Tick Repellents Compared: DEET, Picaridin, and Permethrin

The numbers out of Augusta keep moving in the wrong direction. Maine logged about 3,218 reported Lyme cases in 2024, up from 2,943 the year before, along with 1,284 anaplasmosis cases and 309 babesiosis cases (Maine CDC). By mid-October 2025 the state had already passed those totals, with 3,569 Lyme cases on the books. Picking a repellent stopped being a summer-only chore years ago. Maine CDC notes that deer ticks can crawl out any time winter temperatures climb above freezing, which in a mild January is more often than most of us would like.

Two jobs, not one

People talk about tick repellent as if it were a single product. It really splits into two categories that do different work.

One goes on your skin and tells ticks to keep moving. The other goes on your clothes and gear, where it doesn’t just repel but can actually kill ticks that crawl across the fabric. Confusing the two is how people end up spraying the wrong thing on the wrong surface. The skin products are DEET and picaridin (plus a few others). The clothing treatment is permethrin, and it belongs on cloth only, never on skin.

For a wider look at the disease side of all this, our complete Maine and New Hampshire tick and Lyme guide covers the species, the seasons, and what to watch for after a bite.

DEET: the long-tested benchmark

DEET has been the reference point for decades, and most repellent research still measures everything else against it. The University of Maine Cooperative Extension Tick Lab, based in Orono, advises that repellents with 20 to 30 percent DEET on exposed skin and clothing can repel ticks for several hours. Follow the label, every time.

How long is “several hours,” exactly? One human-subject study run under the U.S. EPA standard protocol found that 20 percent DEET gave median complete protection times of roughly 4 to 4.5 hours against blacklegged tick nymphs, the tiny poppy-seed-sized stage that does most of the disease transmitting in our region (Experimental and Applied Acarology, 2015). That is a useful window for a morning hike, less so for a full day in the field without reapplying.

DEET’s main drawback is cosmetic and practical. It can feel greasy, it has a smell some people dislike, and it dissolves certain plastics and synthetic fabrics. Anyone who has watched it haze a pair of sunglasses or eat into a watch strap knows the feeling. None of that changes the basic fact that it works. For a quick walk around a wooded property line in Bethel or Berlin, a lower-percentage DEET product covers you fine. For a long day bushwhacking, plan on reapplying, because that 4-hour window is real and the afternoon ticks don’t take a break.

Picaridin: the quiet alternative

Picaridin has been gaining ground on DEET, and for good reason. The National Pesticide Information Center notes it is taking market share because of its low irritation, and unlike DEET it doesn’t dissolve plastics or synthetic materials. No melted sunglasses.

Does it work as well? Harvard Medical School’s Lyme resource reports that repellents with 20 percent picaridin can protect against tick bites for eight to 14 hours, depending on the product. A 2018 review in the Journal of Travel Medicine compared the two head to head and found little difference between DEET and picaridin at the same dose, with some evidence that picaridin lasts a bit longer.

So the honest summary: at comparable concentrations, picaridin holds its own. It is odorless, less greasy, and gentler on your gear. If DEET has always bugged you, this is the swap worth trying. The longer protection window is the practical edge here. A 20 percent picaridin product stretching toward the back half of a workday means one application instead of two, which matters more than it sounds when you are halfway up a trail with your hands full.

Permethrin: the layer that does the most

Permethrin is the one that surprises people. It isn’t a skin repellent at all. You treat clothing, boots, and gear with it, then let it dry before wearing. The CDC says permethrin-treated boots, clothing, and camping gear stay protective through several washings, so one application carries you through a stretch of the season rather than a single outing.

The evidence here is strong. A randomized, double-blind controlled trial of outdoor workers in North Carolina, the kind of people who spend whole days in tick habitat, found that permethrin-impregnated uniforms cut tick bites by about 82 percent in the first year (American Journal of Preventive Medicine, 2014). That is a meaningful reduction for forestry crews, trail volunteers, and anyone whose job or hobby keeps them in the brush.

The rule that matters most: permethrin goes on fabric, period. UMaine Extension is blunt about not applying it directly to skin. If you want the full breakdown of factory-treated versus spray-on options and the safety questions, see our permethrin-treated clothing guide.

What “EPA-registered” actually means

You will see “EPA-registered” on the better products, and it is worth understanding. The CDC recommends EPA-registered repellents containing DEET, picaridin, IR3535, oil of lemon eucalyptus, para-menthane-diol, or 2-undecanone. Registration means the manufacturer handed the EPA technical data on the product’s safety. The agency even runs a free search tool that lists only registered skin-applied repellents, and it lets you filter by target pest, protection time, and active ingredient.

The CDC adds that when used as directed, these repellents are proven safe and effective, even for pregnant and breastfeeding women, though it advises against oil of lemon eucalyptus or PMD on children under three. As always, the label is the instruction manual.

Putting it together for the trail and the yard

The two methods are not rivals. Federal guidance recommends using them together: permethrin on clothing and gear, plus an EPA-registered skin repellent like DEET or picaridin on the skin you leave exposed. Treat the boots and pants, cover the ankles and wrists with whichever skin product you tolerate, and you have closed most of the gaps a deer tick looks for.

Repellent is one layer of defense, not the whole wall. Keeping ticks out of the spaces where you actually live matters too, which is the focus of our guide to tick control in the yard. And if you do find one attached, the Orono lab will identify it and test it for pathogens Monday through Friday, then fold the data into its annual report on Maine tick submissions. That free service is one of the better tools we have in this corner of the country.

Sources

• Centers for Disease Control and Prevention. Preventing Tick Bites. 2024. https://www.cdc.gov/ticks/prevention/index.html
• U.S. Environmental Protection Agency. Find the Repellent that is Right for You. 2024. https://www.epa.gov/insect-repellents/find-repellent-right-you
• Centers for Disease Control and Prevention. Mosquitoes, Ticks, and Other Arthropods (CDC Yellow Book). 2024. https://www.cdc.gov/yellow-book/hcp/environmental-hazards-risks/mosquitoes-ticks-and-other-arthropods.html
• University of Maine Cooperative Extension. Personal Protection – Cooperative Extension: Tick Lab. 2024. https://extension.umaine.edu/ticks/management/personal-protection/
• University of Maine Cooperative Extension. Cooperative Extension: Tick Lab. 2025. https://extension.umaine.edu/ticks/
• Harvard Medical School. Preventing Tick Bites (picaridin/DEET protection times). 2024. https://www.lyme.health.harvard.edu/preventing-tick-bites/
• Journal of Travel Medicine. Mosquito repellents for the traveller: does picaridin provide longer protection than DEET? 2018. https://pubmed.ncbi.nlm.nih.gov/29718433/
• National Pesticide Information Center (Oregon State University / EPA). Picaridin General Fact Sheet. 2024. http://npic.orst.edu/factsheets/PicaridinGen.html
• American Journal of Preventive Medicine (PubMed). Long-lasting Permethrin Impregnated Uniforms: A Randomized-Controlled Trial for Tick Bite Prevention. 2014. https://pubmed.ncbi.nlm.nih.gov/24745637/
• Experimental and Applied Acarology (PubMed). Repellent efficacy of DEET, Icaridin, and EBAAP against Ixodes ricinus and Ixodes scapularis nymphs (Acari, Ixodidae). 2015. https://pubmed.ncbi.nlm.nih.gov/25936273/
• Maine Department of Health and Human Services / Maine CDC. Maine CDC Encourages Tick Bite Prevention This Fall. 2025. https://www.maine.gov/dhhs/news/maine-cdc-encourages-tick-bite-prevention-fall-fri-10172025-1200
• Maine CDC / Maine Tracking Network. Tickborne Diseases (annual Lyme, anaplasmosis, and babesiosis case counts). 2025. https://data.mainepublichealth.gov/tracking/tickborne

This article is for informational purposes only and does not constitute medical advice. Consult a qualified healthcare provider before making any health decisions.