Does insect repellent expire?

Insect repellent is used to deter bugs and pests from biting or approaching you. Various types of bug sprays and repellents can be used to minimise your exposure to annoyances such as mosquitoes and flies when outdoors during warm months when these pests thrive. Because different products are used to create insect repellents, the shelf lives of these items can vary.

Insect repellent is legally considered to be a form of pesticide. The National Pesticide Information Center classifies any product that can be used to kill or repel pests, such as insects, as a pesticide. Pesticides designed as insect repellent can contain both natural and chemical ingredients. According to the Center for Disease Control and Prevention, the most common modern repellent ingredients include DEET, Picaridin, Oil of Lemon Eucalyptus and a chemical that is known simply as IR3535. Common ingredients in recipes for homemade bug sprays and repellents include white vinegar, lemon peels, and citronella or eucalyptus oil. Avon Skin So Soft is also often used as an insect repellent.

The ingredients in insect repellent can separate, settle, lose effectiveness and generally degrade over time and exposure to changing temperatures and environments. These changes rarely improve the product and instead can cause it to break down until it offers little to no defence against bugs. Extremely old repellent might cause skin irritation or rashes.

Insect repellents have instructions on their bottles that typically call for storage in moderate temperatures and out of direct sunlight. Failure to store products properly can cause ingredients to lose their effectiveness more quickly than they would otherwise.

Most insect repellents have an expiration date stamped somewhere on the bottle or container, though the FDA does not require an expiration date on those that have a shelf life of more than 36 months. The expiration date is there to protect the safety of the user and guarantee the efficiency and effectiveness of the product. An insect repellent that is past its expiration date is no longer guaranteed effective or even safe by its manufacturer and should not be used.

DEET is a chemical compound commonly used in insect repellents. DEET is considered very stable and can last a long time, and not all pesticides that contain DEET will have an expiration date. As a general rule, however, replace any insect repellent that has been in your home for two years or longer with a new product to ensure effectiveness, Jim Baral of New York's Mount Sinai School of Medicine tells Fitness Magazine.