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Does Bug Spray Expire? What EPA's Label Rules Actually Require

By Andrew Rothaus, Founder ·

Short answer: EPA requires a "Not for sale or use after [date]" statement only where a formulation is determined to change chemical composition significantly. Where a date is printed, the product must meet all label claims up to it. Where none is printed, storage conditions decide how fast it degrades.

Three amber bottles on a sunlit shelf, the kind of half-used repellent that sits in a cabinet for years

Does bug spray have an expiration date at all?

Only when EPA has determined the formulation changes chemical composition significantly, and the reason is one conditional sentence in federal pesticide labeling law. The rule at 40 CFR 156.10 reads: "In cases where it is determined that a pesticide formulation changes chemical composition significantly, the product must bear the following statement in a prominent position on the label: 'Not for sale or use after [date].'" That determination is the trigger. No such requirement applies otherwise, which is why a bottle can show an EPA Reg. No. and no date.

When a date is printed, it means something specific: the same section says the product must meet all label claims up to the expiration time indicated on the label.

What every registered repellent shows instead is a registration number and a storage block. The label must carry its registration number preceded by "EPA Registration No." or "EPA Reg. No.", and its storage and disposal instructions must be grouped under the heading "Storage and Disposal."

What does EPA test before a repellent goes on sale?

Storage stability, and it is not optional. EPA's product chemistry data requirements table at 40 CFR 158.310 lists test guideline 830.6317, storage stability, with an R for both MP and EP. In the table's key, R means required, MP means manufacturing-use product and EP means end-use product.

EPA's 2012 news story describes the study it streamlined as a one-year study required to fulfill the agency's data requirements for pesticide registration and re-evaluation. EPA's accelerated alternative tests pesticides at an elevated temperature of 54 degrees C, which EPA said makes it unsuitable for some products and materials. If a 14-day study demonstrates product instability, a full one-year study is required.

Purdue University's Pesticide Programs, in a bulletin written for pesticide applicators, puts it plainly: the concentration of the active ingredient must remain stable when stored under conditions that simulate two years of real-time aging, and EPA requires the product to remain physically stable for two years, meaning it does not irreversibly clump or separate. Those are Purdue's words, not an EPA statement.

How long is bug spray good for?

It depends on how it has been stored, and none of the agency or university sources this article draws on, EPA, NPIC or Purdue, gives a number. Purdue's bulletin says why: storage conditions greatly influence how fast a product degrades, so there is no set time for the long-term stability of pesticide formulations. What it depends on, per Purdue: formulation, active ingredient, age, storage conditions, and whether the container remained sealed or was opened.

Purdue also separates two terms people blur. Purdue says manufacturers set expiration dates, and that an expiration date tells you a properly stored product will perform as expected if you use it before that date. Shelf life, in Purdue's terms, is how long the product will remain effective after its expiration date and warranty have passed.

Sawyer, on its FAQ page, says its insect repellents have a shelf life of 10 or more years when properly stored in a cool, dry location away from direct UV exposure. That is Sawyer's statement about Sawyer's repellents, and Purdue notes that manufacturers make no assurances or warranties about the quality of their products after the expiration date.

Does bug spray work after the expiration date?

Possibly, and Purdue's Pesticide Programs bulletin is blunt about the uncertainty: a pesticide product used beyond its expiration date may or may not be less effective. It has not necessarily degraded to the point that it is no longer effective, and, in Purdue's words, there is no guarantee that it has not degraded.

While the date was valid, the product had to meet all label claims up to the expiration time indicated on the label. EPA notes that even between registered products, protection times vary because of differences in the testing conditions. Past the date, Purdue notes, manufacturers make no assurances or warranties about the quality of their products.

What happens if you use expired insect repellent?

Possibly a weaker product, or one that dispenses badly. Purdue's Pesticide Programs bulletin says a pesticide product used beyond its expiration date may or may not be less effective, and that products used beyond their shelf life may suffer dispensing problems, loss of potency, or spray application difficulties. Purdue's list is written for pesticide applicators generally, not for any particular can of repellent.

The concern is performance. EPA's guidance for repellents is to read the product label before using it and to apply and re-apply according to the label instructions, with a warning: if you don't follow the label directions, the product may not be as effective as you expect. Storage directions are label directions too.

Does bug spray go bad in heat or if it freezes?

Yes, both. NPIC, the National Pesticide Information Center, says extremes in temperature can change the chemistry of some pesticides inside the container.

Heat is the case the testing anticipates. EPA's accelerated protocol tests pesticides at an elevated temperature of 54 degrees C. Separately, Purdue's bulletin puts the scale of heat aging in everyday terms: accelerated testing at 122 degrees F for two weeks normally predicts about two years of ambient storage stability. A trunk does not run a controlled two-week test; it runs all summer.

Freezing is the case people forget. Purdue describes what can happen to a pesticide product subjected to freezing temperatures: the active ingredient could crystallize and fall out of suspension, settle to the bottom, and not resuspend when thawed and remixed. Purdue means pesticide formulations broadly, not any specific repellent.

How long is bug spray good for once opened?

None of the agency or university sources this article draws on, EPA, NPIC or Purdue, gives an after-opening window. Purdue lists whether a container remained sealed or was opened as one factor among several, alongside formulation, active ingredient, age and storage conditions.

Sawyer has gone on record for its own line. Sawyer's FAQ says opening the bottle has no effect on the shelf life of its insect repellents. That is Sawyer speaking about Sawyer products.

Does DEET expire? Does picaridin?

The expiration rule attaches to the finished product, not to the active ingredient in it. Products built on DEET or picaridin sit under the same 40 CFR 156.10 rule described above: a date only where the formulation is determined to change chemical composition significantly, and all label claims met up to any date that is printed.

What the chemistry sources say is narrower than "does not expire." NPIC's technical fact sheets, in their environmental-fate sections, report that picaridin is stable to hydrolysis under environmentally relevant conditions, and that DEET, at soil pH levels typically found in the environment, is stable to hydrolysis. Those are environmental-fate findings, not shelf-life data for a bottle in a cabinet. How long picaridin lasts on skin once applied is a different question; the two actives side by side are at picaridin vs DEET, and our DEET evidence review covers what the EPA reviews say.

For a specific branded DEET spray, the answer is on the can: find the EPA Reg. No., which the label must carry, then look for a "Not for sale or use after" line.

Does the format matter: aerosol, pump, lotion or wipe?

Yes, because the label time belongs to the product that carries it. EPA says an EPA registration number on a repellent label means the company provided EPA with technical information on the effectiveness of that product. EPA's repellency awareness graphic, where a product carries it, shows numbers that represent typical protection times, and those vary between products because of differences in the testing conditions.

Sawyer compares formats within its own line. Sawyer's FAQ says that because of the way they slow down the evaporation of the product, lotions will last approximately two hours longer than sprays of comparable concentrations. That is Sawyer's statement about its own line. Where "how long does it last" means wash cycles on treated clothing, see our permethrin clothing guide.

How do you store repellent so it lasts?

In the container it came in, with the label on, between 40 and 90 degrees F, away from anything that can ignite it, and out of reach of children. EPA says to always store pesticides in their original containers with the label, which lists directions for use, ingredients, and first aid steps in case of accidental poisoning. NPIC adds that the original container is designed to protect the product and is made of materials that will withstand the chemicals in it.

NPIC says to always read the label for storage instructions and, as a general rule, that pesticides are best stored between 40 and 90 degrees F. EPA adds that flammable liquids belong outside your living area and far away from an ignition source such as a furnace, car, grill or lawn mower. Check the gear bin in the garage against both.

For households with children, EPA says to store insect repellents out of the reach of children, in a locked utility cabinet or garden shed. Our guide to mosquito repellent for kids covers the age rules.

How do you get rid of old bug spray?

Follow the label first, then your local rules. EPA's disposal guidance opens with: follow all disposal instructions on the pesticide label. The Storage and Disposal block is where those live.

For leftovers, both EPA and NPIC point to household hazardous waste. EPA says to check with your local solid waste management authority, environmental agency or health department for a household hazardous waste collection program or a similar program for unwanted, leftover pesticides. NPIC is stricter: if any product remains in the container, it must be disposed of as household hazardous waste. EPA also notes that state and local pesticide disposal laws may be stricter than the federal requirements on the label.

And the bottle you cannot place at all? EPA's storage guidance names two conditions: you can't identify the contents of the container, or you can't tell how old the contents are. For that bottle, the guidance above applies: the label's disposal instructions first, and household hazardous waste for anything left in it.

Common questions

Is expired insect spray still usable?

Possibly, with no guarantee. Purdue's Pesticide Programs bulletin says a pesticide product used beyond its expiration date may or may not be less effective: it has not necessarily degraded to the point of being ineffective, and, in Purdue's words, there is no guarantee that it has not degraded. Past the date, you are using it on your own judgment.

Does bug spray go bad in the heat?

It can. NPIC says extremes in temperature can change the chemistry of some pesticides inside the container, and that as a general rule pesticides are best stored between 40 and 90 degrees F, with the label as the first place to check for storage instructions. A summer in a parked car sits well outside a cool, dry place.

How long is bug spray good for once opened?

None of the agency or university sources this article draws on, EPA, NPIC or Purdue, gives an after-opening window. Purdue's Pesticide Programs bulletin lists whether a container remained sealed or was opened as one factor among several in how long a pesticide lasts in storage, alongside formulation, active ingredient, age and storage conditions.

Can I throw old bug spray in the trash?

Not with product still in it. NPIC says that if any product remains in the container, it must be disposed of as household hazardous waste, and EPA says to check with your local solid waste management authority, environmental agency or health department for a household hazardous waste collection program. For an empty container, follow the label's Storage and Disposal block.

About Longsleeve

Longsleeve is an EPA-registered picaridin lotion (EPA Reg. No. 101457-1). It repels mosquitoes and ticks for up to 14 hours. Its label's storage directions: store in a cool, dry place out of the reach of children, away from heat, sparks and open flame.

Sources

  1. eCFR, 40 CFR 156.10 Labeling requirements. https://www.ecfr.gov/current/title-40/chapter-I/subchapter-E/part-156/subpart-A/section-156.10
  2. US EPA Label Review Manual, Chapter 13: Storage and Disposal (July 2013). https://www.epa.gov/sites/production/files/2017-10/documents/chap-13-jul-2013.pdf
  3. eCFR, 40 CFR 158.310 Product chemistry data requirements table. https://www.ecfr.gov/current/title-40/chapter-I/subchapter-E/part-158/subpart-D/section-158.310
  4. US EPA archived pesticide news story, New Protocol Streamlines Development of Storage Stability and Corrosion Characteristics Studies for Some Pesticides (November 30, 2012). https://archive.epa.gov/oppfead1/cb/csb_page/updates/2012/web/html/storage-stab.html
  5. Purdue University Pesticide Programs PPP-142, Is This Pesticide On My Shelf Still Good? https://ag.purdue.edu/department/extension/ppp/resources/ppp-publications/mobile/ppp-1421.html
  6. Sawyer Products FAQs. https://www.sawyer.com/faqs
  7. US EPA, Find the Repellent that is Right for You. https://www.epa.gov/insect-repellents/find-repellent-right-you
  8. US EPA, Using Insect Repellents Safely and Effectively. https://www.epa.gov/insect-repellents/using-insect-repellents-safely
  9. National Pesticide Information Center, Storage of Pesticides. http://npic.orst.edu/health/storage.html
  10. US EPA, Storing Pesticides Safely. https://www.epa.gov/safepestcontrol/storing-pesticides-safely
  11. National Pesticide Information Center, Picaridin Technical Fact Sheet. http://npic.orst.edu/factsheets/archive/Picaridintech.html
  12. National Pesticide Information Center, DEET Technical Fact Sheet. http://npic.orst.edu/factsheets/archive/DEETtech.html
  13. US EPA, Repellency Awareness Graphic. https://www.epa.gov/insect-repellents/repellency-awareness-graphic
  14. US EPA, Safe Disposal of Pesticides. https://www.epa.gov/safepestcontrol/safe-disposal-pesticides
  15. National Pesticide Information Center, Disposal of Pesticides. http://npic.orst.edu/health/disposal.html

Last reviewed 2026-09-09 · every claim on this page is sourced above