EWG’s 2018 Guide to Bug Repellents : Protecting from Ticks and Lyme Disease
Do Repellents Stop Ticks?
No single chemical completely repels American ticks. Do not rely on any product to keep ticks away. Check for ticks at the end of the day or when returning indoors.
The Environmental Protection Agency has approved products using picaridin, IR3535, DEET and Oil of Lemon Eucalyptus/PMD for use as tick repellents with a protection time greater than two hours. In lab studies DEET only stops three of every four ticks, and products with lower concentrations were less effective. Researchers test tick repellents by timing how long it takes for a tick to walk over a volunteer’s repellent-coated skin. The effectiveness of tick repellents can vary according to species and lifecycle stage of the tick.
There are few peer-reviewed scientific studies of the efficacy of these chemicals against deer ticks. Two studies indicate that IR3535 repels deer ticks as well as or better than DEET.1,2 A 2013 science review of efficacy against deer ticks lists a mean protection time of 7.2 hours for IR3535, 3.5 hours for DEET, 2.7 hours for Oil of Lemon Eucalyptus/PMD and 2.5 hours for picaridin.3
In one study, three repellents – 33 percent DEET, 20 percent picaridin and 20 percent IR3535 – repelled lone star ticks for some hours, but 10 percent IR3535 did not.4
Does treated clothing keep ticks away?
According to the Centers of Disease Control and Prevention, clothing and gear treated with 0.5 percent permethrin, a registered pesticide, may be a good way to prevent tick bites.5
Available efficacy testing indicates that permethrin-treated clothing provides a higher level of protection from ticks than repellents applied to the skin. However, permethrin is not without some concern. It is neurotoxic and the EPA has been classified it as a likely human carcinogen. It is highly toxic to the environment, especially to fish and other aquatic life. But a 2009 EPA review said that “permethrin factory-treated clothing is unlikely to pose any significant acute or chronic hazard to people,”6 including toddlers, pregnant women and nursing mothers.
Use permethrin products with caution, read labels, and wash all treated clothing separately from other clothing.
1 Brooke W. Bissinger and R. Michael Roe, Tick Repellents: Past, Present, and Future. Pesticide Biochemistry and Physiology, 2010, 96(2):63-79. Available at doi.org/10.1016/j.pestbp.2009.09.010
2 J.F. Carroll et al., Repellency of DEET and SS220 Applied to Skin Involves Olfactory Sensing by Two Species of Ticks. Medical and Veterinary Entomology, 2005, 19(1):101-106. Available at doi.org/10.1111/j.0269-283X.2005.00559.x
3 Eleonora Lupi et al., The Efficacy of Repellents Against Aedes Anopheles, Culex and Ixodes spp. – A Literature Review. Travel Medicine and Infectious Disease, 2013, 11, 374-411. Available at www.travelmedicinejournal.com/article/S1477-8939(13)00173-7/pdf
4 J.F. Carroll et al., Repellency of DEET and SS220 Applied to Skin Involves Olfactory Sensing by Two Species of Ticks. Medical and Veterinary Entomology, 2005, 19(1):101-106. Available at doi.org/10.1111/j.0269-283X.2005.00559.x
5 Preventing Tick Bites. Centers for Disease Control and Prevention, 2018. Available at www.cdc.gov/ticks/avoid/on_people.html
6 Repellent-Treated Clothing: Safety of Permethrin in Factory-Treated Clothing. Environmental Protection Agency, 2017. Available at www.epa.gov/insect-repellents/repellent-treated-clothing