Nifty·Posted on Aug 14, 2015Here's How Long Your Morning Coffee Is Actually Good ForLearn about old coffee in all its forms—this is a safe space.by Leslie StephensBuzzFeed ContributorFacebookPinterestTwitterMailLink It happens every afternoon: Around 4 o'clock, I start to fade and begin considering my half-consumed coffee at my desk. Leslie Stephens/Food52 / Via food52.com My coffee, circa 3 P.M. this afternoon. And every day, I wonder, "Can I drink that? Leslie Stephens/Food52 / Via food52.com At what point does the potential risk outweigh the promise of caffeine? So I turned to Google to find an (unofficial, but workable) answer to all my late-in-the-day-coffee questions. What if the coffee has milk in it? James Ransom/Food52 / Via food52.com When properly stored and refrigerated, milk can last for up to a week past its expiration date, but milk should not be left at room temperature for more than two hours. Those cookies, on the other hand... Is the flavor of the coffee affected? James Ransom/Food52 / Via food52.com Just as coffee beans go rancid after about two weeks, brewed coffee can start to taste bad after about 30 minutes, or the time it takes for the coffee to cool. Then you have about a 4-hour window before the oils in the coffee start to go bad, which further alters the taste. Will microwaving the coffee kill bacteria? Nicole Franzen/Food52 / Via food52.com While microwaves can kill pockets of bacteria, because they heat from the outside in, they often leave pockets of cold in the middle of food and drinks where bacteria can thrive. Does the water in the coffee spoil? James Ransom/Food52 / Via food52.com Unless water has something living in it, like flowers, it's difficult for bacteria to survive in it. Drink up. So, is coffee safe to drink after several hours? James Ransom/Food52 / Via food52.com Black coffee should be safe to drink, though it probably won't taste all that good. If it has milk in it, make a fresh pot instead—but if you're determined to still drink it (as I often am), make sure to microwave it all the way through, for an extra-classy, extra-safe 4 PM pick-me-up. Bottoms up! Tap to play GIF Tap to play GIF Asmik Ace Entertainment Catherine O'Donnell contributed to this post. For more, visit Food52.