The reason wine goes bad is because when opened powerful chemical changes start to occur in the wine.
Oxygen rushes in and sulfur dioxide, which is added to nearly all wines as a preservative, dissolves into the air.
Once opened the wine goes bad within 5 days.
Unopened wine is usually able to last forever basically but it loses it's taste the longer it is left unconsumed.
Most ready-to-drink wines are at their best quality within 3 to 5 years of production, although they will stay safe indefinitely if properly stored; fine wines can retain their quality for many decades.
The best way to enjoy your wine fresh is to drink it shortly after you purchase it.
However, you can still enjoy unopened wine about 1–5 years after the expiration date, while leftover wine can be enjoyed 1–5 days after it has been opened, depending on the type of wine.
You can drink old opened wine although it won't taste very good.
The old opened wine won't make you sick but it will taste terrible and it's best to avoid drinking the old opened wine.
Opened wine does eventually go bad.
Once open the opened bottle of wine will last for about 5 days before it goes bad and tastes bad.
After opening wine the wine lasts for about 5 days.
Most wines last open for only about 3–5 days before they start to go bad.
Of course, this greatly depends on the type of wine!
Don't worry though, “spoiled” wine is essentially just vinegar, so it's not going to harm you.
In general, wine lasts one to five days after being opened.
It's true, the primary reason wines go bad is oxidation.
Too much exposure to oxygen essentially turns wine into vinegar over time.
So if you don't plan to finish a bottle, cork it and stick it in the fridge to help preserve it.
Drinking an already-opened bottle of wine will not make you sick.
Pouring yourself a glass from a bottle that's been open for longer than a week may leave you with an unpleasant taste in your mouth.
To give open wine bottles a longer life you should put both red and white wines in the fridge.
And just as with beer, it's perfectly fine to move your vino out of the fridge for a bit and put it back once you have more room, as long as you don't do it with the same bottle too many times.
Temperature extremes are what destroy a wine, and for that matter beer, too, not moving it in and out of a fridge.
Signs that your wine has gone off or has gone bad are.
The smell is off.
The red wine tastes sweet.
The cork is pushed out slightly from the bottle.
The wine is a brownish color.
You detect astringent or chemically flavors.
It tastes fizzy, but it's not a sparkling wine.