Used for indigestion, nausea, or diarrhea, this pink medication can make your tongue and stool turn charcoal black. This temporary and harmless effect occurs when bismuth (the active ingredient) interacts with hydrogen sulfide in your mouth and colon (large intestine). Brushing your teeth and tongue or rinsing your mouth right after taking each dose reduces the black-tongue effect. But depending on the time it takes for food to move through your colon, your stool can remain dark for several days after you stop the drug.
Eating beets can lend a brilliant crimson hue not just to your plate but also to your urine, thanks to the pigment betalain in this root vegetable. How red urine becomes may depend on such factors as your blood iron level and acids in food, such as ascorbic acid (vitamin C) or oxalic acid (as in spinach, Swiss chard, and many other foods). Genes may additionally play a role in "beeturia." There are also reports of beets turning stool reddish.
If your stools have taken on a ghostly gray or pale color, that bowl of New England clam chowder you ate the other day may be to blame, according to many anecdotal reports online. Animal studies suggest that the color change may be due to titanium dioxide, which is added to some canned chowders (and many other foods) to make them look white, rather than gray. Food labels may list titanium dioxide, but more often they just say “artificial color.” Titanium dioxide in food is controversial due to unresolved safety concerns.
Medications that can turn urine green include the antacid cimetidine (Tagamet), the anesthetic propofol (Diprivan), and the nonsteroidal anti-inflammatory drug indomethacin (Indocin). It may look alarming, but it’s harmless. Methylene blue, used in some diagnostic tests and to treat rare conditions such as methemoglobinemia (an inability of red blood cells to carry oxygen), can turn your urine blue—or, more typically, green, when the blue pigments in methylene blue combine with a compound that gives urine its normal yellow color.
Asparagus is notorious for making urine smell somewhat like rotten or boiled cabbage. It has long been debated whether only some people are capable of producing the odor, or whether all people make it but only some can smell it. A 2011 study confirmed that people differ both in their ability to produce the odor and in their ability to perceive it, due to genetic variations. A 2010 study in PLOS Genetics similarly found a genetic difference between people who can detect the odor and those who cannot.
There are numerous online comments from people who brushed with certain toothpastes and later noticed “stringy stuff” collecting along their gums. This tissue sloughing can occur if you are sensitive to some toothpaste ingredients—notably pyrophosphates in tartar-control products such as Crest Pro Health. If you’ve noticed this effect, switch to a non-tartar-control toothpaste without the offending ingredient. Sodium lauryl sulfate, a common foaming agent in toothpastes, has also been linked with tissue sloughing in some people.
Some people get itchy, blistered skin (contact dermatitis) when they peel and cut raw butternut or acorn squash. In a case reported in Contact Dermatitis in 1994, a woman who developed this allergic skin condition was treated with a prescription topical corticosteroid. The condition quickly resolved, only to recur several weeks later when she again peeled and cut squash. Triterpene compounds are thought to trigger the hypersensitivity. If you have had this reaction from butternut or acorn squash (or other produce), wear rubber or latex gloves when preparing them.
Capecitabine is a chemo drug used to treat colon, breast, and other cancers. But it has a rare, and strange, side effect: loss of fingerprints. At first, researchers thought the fingerprints disappeared due to a blistering of the skin that can occur from the drug. But patients can develop the skin condition and not lose their fingerprints, and vice versa. It's temporary, but it can compromise identification in the meantime. Patients going abroad should carry a doctor’s note indicating that they are taking this drug, since some countries require fingerprints upon entry and departure.
If you experience color (or other) changes in your urine or stool, or have any other unusual bodily reactions such as strange rashes—and there is no obvious trigger—see your doctor to make sure it’s not something that needs evaluation and treatment. Black stool, for example, can be a warning sign of gastrointestinal bleeding. Pale poop can be due to a variety of potentially serious conditions, including a blockage in the liver’s bile duct. And green urine is sometimes not innocuous. It could, for instance, signal a urinary tract infection.