Often we open a bottle of wine only to pour one glass and leave the remainder in the fridge. But how long do you have before that half full bottle actually goes off? You should really be drinking a bottle of wine within four to six hours of opening it, as it won’t taste very nice after 24 hours. When you’ve opened the wine, there’s now a gap of air that’s filling the bottle. Over time, when the wine is exposed to too much air, the phenols will dissipate and become negative flavours.