The label is the law. Read your product's label before you mix or apply; the rates here come from the labels listed under Sources.
- Active ingredient
- Piperonyl butoxide (CAS 51-03-6)
- Chemical class
- Pesticide synergist, usually combined with natural pyrethrins or synthetic pyrethroids.[1]
- Mode of action
- Synergist: not insecticidal on its own; blocks insect enzymes that break down insecticides[1]
- Signal word
- Crossfire Bed Bug Concentrate (contains 10% PBO): none required[2]
How a synergist works
Early studies found PBO greatly improved how well pyrethrins killed house flies even though PBO alone didn't kill them, letting smaller amounts of pyrethrins do the job.[1]
Where it is used
You'll find it in foggers, dusts and sprays for homes, in agricultural and livestock products, in mosquito control programs and in pet flea and tick treatments.[1]
Some head lice lotions and shampoos contain PBO; those are regulated by the FDA, not as pesticides.[1]
Because PBO is always combined with an insecticide, exposure precautions come from the other active ingredient's label.[1]
Products and registrations
| Product | Registrant | EPA Reg. No. | Active % | Formulation | Signal word |
|---|---|---|---|---|---|
| Crossfire Bed Bug Concentrate (contains 10% PBO)[2] | Sumitomo BioRational Company, LLC (MGK) | 1021-2776 | 14.1% | water-dilutable concentrate | none |
Label rates
| Product | Use | Pests | Rate |
|---|---|---|---|
| Crossfire Bed Bug Concentrate (contains 10% PBO) | Indoor bed bug treatment (Crossfire, PBO with clothianidin and metofluthrin) | Bed bugs | 13 fl oz concentrate per gallon of finished spray (treats 1,000 sq ft)[2] PBO is never used alone, so its rate is set by the product it is in; this example is Crossfire, where the finished spray is 1% PBO. |
Safety and environmental hazards
People
NPIC rates PBO low to very low in toxicity if eaten, inhaled or touched; it is slightly irritating to eyes and skin and doesn't cause skin allergies. EPA classifies it as a possible human carcinogen based on high-dose animal studies; IARC calls it not classifiable.[1]
Pets
PBO is registered in flea and tick treatments for dogs and cats; follow the label of the specific product.[1]
Bees and pollinators
PBO by itself is practically non-toxic to bees, but it is usually combined with pyrethrins or pyrethroids that are toxic to bees.[1]
Fish and water
PBO is moderately to highly toxic to aquatic invertebrates such as water fleas and shrimp.[1]
Common questions
- Is PBO an insecticide?
- It is registered as an active ingredient but is a synergist: by itself it isn't designed to harm insects.[1]
- Is piperonyl butoxide safe for bees?
- NPIC says PBO alone is practically non-toxic to bees, but the insecticides it's paired with often are toxic to bees.[1]
- Does PBO stay in the body?
- In animal studies most PBO left the body within 48 hours; in human volunteers about 2% of a skin dose was absorbed in 30 minutes.[1]
Sources
- National Pesticide Information Center, “Piperonyl Butoxide (PBO) General Fact Sheet.” npic.orst.edu/factsheets/pbogen.html (accessed 2026-10-06)
- U.S. EPA Pesticide Product Label System, “Crossfire Bed Bug Concentrate (VBC3 Insecticide) label, EPA Reg. No. 1021-2776 (EPA-stamped, Feb. 5, 2020).” www3.epa.gov/pesticides/chem_search/ppls/001021-02776-20200205.pdf (accessed 2026-10-06)