In the split-second before you flush, you realize something’s different. Your poop looks a little green. Or sticky and black. Should you worry?

Some bowel movement changes can be traced directly to diet. Green streaks? Last night’s spinach salad. A red hue? Any chance you’ve eaten cherry Jell-O lately? But shifts in stool color, texture, frequency and other features sometimes signal a health problem that needs attention. Some common poop clues, decoded:

CLUE: Black or tarry. Iron supplements, antacids, bismuth-based anti-diarrhea drugs, blueberries, black licorice and binging on chocolate wafer cookies can all make BMs look black, according to the American Academy of Pediatrics. So can blood from the upper gastrointestinal system — the esophagus, stomach or first part of the small intestine. When bleeding’s to blame, black-tinged stool may also look sticky or tarry and have a foul odor. Call your doctor immediately. You may need emergency help if you faint, are sweating or have a rapid heart rate.

CLUE: Bright red or maroon, reddish spots or streaks. If you’re seeing red in the bowl, possible food sources are tomatoes, beets, cranberries, red peppers and red-tinted Jell-O, frosting , cereal and other kid foods. Rectal bleeding from hemorrhoids or anal fissures (splits in the skin of the anus) can cause bright red BMs. So can more serious medical conditions including colitis, inflammatory bowel disease, polyps and colon cancer, so it’s important to see your doctor. Get emergency help if you pass a large amount of blood or have any of the symptoms listed above.

CLUE: Green. Most often, bile is to blame for green bowel movements. This digestive fluid is dark green when it leaves the gallbladder. It normally turns brown as it passes through the digestive system, giving poop its characteristic hue. But if the intestines are moving material quickly — due to diarrhea, for example — bile stays green. Green leafy vegetables and green Jell-O can also tint stool green.

CLUE: Pale or yellow. Pale poop may be a sign of celiac disease, a disorder in which the immune system attacks the lining of the intestine when the grain protein gluten is present. Chronic inflammation of the pancreas or a blocked pancreatic duct may be to blame for bowel movements that look yellow and greasy. See your doctor promptly for any of these stool cues.

CLUE: Clay colored. Conditions that reduce the production or flow of bile, such as a liver infection, a blocked bile duct or gallstones, can cause poop to take on a clayish cast, according to the National Institutes of Health. Contact your doctor.

CLUE: Dry, hard, infrequent. You also may feel like you haven’t completely emptied your bowels. These are all signs of constipation, which can be caused by any one of a number of things: a low fiber diet, not drinking enough water, medications such as narcotics, antacids and even some diuretics and antidepressants, too little exercise, holding back when you need to make a bathroom trip or a medical condition, according to the National Institutes of Health. Pregnancy and travel can cause constipation as well. The American Gastroenterological Association recommends gradually increasing the fiber in your diet (sip more water, too). If these do-it-yourself steps don’t help, see your doctor.

CLUE: Loose and watery. If you have three or more bowel movements in a day, it’s probably diarrhea, which can be caused by a virus, bacterium or parasite. (Diarrhea is a particular risk for travelers in less-developed areas of the world.) In that case, it can help to drink oral rehydration beverages and steer clear of dairy products. Get medical help if the diarrhea doesn’t clear up after 48 hours. Loose and frequent stools that persist for more than four weeks may be due to celiac disease, pancreatitis, lactose intolerance (reduced ability to digest sugars in milk) or irritable bowel syndrome (which can also cause constipation), according to the American College of Gastroenterology.  

Sari Harrar is an award-winning health, medicine and science journalist whose work appears in Dr. Oz The Good Life magazine, Good Housekeeping, O--Oprah Magazine, Organic Gardening and other publications.