A research-backed comparison of the two most studied mosquito repellent active ingredients — their effectiveness, safety profiles, environmental impact, and what the science actually supports. Updated March 2026.
About this page: This resource compiles findings from peer-reviewed studies, CDC guidance, EPA registration data, and independent research on PMD and DEET. All claims are sourced. This page is maintained by The Superbloc and is intended as an educational resource — not medical advice. Always follow product label instructions and consult a healthcare professional for specific medical guidance.
What is PMD? · What is DEET? · Effectiveness Comparison · Key Clinical Studies · Safety & Toxicity · Use with Children · Environmental Impact · CDC & Regulatory Positions · Choosing the Right Repellent · References
What is PMD?
PMD (para-menthane-3,8-diol) is a naturally occurring compound found in the leaves of the lemon eucalyptus tree (Corymbia citriodora). When the leaves are distilled and the extract is refined to increase PMD concentration, the resulting product is known as Oil of Lemon Eucalyptus (OLE).
PMD can also be produced synthetically. Whether naturally derived or synthesized, the active compound is chemically identical. PMD is classified as a biopesticide by the EPA and has been commercially available as a mosquito repellent active ingredient since the early 2000s.
Key facts about PMD:
CAS Number: 42822-86-6. Derived from Corymbia citriodora (lemon eucalyptus). Chemical class: monoterpene diol. EPA-registered as a biopesticide. Also qualifies as an active ingredient in 25(b) exempt minimum risk pesticide products under FIFRA. CDC-recommended active ingredient since 2005. Effective against mosquitoes (Aedes, Anopheles, Culex, Ochlerotatus), ticks, biting flies, and gnats.
Important distinction: PMD/OLE is not the same as "lemon eucalyptus essential oil." The essential oil has not undergone validated efficacy testing and is not recommended by the CDC as a repellent. Only refined OLE or synthetic PMD products carry CDC endorsement.
What is DEET?
DEET (N,N-Diethyl-meta-toluamide) is a synthetic insect repellent developed by the U.S. Army in 1944 and registered for public use in 1957. It is the most widely used mosquito repellent active ingredient globally, with an estimated 8 billion applications over its history.
Key facts about DEET:
CAS Number: 134-62-3. Synthetic compound. Chemical class: toluamide. EPA-registered as a conventional pesticide. Available in concentrations from <10% to nearly 100%. CDC-recommended active ingredient. Effective against mosquitoes, ticks, fleas, chiggers, leeches, and biting flies. Known to damage certain plastics, synthetic fabrics, and finishes.
Effectiveness: PMD vs DEET — Head-to-Head
| Measure | PMD | DEET |
|---|---|---|
| Bite reduction | 90–95% reduction for 6–8 hours (at tested concentrations) | 90–97% reduction for 4–12 hours (concentration dependent) |
| Duration of protection | Up to 6 hours at 30% OLE; varies by formulation | Up to 6–12 hours; peaks at ~50% concentration |
| Mosquito species tested | Aedes aegypti, Ae. albopictus, Anopheles spp., Culex spp., Ochlerotatus spp. | Broad spectrum — all major mosquito genera |
| Tick repellency | Demonstrated in some studies; less data than for mosquitoes | Well-documented tick repellency |
| CDC assessment | Provides longer-lasting protection than other plant-based repellents | Typically provides longer-lasting protection than other active ingredients |
| Concentration note | Protection duration increases with concentration; 30–40% OLE performs comparably to low-to-moderate DEET | Efficacy peaks at ~50%; higher concentrations don't add meaningful protection time |
Summary: When comparing similar test conditions, PMD has demonstrated repellency comparable to DEET against key mosquito species. The 2006 Carroll & Loye review in the Journal of the American Mosquito Control Association concluded that the CDC endorsement of PMD was warranted and may even underestimate its value as a DEET alternative. However, DEET generally has a broader evidence base across more diverse field conditions and concentrations.
Key Clinical Studies
The following peer-reviewed studies form the evidence base for PMD's effectiveness as a mosquito repellent. All are published in indexed scientific journals.
| Study | Journal / Year | Key Finding |
|---|---|---|
| Carroll & Loye — "PMD, a registered botanical mosquito repellent with DEET-like efficacy" | J. Am. Mosq. Control Assoc., 2006 | Comprehensive review concluding PMD provides DEET-like efficacy across Aedes, Anopheles, Culex, and Ochlerotatus species. Endorsed CDC's 2005 recommendation. |
| Barnard et al. — "Repellency of IR3535, KBR3023, PMD, and DEET to Black Salt Marsh Mosquitoes" | J. Med. Entomol., 2002 | Field study in Everglades National Park. PMD achieved 89.2% mean repellency over 6 hours vs DEET's 94.8% — a comparable performance range. |
| Goodyer et al. — "Characterisation of actions of PMD repellent formulations against Aedes aegypti" | Trans. R. Soc. Trop. Med. Hyg., 2020 | 30% PMD showed similar half-life to 20% DEET (2.23 vs 2.74 hours). PMD-vanillin formulation achieved 1.5x longer complete protection time than 20% DEET. |
| Colucci & Müller — "Evaluation of standard field and laboratory methods to compare protection times of PMD and DEET" | Scientific Reports, 2018 | Compared standardized methods for evaluating PMD and DEET. Confirmed similar protection time profiles under controlled conditions. |
| Borrego et al. — "Effect of the Stereoselectivity of PMD Isomers on Repulsion toward Aedes albopictus" | J. Agric. Food Chem., 2021 | Identified (1R)-(+)-cis-PMD as the most active diastereomer, with repellent duration "very similar" to DEET when applied to skin. |
| Sangoro et al. — "Effect of PMD on Ae. aegypti blood feeding behavior and fecundity" | Tropical Medicine & Infectious Disease (PMC), 2018 | 20% PMD reduced Ae. aegypti blood-feeding by a statistically significant margin (p < 0.001). Studies indicated 90–95% bite reduction for 6–8 hours. |
Safety & Toxicity Comparison
| Safety Factor | PMD | DEET |
|---|---|---|
| Skin irritation | Possible eye and skin irritation, including allergic reactions. Generally well-tolerated. | Can cause skin irritation, rashes, and blistering in some individuals. One study of Everglades park employees found 25% reported negative effects from DEET exposure. |
| Neurological concerns | No documented neurological adverse effects at recommended use levels. | Sporadic reports of seizures, tremors, and encephalopathy with excessive use. Rat studies show neurotoxicity with prolonged high-dose exposure, especially combined with permethrin. Effects appear reversible. |
| Pregnancy safety | CDC considers EPA-registered PMD products safe during pregnancy. | CDC considers DEET safe during pregnancy. No adverse fetal effects found in studies of proper use. |
| Material damage | Does not damage plastics, synthetic fabrics, or finishes. | Can dissolve or damage plastics, rayon, spandex, some synthetic fabrics, and painted or varnished surfaces. |
| Acute toxicity (NFPA/HMIS) | Health: 0, Fire: 0, Reactivity: 0 (based on MSDS data) | Health: 1–2, Fire: 1, Reactivity: 0 (varies by formulation) |
| Environmental persistence | Readily biodegradable (OECD Modified Sturm Test). | Breaks down slowly in soil; detected in surface water and drinking water. Somewhat toxic to aquatic life. |
Important context: DEET has been used for over 60 years with a vast safety database. When used as directed, serious adverse effects are rare (estimated at roughly 1 in 100 million applications). Most documented cases of harm involve deliberate ingestion or extreme overuse. PMD has a shorter commercial history but a favorable safety profile with fewer reported adverse events.
Use with Children
| Age Group | PMD / OLE | DEET |
|---|---|---|
| Under 2 months | ❌ Not recommended. Use mosquito netting. | ❌ Not recommended. Use mosquito netting. |
| 2 months – 3 years | ❌ CDC recommends against OLE/PMD for children under 3 due to potential allergic skin reactions. However, certain products containing OLE as their sole active ingredient at ≤30% concentration may be used — always read the product label. | ✅ Can be used. AAP recommends no more than 30% DEET for children. Apply sparingly; avoid hands and face. |
| 3 years and older | ✅ Can be used as directed. | ✅ Can be used as directed. |
Note on The Superbloc products: The Superbloc's personal care repellents contain 8% PMD and are formulated as 25(b) exempt minimum risk pesticides under FIFRA. They are labeled as safe for use on children 6 months and older. This differs from the CDC's general OLE/PMD guidance because 25(b) exempt products have a separate regulatory framework. Always follow the specific product label instructions.
Environmental Impact
PMD is readily biodegradable according to OECD testing methods. Products formulated with PMD have been determined to pose no hazard to air, water, aquatic life, or humans in disposal testing. PMD is not classified as hazardous by DOT and has no UN transport restrictions.
DEET has been detected in surface water, groundwater, and drinking water due to incomplete removal at wastewater treatment facilities. It breaks down slowly in soil and very slowly in sediment. DEET has been shown to be somewhat toxic to certain aquatic organisms, though environmental concentrations are typically low.
CDC & Regulatory Positions
CDC (Centers for Disease Control and Prevention): In 2005, the CDC added PMD (via OLE) to its list of recommended mosquito repellent active ingredients. The current CDC Yellow Book (2026 edition) lists PMD alongside DEET, picaridin, IR3535, and 2-undecanone as recommended options. The CDC notes that OLE provides longer-lasting protection than other plant-based repellents.
EPA (Environmental Protection Agency): Both PMD and DEET are EPA-registered active ingredients. PMD is classified as a biopesticide. PMD also qualifies as an active ingredient in 25(b) exempt minimum risk pesticide products, which are exempt from EPA registration requirements.
Health Canada: Has capped DEET concentrations at 30% for consumer products based on a human health risk assessment considering daily prolonged application. OLE/PMD products are available in Canada.
EWG (Environmental Working Group): Recommends repellents with picaridin, DEET (at 7–30%), IR3535, or OLE (at 30–40%) as effective options. Lists OLE/PMD as a viable alternative for consumers seeking plant-derived options.
Choosing the Right Repellent for Your Situation
| Scenario | Consider |
|---|---|
| Everyday outdoor activities (backyard, parks, walks) | PMD-based products offer effective protection with a pleasant scent and gentler profile for daily use. |
| High-risk disease areas (tropical travel, endemic zones) | DEET at 20–30% or picaridin for maximum duration; PMD at higher concentrations (30%+) also appropriate. |
| Families with young children (6 months – 3 years) | DEET at low concentrations (per AAP) or 25(b) exempt PMD products labeled for the appropriate age range. Always read product labels. |
| Sensitive skin or chemical sensitivities | PMD-based, alcohol-free formulations with skin-soothing ingredients (aloe, chamomile) tend to cause less irritation. |
| Protecting gear and clothing | PMD does not damage plastics or synthetics. DEET can damage these materials. Consider permethrin-treated clothing as a supplement. |
The Superbloc uses PMD in every personal care product 🌿
Our Bloc Off and Bloc & Chill lines feature 8% PMD from lemon eucalyptus, lab-tested for 6+ hours of protection. DEET-free. Alcohol-free. Infused with aloe vera and chamomile. Safe for babies 6 months and up.
Shop The Superbloc →References
- Carroll SP, Loye J. "PMD, a registered botanical mosquito repellent with DEET-like efficacy." J Am Mosq Control Assoc. 2006;22(3):507-14. PubMed 17067054
- Barnard DR, Bernier UR, Posey KH, Xue RD. "Repellency of IR3535, KBR3023, para-menthane-3,8-diol, and DEET to Black Salt Marsh Mosquitoes in the Everglades National Park." J Med Entomol. 2002;39(6):895-899. DOI: 10.1603/0022-2585-39.6.895
- Goodyer L, et al. "Characterisation of actions of p-menthane-3,8-diol repellent formulations against Aedes aegypti mosquitoes." Trans R Soc Trop Med Hyg. 2020;114:687. PubMed 32542324
- Colucci B, Müller P. "Evaluation of standard field and laboratory methods to compare protection times of the topical repellents PMD and DEET." Sci Rep. 2018;8:12578. DOI: 10.1038/s41598-018-30998-2
- Borrego LG, et al. "Effect of the Stereoselectivity of para-Menthane-3,8-diol Isomers on Repulsion toward Aedes albopictus." J Agric Food Chem. 2021;69(37):11095-11109. DOI: 10.1021/acs.jafc.1c03897
- Sangoro PO, et al. "Effect of the Topical Repellent para-Menthane-3,8-diol on Blood Feeding Behavior and Fecundity of Ae. aegypti." Trop Med Infect Dis. 2018;3(2):72. PMC 6023277
- CDC Yellow Book 2026. "Mosquitoes, Ticks, and Other Arthropods." Connelly CR, Gimnig JE. April 23, 2025. CDC.gov
- Bloomquist JR, Swale DR. "Is DEET a dangerous neurotoxicant?" Pest Manag Sci. 2019. PubMed 31069958
- ATSDR. "Toxicological Profile for DEET." Agency for Toxic Substances and Disease Registry. ATSDR.cdc.gov
- EPA. "p-Menthane-3,8-diol (011550) Fact Sheet Summary." EPA.gov
- NPIC. "Insect Repellents Fact Sheet." National Pesticide Information Center, Oregon State University. NPIC.orst.edu
- EWG. "Guide to Bug Repellents." Environmental Working Group. EWG.org
About The Superbloc: The first brand dedicated entirely to plant-based bug solutions. Our products use PMD as the active ingredient and are formulated as 25(b) exempt minimum risk pesticides under FIFRA. Women-founded. Stocked at Anthropologie. Featured in Goop and Harper's Bazaar. For questions about this resource, contact hello@thesuperbloc.com.
Last updated: March 2026. This page is reviewed and updated periodically as new research becomes available.