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Unusual Findings

Blood in poop: common causes and when it is urgent

What causes blood in poop and when should I worry?

Seeing blood can be scary. Blood in poop can come from common causes like hemorrhoids or a small tear (fissure), but it can also come from infection, inflammation, ulcers, or other conditions that need medical evaluation. Use the Safety notes box as your red-flag checklist, and if you feel unsure, seek medical care.

Key takeaways

  • Bright red blood is often from a lower source (like hemorrhoids), but amount and symptoms matter.
  • Black, tarry, sticky stool can suggest upper-GI bleeding and needs urgent care.
  • Persistence matters: repeated bleeding is worth medical evaluation even if you feel okay.
  • A short log (Bristol type, color, timing, symptoms, recent meds) makes appointments and tests more interpretable.

Safety notes

  • Seek urgent medical care for large amounts of blood, clots, bleeding that does not stop, black/tarry stool, faintness, severe pain, high fever, or signs of dehydration.
  • If you are on blood thinners, pregnant, immunocompromised, or you have heart/kidney disease, escalate sooner.

What to track

  • What it looks like: bright red blood vs dark/maroon vs black/tarry
  • Where you see it: on paper, on the surface, mixed in, dripping into the bowl
  • Bristol type + frequency + timing
  • Symptoms: pain, fever, dizziness/weakness, vomiting, urgency
  • Recent triggers: constipation/straining, diarrhea, travel/food poisoning risk
  • Meds/supplements: NSAIDs, iron, bismuth (Pepto), antibiotics, blood thinners

How StoolSense helps

You want a calm way to label what you see and decide whether to watch, track, or seek care.

You want consistent notes you can share with a clinician without over-documenting.

You wipe and see red. Your brain jumps straight to worst-case scenarios.

This page is a calmer triage: what “counts” (and what doesn’t), what makes it urgent, and what to write down so you’re not trying to remember details under stress.

First: blood vs red-tinted stool

Red stool can be food-related (beets, dyes). Blood looks different.

A practical distinction:

  • Red-tinted stool: the stool itself is colored.
  • Blood: streaks, drops, clots, or blood mixed in.

If you can’t tell, or you feel unwell, seek medical advice.

Common causes (plain English)

These are not diagnoses, just the most common buckets clinicians think about.

1) Hemorrhoids or fissures (local irritation)

Often shows up as:

  • Bright red blood on paper or on the surface
  • Bleeding after straining
  • Pain with wiping (often more fissure-like)

2) Diarrhea, irritation, or infection

Diarrhea can irritate tissue and some infections can cause bloody diarrhea.

Escalate sooner if you have fever, dehydration, severe pain, or symptoms that keep worsening.

3) Inflammation

Inflammatory conditions can cause bleeding, mucus, urgency, and persistent symptoms.

This is one reason clinicians may order inflammation markers or other tests.

Some medicines can increase bleeding risk or irritate the GI tract.

If you take blood thinners or frequent NSAIDs, mention it.

What would count as a signal to book an appointment?

If you’re not in a red-flag situation, these are reasonable “this deserves follow-up” signals:

  • Bleeding repeats across multiple bowel movements or keeps showing up over several days
  • You see blood mixed into stool (not just on paper) or you also have mucus, urgency, or persistent diarrhea
  • The pattern is new for you and doesn’t settle once constipation/straining improves
  • You’re on NSAIDs, blood thinners, or you have other risk factors (escalate sooner)

What to track (minimal, 7-day version)

If you’re not in a red-flag situation, track just enough context to stop guessing:

  • What it looks like (bright red vs dark/maroon vs black/tarry)
  • Where you see it (paper vs mixed in)
  • Bristol type + frequency
  • Any diarrhea or constipation/straining
  • Symptoms (pain, fever, dizziness)
  • Recent meds (NSAIDs, antibiotics, blood thinners) and supplements (iron/Pepto)

When stool tests may come up

Stool tests are usually ordered to answer a specific question (infection vs inflammation vs bleeding).

If you want a map of the common categories, see: Types of stool tests.

FAQs

Is bright red blood in stool always serious? +
Not always. Bright red blood is often from a lower source (like hemorrhoids or a fissure). But amount, persistence, and symptoms matter. Large amounts, clots, or feeling unwell should be evaluated urgently.
What does black, tarry stool mean? +
Black, tarry, sticky stool can be a sign of upper-GI bleeding (melena) and needs urgent medical evaluation, especially with weakness, dizziness, faintness, or shortness of breath.
Can constipation cause blood in stool? +
Constipation and straining can cause hemorrhoids or small tears (fissures), which may bleed. If bleeding repeats, worsens, or you have significant pain, seek medical advice.
Can diarrhea or infection cause blood in stool? +
Yes. Some infections and inflammatory conditions can cause bloody diarrhea. If you have fever, severe pain, dehydration, or persistent symptoms, seek medical care.
When should I stop tracking and go to urgent care? +
Go urgently if there is a lot of blood, clots, black/tarry stool, severe or worsening pain, faintness, weakness, high fever, confusion, or signs of dehydration.
What should I tell a clinician? +
Share when it started, what it looks like (bright red vs dark vs black/tarry), how much and how often, Bristol type and frequency, symptoms (pain, fever, dizziness), and meds (NSAIDs, antibiotics, blood thinners, iron/Pepto).

References

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