Can Coffee Cause Bloody or Black Stools?

You should not expect to see blood in your stool after drinking coffee. While coffee can stimulate your digestive system and speed up bowel movements, it shouldn't cause gastrointestinal bleeding.

A variety of gastrointestinal issues can cause blood in your stool. Plus, some foods can make your stools red in color, meaning they look bloody but don't actually contain blood. It's best to consult your doctor if you notice dark or bright blood in your stool.

‌Read more: ‌9 Ways You're Doing Coffee All Wrong — and How to Get It Right

Many of the effects of coffee on the body are related to the beverage's caffeine content. According to the Food and Drug Administration (FDA), an 8-ounce cup of coffee contains around 80 to 100 milligrams of caffeine. Caffeine content varies depending on what coffee beans were used and how strong the coffee was brewed. The FDA recommends that adults limit themselves to around 400 milligrams of coffee per day.

As the Cleveland Clinic explains, caffeine works by stimulating your central nervous system. You can feel the effects of caffeine as soon as 15 minutes after consuming it, and the substance has a half-life of roughly six hours. The clinic says it can take up to 10 hours for caffeine to pass through your body entirely.

While many people rely on caffeine daily, consuming too much of it can be harmful. Potential side effects of consuming too much caffeine include:

• Dehydration
• Increased blood pressure
• Headaches
• Feeling dizzy
• Feeling jittery
• Insomnia
• An increased heart rate

Caffeine is also considered an addictive substance, and some people who consume a lot of caffeine may experience caffeine withdrawal when they try to cut down or stop. Symptoms of caffeine withdrawal can include flu-like symptoms, irritability and trouble concentrating.

Harvard Health explains that caffeine can speed up your digestive system, contributing to diarrhea or loose, dark stools. However, if you notice blood in your stool after drinking coffee, a health condition may be the cause.

According to the Mayo Clinic, gastrointestinal bleeding can lead to blood in your stool or vomit. Common causes of upper gastrointestinal bleeding include peptic ulcers, inflammation of the esophagus linked to acid reflux, tears in your esophagus and a condition called esophageal varices which causes enlarged veins in the esophagus.

Lower gastrointestinal bleeding can be caused by hemorrhoids, anal fissures, inflammatory bowel disease, diverticular disease, tumors and polyps in the colon. Physicians can use imaging technology to locate the source of the gastrointestinal bleed, then decide how to treat it.

The presence of blood in your stools can contribute to a black or tarry appearance, depending on where the blood is coming from. Rush University Medical Center says that black or dark blood in stool typically signifies an upper gastrointestinal bleed, and that bright red blood in a stool tends to come from bleeding lower in the gastrointestinal tract.

If you pass bowel movements with the appearance of ground coffee, blood in your stool is a potential culprit. If you notice you're passing black stools, treatment options depend on what is causing them.

The presence of blood may make your stool appear red, but another potential culprit is your diet. According to UC San Diego Health, food and drinks that contain red food coloring can make your bowel movements red, and so can eating large quantities of red-colored fruits and vegetables like beetroot and cranberries. Similarly, orange foods like carrots can contribute to orange-red stools.

Another potential cause: hemorrhoids. Hemorrhoids are swollen veins in your rectum and anus that can bleed during bowel movements, leading to fresh blood in the toilet bowl or when you wipe after using the bathroom. In the case of hemorrhoids, blood in your stool is not a sign of internal bleeding in your gastrointestinal tract.

If you have vomit that looks like coffee grounds, the Mayo Clinic says that's likely a sign of coagulated blood in your vomit and recommends seeking immediate medical attention. That's because vomiting blood can be a symptom of potentially serious conditions, including:

• Liver failure
• Cirrhosis, a scarring of the liver
• Various types of cancer, including stomach cancer, pancreatic cancer and esophageal cancer
• Peptic ulcers
• Tearing or inflammation in the gastrointestinal tract

The clinic also says to watch for any symptoms of shock or severe blood loss related to vomiting blood, including fainting, nausea, confusion, blurred vision, dizziness, shallow breathing, low urine output and clammy, cold skin.

The bottom line is that there shouldn't be blood in your stool after drinking coffee. If you're worried about bloody or black stools, treatment options are available depending on what is going on. Consult your doctor about symptoms that concern you.

If you're worried that you're drinking too much caffeine, consider cutting down on the amount of coffee, tea and caffeinated sodas you drink each day. Immediately stopping all caffeine consumption may lead to caffeine withdrawal, which makes gradually decreasing your intake the better bet.

One option is to slowly dilute your caffeinated beverages each day, eventually phasing them out entirely. You can also try mixing caffeinated coffee with decaf, increasing the ratio of decaf to caffeinated until the drinks are completely decaffeinated.

It's important to note that decaf coffee still contains caffeine — but a much lower amount. Any coffee marked as "decaf" must have at least 97 percent of the caffeine removed, according to the FDA. That means an 8-ounce cup of decaf coffee could contain between 2 to 15 milligrams of caffeine.