Elk in Rocky Mountain National Park
 

When is my DEET product too old to use?

DEET is very stable and is effective indefinitely as a repellent. For this reason, the federal government doesn't require an expiration date on product labels. But manufacturers of repellents say that the feel, smell and appearance of their products may change after about three years. This does not reduce the DEET's ability to repel mosquitoes and ticks but may make the product less appealing to users. If you're not sure about your particular product, contact the manufacturer.

Background Image: Rocky Mountain National Park by Sue Burke. All rights reserved.