p-Menthane-3,8-diol
Cyclohexanemethanol, 2-hydroxy-.alpha.,.alpha.,4-trimethyl-
What is PMD?
PMD is the active molecule inside oil of lemon eucalyptus, and the only plant-derived repellent compound with DEET-class evidence. At 30%-OLE-equivalent concentrations it provides 4–6 hours of complete mosquito protection.
When to choose it: Same niche as OLE: serious plant-derived mosquito protection. Not for children under 3.
The active molecule inside oil of lemon eucalyptus, and the one plant-derived compound that tests in DEET's range against mosquitoes. Directly synthesized and plant-refined PMD are the same molecule and perform the same.
How it works
PMD masks the carbon-dioxide and skin-odor cues mosquitoes home in on, the same broad approach as DEET and picaridin rather than the brief contact deterrence of most plant oils.
Safety around dogs & cats
Refined PMD is low-toxicity in mammals, but it is a menthane terpenoid, and cats clear terpenes slowly, so a cat that grooms a treated surface can drool or be briefly wobbly. Keep it off pets and let treated skin dry before contact; pet-specific data are limited.
Low confidence. Ratings from ASPCA Animal Poison Control, the Pet Poison Helpline, and published veterinary toxicology. This is general information, not veterinary advice. If your pet is exposed, call your vet or the ASPCA Animal Poison Control Center at (888) 426-4435.
Mosquito protection by concentration: p-Menthane-3,8-diol
Complete protection time (dark = lower bound, light = upper bound) on the same 12 h scale used across the site. Modeled from published dose-response data in our research library.
The evidence
A 2018 comparison found 15% PMD comparable to 15% DEET across three mosquito species in cage and field tests, and field trials in Senegal (2009) and across multiple mosquito genera (2006) agree. Its weak point is ticks, where the only skin-protection data come from a single sponsor-reported trial.
- Complete Protection Time of a 30% Citriodiol (oil of lemon eucalyptus) repellent against three species of ticks (ARCTEC trial, NCT03708120)2019RctLimited evidence
A sponsor-run trial (registered as NCT03708120) measuring how long a consumer 30% Citriodiol spray, the refined oil-of-lemon-eucalyptus active, protects skin against three tick species. It is the only skin complete-protection-time tick study for OLE, but its results were never independently published.
- Evaluation of standard field and laboratory methods to compare protection times of the topical repellents PMD and DEET2018Field TrialWell-supported evidence
An open-access study asking a methodological question: how well do laboratory arm-in-cage tests predict real-world field protection? It tested identical 15% PMD and 15% DEET solutions on the same volunteers in both settings.
- Efficacy of four insect repellents against mosquito bites: a double-blind randomized placebo-controlled field study in Senegal2009RctDefinitive evidence
A double-blind field trial in two Senegalese villages, run at peak biting season, testing four real repellents against a look-alike placebo lotion under heavy wild-mosquito pressure: 20% picaridin, 20% and 50% PMD (the lemon-eucalyptus active), and 50% DEET. Volunteers applied a product to one bare lower leg and caught every mosquito that landed over an evening.
- PMD, a Registered Botanical Mosquito Repellent with Deet-Like Efficacy2006Field TrialWell-supported evidence
Carroll and Loye's case that PMD, the refined lemon-eucalyptus active, performs like DEET and deserved its 2005 CDC endorsement. It combines a review of PMD across mosquito genera with the authors' own field and lab trials.
Products using it
OFF!
OFF! Botanicals Insect Repellent
p-Menthane-3,8-diol 10%
Complete protection
OFF!
OFF! Botanicals Towelettes
p-Menthane-3,8-diol 8%
Complete protection
Not recommended
Potentially not EPA compliant
The Superbloc
The Superbloc Bloc & Chill Mosquito Repellent Spray
Oil of Lemon Eucalyptus 1% · Cedarwood oil 0.5%
Complete protection
Not recommended
Potentially not EPA compliant
The Superbloc
The Superbloc Bloc Off Mosquito Repellent Spray
Oil of Lemon Eucalyptus 1% · Cedarwood oil 0.5%
Complete protection
Not recommended
Potentially not EPA compliant
The Superbloc
The Superbloc Bloc & Chill Mosquito Repellent Wipes
Oil of Lemon Eucalyptus 1% · Cedarwood oil 0.5%
Complete protection
Common misconceptions
Myth: “Synthesized PMD is inferior to the plant version.”
Reality: The molecule is the molecule. Synthesized PMD performs equivalently to plant-refined OLE at the same concentration, and both are EPA-registered.
Regulatory notes
Source: EPA SRS active ingredient list export. Minimum risk (25(b)) status is applied separately when applicable.
Safety notes
Registered and CDC-endorsed against mosquitoes, but not for children under 3. Standardized PMD is not interchangeable with raw lemon-eucalyptus essential oil, which is neither registered nor tested the same way.
Frequently asked questions
Is PMD natural or synthetic?
Both exist: it occurs in refined lemon eucalyptus oil and is also synthesized directly. Performance is equivalent at equal concentrations.
How does PMD compare to DEET?
A 2018 protection-time comparison found 15% PMD comparable to 15% DEET in standardized testing, a result unique among plant-derived actives.