Picaridin lasts for at least 3 years, in my experience. After that a lotion may become kind of soapy and non-homogeneous. An article referenced on Sawyer's website says that Picaridin doesn't have expiration date, but gets less effective over time, same as DEET. On Amazon Q&A a message signed by Sawyer Products says: Our insect repellents and sunscreens have a shelf life of 10+ years when properly stored in a cool/dry location away from direct UV exposure.
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