Unopened vials of Humulin R should be stored in a refrigerator between 36°F to 46°F (2°C to 8°C). It's important not to freeze them, and if they have been frozen, they should not be used. Additionally, unopened vials should not be used after the expiration date indicated on the label.
Opened (in-use) vials of Humulin R can be stored either in the refrigerator or at room temperature below 86°F (30°C). It's crucial to keep them away from heat and direct sunlight. Once opened, the vial should be used within 31 days, and any remaining insulin should be discarded after this period, even if there is some insulin left in the vial. Just like unopened vials, opened vials should not be used past the expiration date stated on the label.