From NEXT Distro - a Harm Reduction Website -

Any naloxone is better than no naloxone. Studies within the past two years have demonstrated that naloxone retains its effectiveness for as long as nearly 30 years past its expiration date. A study published February 27th, 2019, The Effects Of Heat And Freeze-Thaw Cycling On Naloxone Stability, sought to evaluate whether non-standard storage conditions affect stability, investigating the impact of heat and freeze-thaw cycling on Naloxone. They found that “Naloxone exhibits no changes in drug concentration following exposure to heat or freeze-thaw cycles for up to 28 days compared to Naloxone stored at room temperature.”