The arrival of warmer weather brings a lot of exciting things, including longer days, backyard barbecues, and trips to the beach. But one thing no one is looking forward to when temperatures begin to rise is bugs. The pesky critters do everything from bite and sting to swarm around your food. That's why it helps to have some sort of insect repellent handy to keep mosquitoes, flies, and other unwelcome bugs at bay. If you still have a stray bottle or two at home from last summer, you may be wondering: Does bug spray expire? Though insect repellent may not have a listed expiration date, the summer staple does lose its effectiveness over time. Ahead, we talked to pest experts who answer all our questions about old insect repellent.
- Timothy Wong, technical director ofM&M Pest Control
- Nichole Powell, founder and CEO of Kinfield, a company that creates all-natural products for the outdoors, including repellent
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Do Insect Repellents Expire?
Bug sprays can lose some of their peak effective repelling qualities as time goes on, but most bug sprays don't actually have an expiration date listed on the bottle. "Bug sprays registered by the EPA aren't required to have labeled expiration dates as long as the formulation is stable for at least one year, which most are," says Timothy Wong, technical director ofM&M Pest Control. "As for bug sprays that don't require registration (i.e., the ones that use essential oils as their active ingredients), there are no federal laws requiring them to have expiration dates either."
:max_bytes(150000):strip_icc()/GettyImages-1265287553-0ca0948aa26f4d5685af2dc18027348e.jpg "Does Bug Spray Expire? Here's How to Know If Last Year's Repellent Is Still Effective (1)")
How Long Bug Spray Lasts
On the higher end, bug spray with DEET or picaridin can last up to three years when stored properly. On the lower end, such as sprays made with essential oils, effectiveness tops out at about a year.
The most common active ingredients in bug spray include DEET, picaridin, IR3535, and oil of lemon eucalyptus. Although these additives in bug spray are quite stable and can last a long time, it is generally recommended to dispose of insect repellent after three years. This isn't necessarily because the product expires—but rather, it loses its efficacy. "The rule of thumb is about three years, but your actual mileage may vary depending on the type of bug spray you have and how it was stored," says Wong. "If you live somewhere with heavy mosquito activity (or other biting pests), you might even consider replacing old bug spray every one or two years to ensure maximum effectiveness."
| Active Ingredient | When to Replace |
| DEET and Picaridin | After 3 years |
| IR3535 | After 2 years |
| Lemon eucalyptus or other essential oils | After 1 year |
Bug Sprays With the Longest Shelf Life
The main active ingredient in your bug spray may dictate how long it lasts. "Bug sprays containing DEET, OLE/PMD, and picaridin as their active ingredients last the longest because these chemicals are highly stable and don't break down over time," says Wong. "On average, synthetic repellents last longer in the environment than natural plant repellents because they are designed and manufactured to degrade slower."
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Bug Sprays With the Shortest Shelf Life
Bug sprays containing IR3535 tend to lose effectiveness around the two-year mark; it isn't as stable as other ingredients, like DEET. "Similarly, natural insect repellents that use essential oils may also expire relatively quickly, depending on the type of oil and the percentage used," says Wong.
In general, it's best to be cautious with oil-based repellents. "Essential oils do not spoil in the way that a food might, but they do change over time in unpredictable ways," says Nichole Powell, founder and CEO of Kinfield, which creates all-natural products for the outdoors, including repellent.
How to Know If Bug Spray Has Expired
There may be a few telltale signs that your bug spray has expired. "In certain types of bug sprays, a change in smell, color, or consistency might be an indication that it has expired or lost effectiveness," says Wong. "In other types, there might not be any noticeable changes. One way to tell is to try it on yourself, and if you're still getting a lot of bites, then it might be because your bug spray has expired."
No matter the type of bug spray you have, checking with the manufacturer to ensure your product is still effective may be helpful.
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