Published May 30, 2023 • Updated May 27, 2026
Reviewed by Julie Miller, BA in Language Arts, Editorial Lead, Dr. Killigan’s
TL;DR: Pyrethrin and permethrin are both insecticides, but they differ in origin, environmental behavior and residual performance. Pyrethrins are plant-derived compounds extracted from chrysanthemum flowers, while permethrin is a synthetic pyrethroid formulated for more persistent activity after application.
In this guide, we’ll compare pyrethrins, pyrethroids and permethrin side by side—including how they work, where they’re commonly used and why residual synthetic insecticides are a growing concern for many households.
Pyrethrin vs permethrin: Key differences
Here’s a clear breakdown of how they compare.
Source: Pyrethrins originate from chrysanthemum flowers. Permethrin is produced through chemical manufacturing.
Environmental behavior: Pyrethrins break down quickly when exposed to sunlight, oxygen and moisture. Permethrin is more stable and can remain active longer on treated surfaces, fabrics and other materials.
Classification: Permethrin is a pyrethroid— synthetic compound developed from the chemistry of natural pyrethrins.
Common uses: Pyrethrins are commonly used in contact sprays, foggers and select personal-care insect treatments. Permethrin is used in treated clothing, agricultural insecticides, mosquito-control applications and some lice products, depending on the formulation and label.
What are pyrethrins?
Pyrethrins are a group of botanical insecticides known for their rapid knockdown effect against insects such as fleas, flies, mosquitoes and moths. These compounds have been widely used in household and agricultural pest control because they act quickly on the insect nervous system.
Pyrethrins work by disrupting sodium channel function in insect nerve cells. This interferes with normal nerve signaling, causing overstimulation, paralysis and death.
What are pyrethroids?
Pyrethroids are synthetic insecticides developed from the model of natural pyrethrins. They were designed to keep the insect-killing effect while improving stability after exposure to light, oxygen and other environmental factors.
Is permethrin a pyrethroid?
Yes. Permethrin belongs to the pyrethroid class.
Other pyrethroids include resmethrin, cypermethrin, deltamethrin, lambda-cyhalothrin, bifenthrin, cyfluthrin, esfenvalerate, allethrin and tetramethrin.
Pyrethrum vs pyrethrin vs permethrin
Pyrethrum, pyrethrin and permethrin are related terms, but they refer to different levels of classification.
- Pyrethrum is the crude extract sourced from chrysanthemum flowers.
- Pyrethrins are the naturally occurring insecticidal compounds found within that extract.
- Permethrin is a synthetic compound.
In short: pyrethrum is the source extract, pyrethrins are the active natural compounds and permethrin is a synthetic pyrethroid inspired by those compounds.
Which is more commonly used?
Pyrethroids are more widely used than pyrethrins.
In large-scale agricultural, structural and public health settings, pest control decisions account for cost, coverage area, application method and how long a treatment remains useful. These practical factors help explain why pyrethroids are common in modern pest control.
Are pyrethrins safe?
Pyrethrins are generally considered to have low toxicity to humans and pets when used according to label directions. However, some individuals may experience allergic reactions or sensitivity depending on exposure conditions. Safety also depends on the full formulation, particularly when synergists are added to increase insecticidal performance.
An example is piperonyl butoxide (PBO), a synergist commonly added to pyrethrin products. It works by interfering with the enzymes insects use to process and neutralize toxic compounds, allowing the insecticide to remain active longer. This mechanism affects biological processes not solely unique to insects.
In other words, the safety conversation should look beyond the word “pyrethrin” on a label.
Even plant-derived insecticides can have tradeoffs. Pyrethrins can be toxic to aquatic organisms, particularly fish and aquatic invertebrates. Avoid applying them near creeks, ponds, storm drains or anywhere runoff may carry product into waterways. Always follow the label to reduce exposure risks.
Exposure dynamics and systemic effects
According to the nonprofit Beyond Pesticides, PBO may affect the body’s ability to process certain compounds, raising concerns about respiratory irritation. Toxicological literature has reported that inhalation exposure can be associated with labored breathing and fluid buildup in the lungs.
Because of its widespread use, researchers have also examined population-level exposure patterns. A 2024 analysis cited by Beyond Pesticides detected PBO in 100% of hair samples from over 200 children in France, along with biomarkers indicating exposure to multiple other pesticides. (Biomarkers are measurable chemical traces left in the body after pesticide contact).
Emerging toxicology research
Current toxicology research is examining how early-life exposure to PBO may affect biological pathways involved in brain and developmental growth. A 2020 study published in Chemosphere found that PBO can disrupt the Sonic hedgehog (Shh) signaling pathway, which is critical for embryonic brain and facial development.
In animal models, in utero exposure was associated with craniofacial malformations and neurodevelopmental abnormalities. While direct human evidence remains limited, these findings suggest a potential link between prenatal exposure and developmental effects in children.
Other commonly used synergists include sesamex and MGK-264.
Are pyrethroids safe?
Pyrethroid safety depends on the compound, formulation, exposure route and frequency of use. Because pyrethroids are common in residential environments, researchers have studied how low-level, repeated exposure may show up in real-world populations.
Pyrethroids are often marketed as a safer alternative to older pesticide classes such as organophosphates. But safer than something more hazardous does not mean risk-free. Pyrethroids are neurotoxic by design, targeting the insect nervous system.
What does real-world exposure look like?
A 2014 study published in Environmental Science & Technology (ACS Publications) analyzed 90 families in northern California and detected pyrethroid metabolites in urine samples, including TCPy (trichloropyridinol), a breakdown product associated with several common pyrethroid insecticides.
Children in the study showed higher metabolite levels than national averages reported by NHANES (2001–2002).
Many of the families included in the study were living in homes where pyrethroids had been applied for indoor pest control. This suggests a disproportionate exposure burden in residential settings—exactly where children spend the most time.
In other words, exposure is not limited to direct spraying or application events. It can also occur through routine contact with treated indoor surfaces, where residues may remain present after use.
What health outcomes are being studied?
Research on pyrethroid exposure has identified early-life and long-term exposure patterns.
- A review highlighted by Beyond Pesticides reported associations between higher pyrethroid exposure and developmental delays in children, including cognitive and motor impacts observed in multiple studies. One study found that children with higher exposure levels were three times as likely to experience mental delays compared to those with lower exposure.
- A 2020 study published in The Lancet Diabetes & Endocrinology found that prenatal exposure to certain pyrethroids may interfere with thyroid hormone activity, which is essential for normal fetal brain and nervous system development. This disruption may increase the risk of intellectual delays in infants.
- Findings summarized by The National Library of Medicine have linked occupational exposure to reproductive effects, including reduced fertility, adverse pregnancy outcomes and, in some studies, associations with outcomes such as preterm birth, small-for-gestational-age births and stillbirth.
- Research published in Environmental Health Perspectives has documented elevated pyrethroid residue levels in high-density, poorly maintained urban housing, including settings such as New York City. This suggests an environmental exposure disparity, where living conditions may influence the degree of everyday pesticide exposure.
What do researchers conclude?
Current research shows consistent associations between pyrethroid exposure and potential developmental, reproductive and endocrine effects under specific exposure conditions.
This is reinforced by population-level data from a study led by Youssef Oulhote, published in Environmental Health Perspectives, showing that urinary metabolites—breakdown products of pyrethroid insecticides processed by the body—were detected in nearly all children tested.
A hidden presence in everyday products
Pyrethrins, pyrethrum and pyrethroid-based insecticides are found in more places than many people realize. They show up in household foggers, flea treatments, yard sprays and automatic pest control systems used for insects like mosquitoes, flies, moths, ants, fleas and lice.
Synthetic pyrethroids also appear widely in longer-lasting pest control treatments, including those used for cockroaches, termites, ticks, bed bugs and scabies mites.
Taken together, these compounds are embedded across everyday pest control routines—from quick home treatments to more persistent, large-scale applications—often blending into the background of routine household use.
Why choose Dr. Killigan’s?
Pyrethroids are widely used in modern pest control—but they are not the only way to manage insects in and around the home.
Dr. Killigan’s is committed to being pyrethroid-free. Our current products are also pyrethrin-free. We focus on plant-powered and mechanical-kill solutions designed to help protect your home without synthetic pyrethroids or harsh chemical residues.
Our products are designed to give families a more considered way to manage pests—one that supports Confidence, Peace and Control without relying on conventional pesticide residues many households prefer to avoid.
Dr. Killigan’s products are classified as FIFRA 25(b) minimum-risk pest products under U.S. law, meaning they are made with ingredients recognized by the U.S. EPA as posing little to no risk to human health and the environment when used as directed.
Pyrethrins and pyrethroids can kill bugs—but so can we. We simply take a different path.
Dr. Killigan’s plant-powered pest control
Here are three standout pest control solutions. For the full lineup, visit our shop page.
Six Feet Under kills more than 60 insect species on contact and continues working for up to 30 days. Powered by cinnamon and clove essential oils, this plant-powered insect spray is designed for use around entry points, baseboards and other high-traffic areas.
Pantry Moth Traps and Clothing Moth Traps use Dr. Killigan’s Blue Stripe Formula, a double-potent pheromone lure that works with moth biology rather than broad synthetic insecticides. These mechanical-kill traps attract and capture adult male moths, helping disrupt the reproductive cycle in food storage and closet environments.
Barricade creates a long-lasting barrier around your home, protecting against 50+ common household pests for up to 90 days. Powered by peppermint oil and soybean oil, Barricade uses a mechanical-kill method that penetrates insects’ exoskeletons, helping prevent resistance without synthetic pyrethroid residues or routine service calls.
Explore more
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The truth about pesticide labels: What you need to know, not fear
(How to read beyond front-label claims and understand active ingredients, precautionary statements and environmental warnings.) -
Ingredients without harmful pesticides: Understanding EPA’s “minimum risk pesticides”
(What FIFRA 25(b) means, how minimum-risk ingredients are classified and why label transparency matters.) -
The hidden impact of pesticides on human health
(A closer look at how pesticide exposure is studied and why formulation, frequency and environment matter.) -
Dr. Killigan’s: Safe for families, lethal for insects
(How Dr. Killigan’s approaches pest control with plant-powered and mechanical-kill solutions designed for the home.)
