Do natural insect repellents work as well as DEET?

Protection time is what matters. Labs measure complete-protection time: how long a product stays completely bite-free.

DEET. A 23.8% DEET product gave a mean complete-protection time of 301.5 minutes, and higher concentrations lasted longer³. Across 102 publications, DEET at 20% or more gave the best protection against Aedes mosquitoes, up to 10 hours⁶. The American Academy of Pediatrics (AAP) notes that 10% DEET lasts about 2 hours and 30% about 5, with nothing gained above 50%⁸.

Picaridin. In a field test in northern Australia, 19.2% picaridin gave over 95% protection against Culex mosquitoes for 5 hours, against 7 hours for DEET, though every repellent protected poorly against Anopheles⁷.

Oil of lemon eucalyptus (PMD). In lab tests, PMD products were comparable to DEET but for shorter times⁴. The AAP lists 30% to 40% oil of lemon eucalyptus as lasting about 6 hours and 8% to 10% up to 2 hours, and notes that "pure" oil has not been tested for safety as a repellent or registered by the EPA⁸.

Essential oils and other "natural" products. A soybean-oil repellent protected for 94.6 minutes, and every other botanical tested for under 20 minutes. Repellent wristbands gave none³. In a 2020 lab study of 21 minimum-risk ingredients, some oils (cinnamon, peppermint, spearmint, lemongrass, garlic) cut mosquito attraction, yet only one of five commercial sprays worked even for 30 minutes⁵.

Ticks raise the stakes. Reported tickborne disease cases more than doubled from 2004 to 2016¹¹. Eleven unregulated botanical tick products repelled 63% of ticks on average in the first 1.5 hours and 3% between 2.5 and 6.5 hours, while DEET products repelled at least 97% throughout¹². In a Connecticut study, protective clothing was 40% effective against Lyme disease and tick repellents 20%¹.

For plant-oil safety, see Essential Oils: Safety and Usage; for tick-borne illness, see Lyme Disease: Natural Support.

Mosquito repellents head to head (Fradin and Day 2002). Fifteen volunteers tested seven botanical repellents, four DEET products, an IR3535 product, three wristbands, and a moisturizer in a controlled lab with fixed mosquito species, age, and hunger³. DEET-based products protected longest, and higher concentrations lasted longer: 23.8% DEET averaged 301.5 minutes. A soybean-oil product averaged 94.6 minutes, IR3535 22.9 minutes, and every other botanical under 20 minutes. Wristbands offered no protection³. The authors concluded that non-DEET repellents cannot be relied on for prolonged protection where disease risk is substantial³.

Review and olfactometer data. A literature review of 102 publications found DEET at 20% or more best against Aedes, citriodora (PMD) repellency lower, and many plant-based products short-lived; adding 5% vanillin extended protection by about 2 hours. Against Anopheles, DEET, icaridin (picaridin), IR3535, and PMD gave similar protection of 4 to 10 hours, and the review found no standardized study of tick-bite prevention⁶. A Y-tube olfactometer test of eight commercial products used a human hand as bait for Aedes aegypti and Aedes albopictus⁴. DEET worked over longer times on both species, PMD gave comparable results for shorter periods, citronella and geraniol products had no significant effect, and a vitamin B patch had none⁴.

Picaridin in the field. Frances and colleagues compared 19.2% picaridin, 20% DEET in ethanol, and 35% DEET gel against wild mosquitoes in northern Australia⁷. Against Culex annulirostris, picaridin gave over 95% protection for 5 hours and both DEET formulations for 7 hours, when collections ended⁷. Against Anopheles, picaridin and the 35% DEET gel held over 95% for only 1 hour and the 20% DEET solution fell below that, which the authors read as tolerance of Anopheles to repellents⁷.

Essential oils in the lab. In a Y-tube study of 21 ingredients from the EPA's minimum-risk 25(b) list and five commercial sprays made only from those ingredients, cinnamon, peppermint, spearmint, lemongrass, and garlic oils reduced attraction of Aedes aegypti to human odor⁵. Only one of the five commercial sprays did so, and only for up to 30 minutes⁵.

Natural tick repellents. Burtis and colleagues tested 11 "minimum risk" 25(b) exempt products and two DEET products on human fingers with Ixodes scapularis nymphs, hourly from 0.5 to 6.5 hours¹². DEET repelled at least 97% at every time. Ten of the 11 natural products matched DEET at 30 minutes (79% to 97%), only four did at 1.5 hours, and none worked from 2.5 to 6.5 hours¹². Neither label claims nor the listed oils predicted performance¹².

Tick-borne disease trend. From 2004 to 2016 the US recorded 642,602 vectorborne disease cases, and annual tickborne reports rose from over 22,000 to over 48,000, with Lyme disease making up 82% of tickborne reports¹¹.

Protective clothing and permethrin. In a Connecticut case-control study, protective clothing was 40% effective and routine repellent use 20% effective against Lyme disease, while tick checks and acaricide sprays on property were not¹. In a double-blind trial, 159 North Carolina outdoor workers received factory-permethrin or sham uniforms; over 1,045 reported tick bites, effectiveness was 0.82 (95% CI 0.66 to 0.91) in year one and 0.34 (-0.67 to 0.74) in year two².

Safety of DEET. In a randomized repellent trial in pregnancy (n = 897), women applied about 1.7 g of DEET daily in the second and third trimesters, a median total of 214.2 g. They had no neurologic, gastrointestinal, or skin effects, and there were no effects on survival, growth, or development at birth or at one year, though DEET reached 8% of the cord blood samples tested⁹. A review found the evidence does not support an increased risk in young children¹⁰.

Null and conflicting results. Some natural ingredients clearly work briefly: peppermint, cinnamon, and lemongrass oils reduced attraction in the lab⁵, and 10 of 11 botanical tick products matched DEET at 30 minutes¹². The problem is duration and consistency, not zero effect. Against Anopheles, the review reported 4 to 10 hours of average protection⁶, but the Australian field test saw over 95% protection for only about an hour⁷. The permethrin benefit was not significant in year two². No trial compared infection rates between DEET and botanical repellents.

Bottom line (confidence 4 of 5). DEET and picaridin outlast botanical products, and oil of lemon eucalyptus is the best natural alternative with shorter protection. In the tick studies, clothing did at least as well as sprays.