Insects are the most successful group of creatures on earth, greatly outdoing mammals in number of species and sheer mass of life. Furthermore, despite great effort, human attempts to eliminate certain insects, such as mosquitoes, have utterly failed. In insects, it appears, humans have met their match.
When it comes to the more mundane level of avoiding insect bites, however, our species is doing a bit better. The chemical DEET (N,N-diethyl-3-methylbenzamide), found in almost all insect repellants, is highly successful especially against mosquitoes, flies, fleas, and ticks.
Contrary to popular belief, DEET appears to be a very safe substance when used in a normal fashion. After many decades of use by millions of people, use of DEET has only been associated with a small number of adverse reactions, and those side effects that have been reported seem to represent unusual personal responses rather than toxicity in the ordinary sense.1
Medical treatment for bites that have already occurred consists primarily of soothing topical treatments.
Due to fears about the safety of DEET (probably unfounded), many natural products have been marketed as safer substitutes. However, while some of these may be effective to a certain extent, none matches the power of the chemical.
One of the best of these appears to be a proprietary product containing soybean oil and geranium oil. In a small but well-designed study, this product, when applied to the skin, prevented insects from biting for an average of about 90 minutes.2 This benefit was equivalent to that of a low-strength DEET repellant (4.75%). However, researchers found that high-strength DEET repellants (24%) provided about 300 minutes of protection.
Proprietary bath lotions marketed to repel insects do not appear to provide more than a slight level of bite protection (unless DEET is added to them).2–4
Various essential oils, applied topically, have also shown promise for preventing insect bites, but the supporting evidence remains preliminary. Some commonly used essential oils include the oil of eucalytpus, citronella grass (Cymbopogon winterianus), clove , hairy basil (Ocimum americanum), kaffir lime (Citrus hystrix), lemongrass, patchuli, pine, turmeric, and vanilla.5–7, 11-12 Citronella candles and incense appear to reduce the number of bites by less than 50%.8
The herb garlic, when taken by mouth, may act as a mild insect repellant. A 20-week double-blind, placebo-controlled trial followed 80 Swedish soldiers and measured the number of tick bites received during the garlic and the placebo treatments.9 The results showed a modest but statistically significant reduction in tick bites when soldiers consumed 1,200 mg of garlic daily. However, another study failed to find one-time use of garlic helpful for repelling mosquitoes.13
Wrist bands impregnated with mosquito repellants do not appear to offer more than marginal efficacy.2 Sonic mosquito repellers do not appear to work at all.10 Oral vitamin B1 also appears to be completely ineffective.2
For people who have already been bitten, topical creams containing such herbs as aloe, calendula, chamomile, goldenseal, licorice, and marshmallow are often recommended, but there is no evidence that they are effective.
For a discussion of homeopathic approaches to insect bites and stings, see the homeopathy database.
1. Qiu H, Jun HW, McCall JW. Pharmacokinetics, formulation, and safety of insect repellent N,N-diethyl-3-methylbenzamide (deet): a review. J Am Mosq Control Assoc. 1998;14:12–27.
2. Fradin MS, Day JF. Comparative efficacy of insect repellents against mosquito bites. N Engl J Med. 2002;347:13–18.
3. Magnon GJ, Robert LL, Kline DL, et al. Repellency of two deet formulations and Avon Skin-So-Soft against biting midges (Diptera: Ceratopogonidae) in Honduras. J Am Mosq Control Assoc. 1991;7:80–82.
4. Schreck CE, McGovern TP. Repellents and other personal protection strategies against Aedes albopictus. J Am Mosq Control Assoc. 1989;5:247–250.
5. Oyedele AO, Gbolade AA, Sosan MB, Adewoyin FB, et al. Formulation of an effective mosquito-repellent topical product from lemongrass oil. Phytomedicine. 2002;9:259–262.
6. Tawatsin A, Wratten SD, Scott RR, Repellency of volatile oils from plants against three mosquito vectors. J Vector Ecol. 2001;26:76–82.
7. Ansari MA, Razdan RK. Relative efficacy of various oils in repelling mosquitoes. Indian J Malariol. 1995;32:104–111.
8. Lindsay LR, Surgeoner GA, Heal JD, Evaluation of the efficacy of 3% citronella candles and 5% citronella incense for protection against field populations of Aedes mosquitoes. J Am Mosq Control Assoc. 1996;12:293–294.
9. Stjernberg L, Berglund J. Garlic as an insect repellent [letter]. JAMA. 2000;284:831.
10. Coro F, Suarez S. Review and history of electronic mosquito repellers. Wing Beats 2000;11:6–7, 30–32.
11. Traboulsi AF, El-Haj S, Tueni M et al. Repellency and toxicity of aromatic plant extracts against the mosquito Culex pipiens molestus (Diptera: Culicidae). Pest Manag Sci. 2005;61:597-604.]
12. Trongtokit Y, Rongsriyam Y, Komalamisra N, Apiwathnasorn C. Comparative repellency of 38 essential oils against mosquito bites. Phytother Res. 2005;19(4):303-9.
13. Rajan TV, Hein M, Porte P et al. A double-blinded, placebo-controlled trial of garlic as a mosquito repellant: a preliminary study. Med Vet Entomol. 2005;19:84-9.
Last reviewed September 2014 by EBSCO CAM Review Board
Last Updated: 9/18/2014