Storing and Handling Insulin Correctly

Insulin is a protein, and like most proteins it's sensitive to heat, freezing, and direct sunlight. Unopened insulin belongs in the refrigerator, ideally between 2–8°C, until its expiry date. Never let it freeze — frozen insulin loses effectiveness permanently, even after it thaws.

Once a pen or vial is in use, most insulin can be kept at room temperature (below 25–30°C, check your specific product's leaflet) for a limited number of days — commonly around 28 days, though this varies by brand. Mark the date you opened it so you don't lose track.

Before every injection, look at the insulin itself. Rapid- and long-acting clear insulins should stay clear — cloudiness, clumps, or discoloration mean it should be discarded. Cloudy insulins (like NPH) should look evenly milky after gentle rolling, not clumped or crystallized.

Traveling or living somewhere hot? Insulated cooling cases and cold packs (that don't directly touch the insulin) help keep it in range without freezing it. Never leave insulin in a car, near a window, or in checked airline luggage where cargo holds can freeze.

When in doubt, don't use it. A pen or vial that's been mishandled might still look normal but work poorly, leading to unexpectedly high blood sugar. It's a small cost to replace compared to the risk of relying on insulin that's lost its potency.