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DEET-based insect repellents, which are the most common type of repellents sold in the United States, do not have expiration dates because DEET lasts indefinitely, according to DEETOnline.org. Because repellents do not become hazardous over time, the federal government does not require manufacturers to print expiration dates on the packaging. However, some manufacturers encourage consumers to discard repellents that are more than three years old, as the product’s odor and texture may change in this time.
While DEET is the most common insect repellent in use, several alternatives exist. One of the most common DEET alternatives is picaridin. Created in the 1980s, picaridin-based products do not have expiration dates. Another common DEET alternative is IR3535, which is commonly added to lotions and skin-care products. These products have varying shelf lives, ranging from 18 to 36 months.
Safe for the Skin
While some people worry about the relative danger of DEET, the product has been thoroughly reviewed over the last 20 years by a variety of scientists, who have all found the chemical to be relatively safe. DEET does not harm the immune system of people, but it can cause health problems in rare cases when applied to the skin. Popular Science states that doctors recommend DEET-based repellents in areas where people are exposed to serious mosquito-borne diseases, such as West Nile virus or malaria.