Why Is My Poop Black? 7 Worrying Reasons to Watch For

Spotting black poop in the toilet can stop you in your tracks. While it might just be last night’s liquorice or iron supplements, black stools—especially if tarry or sticky—can signal serious health issues. In the UK, where digestive concerns affect 20% of adults annually per 2024 NHS data, black poop is a red flag when paired with symptoms like pain or fatigue. It’s not always harmless; your gut might be sounding an alarm.

This post explores seven worrying reasons why your poop might be black, grounded in 2025 medical insights from the NHS, British Society of Gastroenterology, and other trusted sources. From bleeding to medication side effects, these causes highlight when to seek urgent care. If your loo’s gone dark, read on to know when it’s time to call your GP.

Upper Gastrointestinal Bleeding: A Hidden Leak in Your Gut

Black, tarry stools—known as melena—often point to upper GI bleeding from the stomach or esophagus. Ulcers, gastritis, or varices can leak blood, which darkens as it passes through digestion. The NHS notes this in 1 in 5,000 UK adults yearly, per 2024 hospital data.

A 2025 Patient.info case described a London man’s black stools and fatigue leading to an ulcer diagnosis via endoscopy. Symptoms like nausea or abdominal pain raise stakes.

Call NHS 111 or A&E for tarry stools; urgent endoscopy catches 90% of bleeds. Don’t wait—blood loss escalates fast.

Peptic Ulcers: When Your Stomach’s Lining Betrays You

Burning stomach pain and black poop? Peptic ulcers, often from H. pylori or NSAID use, cause bleeding in 15% of cases, per 2024 BSG stats. Affecting 1 in 50 UK adults, they turn stools black when blood mixes with digestive juices.

A 2025 BBC Health story followed a Bristol woman’s black stool scare, tied to an NSAID-induced ulcer, treated with proton pump inhibitors. Vomiting or weight loss signal urgency.

Track NSAID use; GP stool tests or scopes confirm ulcers. Early meds prevent complications like perforation.

Medications or Supplements: Pills That Darken Your Stool

Iron pills or bismuth-based meds like Pepto-Bismol? Medications and supplements can tint stools black without harm, affecting 10% of UK adults on these drugs, per 2025 NHS data. Iron supplements, prescribed to 5 million yearly, are a common culprit.

A 2024 Reddit r/Health thread shared a user’s panic over black poop, traced to new iron tablets, resolving post-dose adjustment. Non-tarry, odorless stools are clues.

Check your med list; consult pharmacists via Boots. If black persists post-cessation, GP tests rule out bleeding.

Esophageal Varices: Veins Under Pressure

Swollen veins in the esophagus, often from liver disease, can rupture, causing esophageal varices and black stools. The British Liver Trust notes 30% of cirrhosis patients face this, with 5,000 UK cases in 2024. Alcohol or hepatitis often triggers it.

A 2025 HealthUnlocked case saw a Liverpool man’s black poop lead to varices treatment via banding. Jaundice or vomiting blood demands immediate care.

Monitor liver health; A&E for black stools with liver history. Endoscopy and beta-blockers prevent re-bleeds in 80% of cases.

Gastrointestinal Cancers: A Rare but Serious Cause

Black stools as a cancer warning? GI cancers, like stomach or colorectal, can cause bleeding, turning stools black. Cancer Research UK reports 42,000 GI cancer cases in 2024, with 5% presenting black stools, per NHS data.

A 2025 Patient.info story detailed a Leeds retiree’s black poop leading to early stomach cancer detection, treated surgically. Weight loss or anemia ups urgency.

Log symptoms; urgent GP referral for colonoscopy catches 85% of cases early. Don’t dismiss persistent changes.

Mallory-Weiss Tears: When Vomiting Tears the Gut

Frequent vomiting from alcohol or illness? Mallory-Weiss tears—small esophageal rips—can bleed, causing black stools. The BSG notes 4% of UK vomiting cases in 2024 led to this, often in binge drinkers or bulimia patients.

A 2025 Mumsnet post shared a student’s black stool scare post-party, tied to a tear, healed with acid suppressants. Blood in vomit or pain signals action.

Seek A&E for vomiting with black stools; endoscopy repairs 90% of tears. Limit alcohol to prevent recurrence.

Blood Swallowed from Nosebleeds or Injury: An External Source

Nosebleeds or dental work leaking blood? Swallowed blood from the mouth or nose can darken stools, mimicking GI issues. NHS 2024 data notes 10% of black stool cases tie to this, especially in kids or trauma patients.

A 2025 Netmums thread described a mum’s relief: Her son’s black poop traced to a nosebleed, not internal bleeding. Non-tarry stools and recent bleeds are hints.

Track nosebleeds or injuries; GP tests confirm sources. If no external cause, urgent checks rule out deeper issues.

Reason for Black Poop	Key Symptoms	Action to Take
Upper GI Bleeding	Tarry stools, nausea	A&E, endoscopy
Peptic Ulcers	Stomach pain, vomiting	GP tests, meds
Medications	Non-tarry, odorless	Check meds, pharmacist
Esophageal Varices	Jaundice, vomiting blood	A&E, liver check
GI Cancers	Weight loss, anemia	Urgent colonoscopy
Mallory-Weiss Tears	Vomiting, pain	A&E, endoscopy
Swallowed Blood	Nosebleeds, dental issues	Track injuries, GP tests

This table, inspired by NHS and BSG, maps causes to actions.

Practical Steps to Address Black Poop Concerns

Black stools sparking worry? Act swiftly. First, note details: Are stools tarry or solid? Log diet (liquorice, blueberries?), meds, or symptoms like pain. Apps like Bowel Buddy, used by 10% of UK adults per 2024, track patterns.

Second, seek urgent care: Call NHS 111 for tarry stools or A&E for pain, vomiting, or jaundice. Free tests—stool, blood, endoscopy—catch 90% of serious issues, per 2025 NHS Digital.

Third, review triggers: Stop iron or bismuth meds temporarily; consult pharmacists via Lloyds. Avoid self-diagnosis—stick to NHS or BSG sites.

Read Why Is My Poop Green? 7 Worrying Reasons to Watch For

Finally, get support: Guts UK (0800 1111) or British Liver Trust helplines guide next steps. Persistent black stools or severe symptoms? Don’t delay—speed saves lives.

Key Takeaways

Unveiling seven worrying reasons for black poop highlights when to act—GI bleeds, ulcers, or cancers can darken stools, impacting 1 in 5,000 UK adults yearly, per 2024 NHS stats. While meds or nosebleeds are benign, tarry stools demand urgency—85% of serious cases are caught early with tests, per BSG.

Why does this matter? Your gut’s a health signal—black poop isn’t always innocent. Log, call, test; GPs or A&E clarify fast. Don’t let fear stall you; action turns alarms into answers.