On hiking trips, at the beach, or at summer camp, bug spray can be a life-saver. It is especially important for babies and children, or others who are sensitive to irritating stings and bites. Depending on the brand, though, last season's bug spray may not work this season. As with many other products, the efficacy of bug spray can decrease over time and may not be safe to use after it has expired. Luckily, there are several easy ways to check bug spray for expiration.
Check the Container for an Expiration Date
Examine the bug spray container. Many companies print an expiration date on the bottom or back of the bottle or can. Outer packaging such as a cardboard box may also have a printed expiration date.
If there is no expiration date, look on the container for a product code and the company phone number. The product code may be printed on the bottom of the bottle or can, but the company phone number is almost always on the back of the container under the instructions for use.
Call the company and ask them to date the bug spray using the product code.
Test the State of the Container and the Spray Odor
Holding the can away from your face, pump the nozzle to check its action. Dirt or dust can block a nozzle. The spray should come out easily and evenly. If it does not, though the bug spray itself may still be good, the state of the container may make it unsafe or hard to use.
Inspect the bug spray can or bottle for rust, dents, cracks or other signs of decay. Heat, light and water may damage the container. The state of the can often indicates the age of the product.
Spritz a little of the spray onto a piece of paper. Bug spray usually has a recognizable strong smell; if the odor seems altered or diminished, the spray is probably past its expiration. It may not be possible to test unscented bug spray this way.
Deet, a common ingredient in bug spray, does not expire. If your bug spray contains deet, check the container now and then to make sure it is in good shape, but otherwise the spray should remain usable.
Regardless of the expiration date or age of the product, if your bug spray causes a rash or other irritation, discontinue use immediately.
If the container looks old or corroded but you believe that the spray is still good, be very careful while spritzing it. If the nozzle is blocked or damaged the spray may shoot out in unexpected direction. If you get bug spray in your eyes, rinse them thoroughly with plenty of water.