Does Drinking Green Beer Turn Your Pee Green?

The Truth About Whether Drinking Green Beer Turns Pee Green

Green beer is a (somewhat nasty) St. Patrick's Day tradition. Did you ever wonder whether it will turn your urine green? Science has the answer!
Green beer is a (somewhat nasty) St. Patrick's Day tradition. Did you ever wonder whether it will turn your urine green? Science has the answer!. Alex Hayden, Getty Images

Drinking green beer is a popular St. Patrick's Day activity. You may wonder whether it will turn your pee green. As a scientist, my advice is to gather data and draw your own conclusions. But, if you don't drink alcohol or are smart enough to drink good beer rather than the green stuff, here's the answer:

Green Beer Sometimes Turns Urine Green

There are two factors that affect whether the green stuff will color your pee: (1) how much you drink and (2) the dye used to turn the beer green.

Obviously, not everything green you eat or drink colors your urine. When's the last time a green salad affected your pee? Yet, green-colored Creme de Menthe and colored green milkshakes and snow cones may tint your urine and feces. Some dyes will pass through your body unchanged, filtered by your kidneys and excreted in urine in their original green form. For example, if you eat enough asparagus, it can turn your pee green and change its odor. Other pigments (e.g., chlorophyll) are metabolized by the body and broken into colorless or other-colored molecules.

Even if a pigment remains intact through your digestive system, you may not notice its effect if it's diluted by other fluid. The more green beer you drink and the more deeply-colored the beer is, the more likely you are to see the effect.

Which pigments add the Irish tint? Most green food coloring works. Also, the drugs amitriptyline, propofol, and indomethacin, as well as the B vitamins can color urine green. If you eat enough black licorice, you'll also get green pee.