Seeing blood in your child’s stool is alarming — but many causes are treatable and not dangerous. The key is figuring out:

  • How much blood
  • What it looks like
  • Your child’s age
  • Whether there are red flags

This guide covers the most common causes by age and what to do next.

Important: This is educational guidance. If your child looks unwell or you are unsure, seek medical assessment.

Step 1: Red flags (go to Emergency now)

Seek urgent care now if any of the following apply:

  • Large amount of blood, clots, or continuous bleeding
  • Black, tarry stool (possible upper GI bleeding)
  • Pale, weak, dizzy, fainting, very sleepy
  • Severe abdominal pain, belly swelling, or persistent vomiting
  • Fever with very unwell appearance
  • Bloody diarrhea with dehydration
  • Baby < 3 months with significant bleeding or poor feeding
  • Suspected swallowed foreign body, caustic ingestion, or trauma

Step 2: What does the blood look like?

Bright red blood on the toilet paper / outside of stool

Often from:

  • Anal fissure (small tear)
  • Hemorrhoids (less common in kids but possible)

Bright red blood mixed in stool or dripping into toilet

Can be from:

  • Infectious colitis
  • Polyps (usually painless bleeding)
  • Inflammatory bowel disease

Dark red / maroon stool

Possible lower intestinal bleeding (more significant) — assess urgently if large amount.

Black, tarry stool (melena)

Possible bleeding higher up (stomach/upper small intestine) — needs urgent assessment.

Step 3: Causes by age

Newborns (0–28 days)

Common possibilities:

  • Swallowed maternal blood (from delivery or cracked nipples)
  • Anal fissure (less common but possible)
  • Milk protein allergy (can cause small streaks of blood/mucus)

More serious possibilities (needs urgent assessment):

  • Infection
  • Intestinal problems (especially if unwell, vomiting, distended belly)

Infants (1–12 months)

Common:

  • Anal fissure from constipation / hard stools
  • Milk protein allergy (blood + mucus, irritability; may have eczema)

Important:

  • Infectious colitis (diarrhea, fever)
  • Intussusception (episodes of pain, pallor; sometimes blood/mucus stools)

Toddlers and preschool (1–4 years)

Common:

  • Constipation → fissure (most common)
  • Infectious diarrhea (blood + diarrhea, fever)

Important:

  • Polyps (often painless bleeding)
  • Intussusception (episodic pain)
  • Rare: Meckel’s diverticulum (can cause painless significant bleeding)

School age (5–12 years)

Common:

  • Constipation with fissure
  • Infectious colitis

Important:

  • Polyps
  • Inflammatory bowel disease (IBD) — consider if:
    • weight loss or poor growth
    • chronic diarrhea
    • nocturnal stooling
    • anemia, fatigue
    • family history of IBD
  • Celiac disease can cause symptoms, but blood is not typical unless another issue co-exists.

Teens (13+ years)

Common:

  • Constipation with fissure
  • Infectious colitis

Important:

  • IBD
  • Hemorrhoids (especially with constipation/straining)
  • In sexually active adolescents: proctitis or infections may be relevant and should be assessed respectfully and privately.

Step 4: The most common cause overall: anal fissure (tiny tear)

Clues:

  • Bright red blood on the surface of stool or toilet paper
  • Pain or crying with stooling
  • Hard, large stools
  • Fear of stooling / withholding

What helps:

  • Water and fiber
  • Gentle stool softening plan guided by your clinician
  • Regular toileting routine with feet supported

If bleeding keeps happening, the constipation plan often needs to be stronger and longer than expected.

Step 5: What information helps your doctor

If you can, note:

  • Age of child
  • Amount of blood (a few streaks vs spoonfuls)
  • Color (bright red vs dark vs black)
  • Stool pattern (hard? diarrhea? normal?)
  • Pain with stooling?
  • Fever, vomiting, abdominal pain?
  • Recent travel, sick contacts, new foods
  • Medications (especially antibiotics, ibuprofen, iron)

A photo can help — awkward but useful for accurate assessment.

Step 6: When to book a clinic appointment (not emergency)

Book an appointment soon if:

  • Small bleeding episodes repeat (even if child seems well)
  • Chronic constipation is present
  • Blood mixed with stool (not just on paper)
  • Any growth concerns, weight loss, chronic diarrhea, or fatigue

Quick summary

  • Many cases are from constipation and fissures.
  • Large bleeding, black stool, severe pain, dehydration, or an unwell child needs urgent assessment.
  • Recurrent bleeding deserves a structured evaluation to rule out polyps, infection, and IBD.

Next, if you want, I can write: “My child can’t swallow after hard food once: what to do and when it’s an emergency.”

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