concentrations, citronella can cause skin irritation. Compared to a complete protection time of six hours for DEET, citronella may only last 10 1/2 minutes. Therefore, citronella may be acceptable for brief exposure to nuisance mosquitoes, but it is not advised for protection if you really can’t afford to get bit. Essential oils, read this Family Medicine Journal editorial, have no effectiveness, and are not recommended. But that was before we learned about lemon eucalyptus, the only plant-based repellent recommended by the CDC––though it should not be used by pregnant women or children younger than three years of age.
Consumer Reports listed it as one of their top three picks, warding off mosquitoes and ticks for at least seven hours. All the other botanical products they tested failed. But 40 percent lemon eucalyptus was shown to prevent bites for 4 to 7 hours after application for aggressive species of mosquitoes, and for greater than 12 hours for less aggressive mosquitoes––a period of prevention greater than at least a 10 percent DEET repellent.
Please consider volunteering to help out on the site.
- Margo KL. DEET is the most effective mosquito repellent. J Fam Pract. 2002;51(10):822.
- Logan JG, Stanczyk NM, Hassanali A, et al. Arm-in-cage testing of natural human-derived mosquito repellents. Malar J. 2010;9:239.
- Goodyer L, Schofield S. Mosquito repellents for the traveller: does picaridin provide longer protection than DEET?. J Travel Med. 2018;25(suppl_1):S10-S15.
- Insect Repellent Buying Guide. Consumer Reports. May 2016.
- Charlton NP, Murphy LT, Parker Cote JL, Vakkalanka JP. The toxicity of picaridin containing insect repellent reported to the National Poison Data System. Clin Toxicol (Phila). 2016;54(8):655-658.
- Enayati A, Hemingway J, Garner P. Electronic mosquito repellents for preventing mosquito bites and malaria infection. Cochrane Infectious Diseases Group, ed. Cochrane Database Syst Rev. 2007;2:CD005434.
- Maia MF, Moore SJ. Plant-based insect repellents: a review of their efficacy, development and testing. Malar J. 2011;10 Suppl 1(Suppl 1):S11.
- Islam J, Zaman K, Duarah S, Raju PS, Chattopadhyay P. Mosquito repellents: An insight into the chronological perspectives and novel discoveries. Acta Trop. 2017;167:216-230.
- Leal WS. The enigmatic reception of DEET - the gold standard of insect repellents. Curr Opin Insect Sci. 2014;6:93-98.
- Mitra S, Rodriguez SD, Vulcan J, et al. Efficacy of Active Ingredients From the EPA 25(B) List in Reducing Attraction of Aedes aegypti (Diptera: Culicidae) to Humans. J Med Entomol. 2020;57(2):477-484.
- Katz TM, Miller JH, Hebert AA. Insect repellents: historical perspectives and new developments. J Am Acad Dermatol. 2008;58(5):865-871.
- Yates J. Advice for protection against mosquitoes and ticks. Am Fam Physician. 2015;91(11):754-755.
- Yoon JK, Kim KC, Cho Y, et al. Comparison of Repellency Effect of Mosquito Repellents for DEET, Citronella, and Fennel Oil. J Parasitol Res. 2015;2015:361021.
- Insect repellent Recommendations. Consumer Reports.
Motion graphics by Avo Media
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Title
Natural Alternatives to DEET Mosquito Repellent
LicenseCreative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)
Content URLDoctor's Note
If you missed the first video on this topic, see Is DEET the Best Mosquito Repellent?.
And check out Does Eating Garlic Reduce Mosquito Bites? and Are Beer, Bananas, and B Vitamins Mosquito Repellents?.
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