Zenegra 100 mg (sildenafil citrate) tablets generally do not lose effectiveness immediately after opening the package, assuming they are stored properly. However, here’s what you should know: Blister packs (which Zenegra usually comes in) protect each tablet individually. Opening the outer box does not affect the shelf life of the sealed tablets inside. Once a tablet is removed from its blister, it should ideally be used within a few days to avoid exposure to moisture, light, and Zenegra 100 mg can degrade the active ingredient over time. Keep in the original blister pack until ready to use. Store at room temperature (15°C to 30°C). Keep away from direct sunlight, humidity, and heat (e.g., not in a bathroom or near a stove). It has changed color (e.g., faded, yellowed, or darkened). It smells off or has visible cracks, powder, or moisture damage. It's past the expiration date printed on the pack. If stored properly and not physically damaged or exposed to air/humidity: A Zenegra tablet remains effective until its printed expiration date, even after opening the box—but use each tablet soon after popping it from the blister.