DEET-Free Insect Repellent: How IR3535 Works and When to Use It

Short answer: IR3535 is a DEET-free insect repellent active. It’s registered by the EPA and is one of the active ingredients the CDC lists for protection against mosquitoes and ticks. Crews choose it when they want protection without DEET.

How insect repellent works

Mosquitoes and ticks find you by carbon dioxide, body heat and skin odor. A repellent makes your skin harder to find or less attractive, so they don’t land and bite. Repellents don’t kill insects. They keep them off you for a set time, then you reapply.

The repellents the CDC points to

CDC guidance recommends EPA-registered repellents with one of these active ingredients: DEET, picaridin (icaridin), IR3535, oil of lemon eucalyptus (OLE) or para-menthane-diol (PMD), and 2-undecanone. The CDC says EPA-registered repellents are safe and effective when used as directed. It also says the effectiveness of non-registered “natural” repellents isn’t known, and that pure lemon eucalyptus essential oil is not the same as registered OLE.

• DEET: the best-known option. Some people dislike the smell and feel, and it can damage some plastics and synthetic fabrics.
• Picaridin: nearly odorless and doesn’t harm plastics.
• IR3535: DEET-free. The CDC groups it with repellents that are synthetic versions of natural materials. Used in lotions and sprays.
• OLE / PMD: plant-based. Not for children under 3.

Use the EPA’s Find the Repellent That Is Right for You tool to compare protection times for specific products.

Ticks and Lyme disease on the job

Ticks are most active in warmer months, roughly April through September, in brush, tall grass and wooded edges, exactly where tree crews, linemen, surveyors and landscapers work. Use an EPA-registered repellent on exposed skin, treat boots, pants and socks with permethrin (clothing only, never skin), and do a full tick check at the end of the shift. More on ticks and Lyme on the job.

Mosquitoes and West Nile

Mosquitoes bite most at dawn and dusk. Dump standing water around the yard, the shop and job trailers, and use repellent on exposed skin, reapplying as the label directs.

I.C. Insect Repellent

• Lotion: IR3535 10%, EPA Reg. No. 70759-2-91651. Spray: IR3535 20%, EPA Reg. No. 70759-3-91651.
• Repels mosquitoes and ticks for up to 8 hours. Don’t apply more than the label allows.
• DEET-free and odorless.
• Glove-tested: Class 2 rubber insulating gloves passed the ASTM D120 proof test after contact with the product.
• Lotion, FR clothing: FR-compatible. Arc tested on FR fabric (ASTM F2621), and the fabric stayed at Arc Category 2; flame tested (ASTM D6413) with no melting or dripping. These FR results are for the lotion.

Shop the lotion · Shop the spray

Quick answers

Is IR3535 safe? It’s EPA-registered for use on skin. Use it exactly as the label says.

Does it kill bugs? No. It repels them.

Does it smell? I.C. Insect Repellent is odorless.

Sources: CDC, Preventing Tick Bites; CDC/NIOSH, Mosquito-Borne Diseases in Workers: Repellents; EPA, Find the Repellent That Is Right for You.