Lower Back Pain And Blood In Stool: Causes Simplified (Dr. Farahat)


Lower back pain and blood in the stool can be a sign of painful anal or rectal conditions such as anal fissures, Rectal inflammation or ulcers, and Inflammatory bowel disease. Or colorectal cancer.

Always consult your doctor if you are unsure about the cause of blood in stool and back pain.

Here is a breakdown of the nine causes of bloody stools and lower back pain.

(1) Anal fissure (usually because of constipation).


Constipation is one of The most common causes of anal fissures. Anal fissures are common because many suffer from IBS or chronic idiopathic constipation (ref).

An anal fissure is a tear in the lining of the last part of the anal canal.

It can cause severe anal pain, lower back pain, and blood in your stool.


How to suspect anal fissures:


  • Anal fissures can cause lower Back pain and bright red blood in the stool.
  • The main sign is anal pain, which increases during defecation.
  • Pain may also be felt in the buttocks, upper posterior thighs, or lower Back.
  • The blood in your stool is bright red, small in amount & may be seen in the toilet paper or on the outside of the stool.

What to do:


1. Confirm: consult your doctor if you have signs or risk factors (especially constipation).


2- soften your stools: stay hydrated, eat more fiber, take a stool softener, or take a fiber supplement.


3- Relive pain & spasm: Ask your doctor about topical pain relievers Las Lidocaine) & agents that decrease sphincter spasm (such as nitroglycerin or Hydrocortisone creams).


The fissure usually heals in days or a few weeks, Avoiding risk factors such as constipation can help you.


Learn More

(2) Proctitis (Inflammation of your rectum).


Proctitis (inflammation of your rectum) or procto-sigmoiditis (Inflammation of both rectum and sigmoid colon). The Inflamed mucosa may ulcerate and cause blood in the stool (ref).


Proctitis can cause both drops of blood in stool and lower Back pain (usually to The left side). Common causes include. –


1- Infections: such as sexually transmitted diseases


(gonorrhea, genital herpes, chlamydia infection). Also, infections such as salmonella, Bacillary dysentery, & Campylobacter infection.


2- Inflammatory bowel disease (IBD): see later.


3- Some medications: suspect if you recently used antibiotics


4- Rectall radiotherapy & others. Learn more here.


How to suspect:

  • Dysentery: if you have a sudden o set of diarrhea  with mucous and blood in the stool
  • Abdominal pain, with or without fever.
  • Recent use of medications (especially antibiotics).
  • History of IBD or STDs.

(3) Rectal ulcers.


A rectal ulcer is a painful sore that develops inside your rectum. Common causes include (ref).

  • Constipation & straining (as with IBS constipation or chronic idiopathic constipation.
  • Solitary rectal ulcer syndrome: ulcers with unknown cause. 
  • IBD (Crohn’s or ulcerative colitis).

How to suspect: –

  • Pain in the rectum can radiate into your Back.
  • Painful Bowel movement (as with anal fissures).
  • Bleeding from the ianus or Bloody stool.
  • A sense of incomplete evacuation (Tenesmus).

It is difficult to tell the difference between rectal ulcers and anal fissures. Seek help from your doctor.

(4) Large or Bleeding rectal polyp.


A colon polyp is a small clump of cells that grow from the lining of your colon or rectum (Ref).

Typically, colon & rectal polyps are asymptomatic. But a polyp that is large enough and lies distally in the sigmoid colon can ulcerate and bleed into stools.

Large distal colon polyps can ulcerate & get inflamed.

How to suspect:


  • Blood in your stool.
  • Pain inside your rectum (which can be radiated into your lower Back).
  • Risk factors such as obesity, smoking, and older than 50.
  • Family history or past personal history of colon polyps.

Rectal and colon polyps are usually harmless but can potentially become colon cancer. Consult your doctor if you have suspicious signs or risk factors of rectal or sigmoid polyp bleeding.

Learn More


(5) Colorectal cancer.

Colorectal cancers are the second most common cause of cancer deaths in men (& the third in women) in The USA. Approximately 4.2% of people will be diagnosed with colorectal cancer at some point (ref).


You should not panic and expect the worst scenario about the blood in the stool, especially if you’re younger than 50 (More than 90% of cases are above 50).

Cancer in the last part of your colon or rectum can cause low Back pain and blood in the stool. But it is still rare compared to other causes such as fissures, inflammations, or ulcers of The rectum.

How to suspect:(Red Flags)

  • Change in your Bowel habits: AKA having recurrent or chronic diarrhea or constipation.
  • Pain: abdominal pain (which can also progress to your lower Back), but many cases are painless.
  • Blood in stool: is common with colorectal cancer. It can be large in amount, bright red or Black (melena).
  • Unexplained anemia.
  • Unexplained weight loss.
  • Unexplained or prolonged fever.
  • Being older (older than 40-50).
  • Family history of colorectal cancer.
  • You have a history of colon polyps (especially if they were numerous) or familial polyposis.

Consult your doctor if you have multiple risky signs or factors enlisted above.

Your doctor may ask to perform a colonoscopy, sigmoidoscopy, or barium enema t diagnose the cause of blood in the stool. If you are younger than 40, the risk of colorectal cancer is very low.

Learn More.


(6) IBD (Ulcerative Colitis or Crohn’s).


Inflammatory Bowel Disease is used to describe one of two conditions: –

A. Ulcerative Colitis:

A long-lasting inflammation of the inner layer of the colon and rectum

B. Crohn’s Disease:

Inflammation of any part of your digestive tract often spreads deep into affected tissues. (anywhere from the mouth to the ianus),

IBD is a relatively common disease; in the USA, about 1.3% of US adults (3 million) reported being diagnosed (ref).

IBD can cause blood and mucus in your stool. Also, it can lead to abdominal pain, which can propagate to your lower Back.

How to suspect IBD:

  • Having chronic diarrhea with mucous or blood.
  • Chronic fever and fatigue.
  • Recumbent abdominal pain, cramps, Back pain.
  • Unexplained fever, weight loss, or anemia.
  • Reduced a petite.
  • Being younger than 30: Most new cases are diagnosed under 30 (but it can occur in older ages as well).
  • Cigarette smoking or NSAID abuse (such as ibuprofen).
  • Having a family history of IBD
  • Being white or Ashkenazi Jewish.

Learn More.



Hemorrhoids are an extremely common cause of blood in the stool.

Hemorrhoids rarely cause lower Back pain. And that’s why it came late in the list of causes of Bloody poop and lower Back pain.

However, inflamed & swollen hemorrhoids can lead to lower back pain and blood in the stool (ref).

Internal hemorrhoids are more likely to cause lower back pain than external hemorrhoids.

Consider hemorrhoids as a cause of your Condition if you have chronic constipation and straining.


(8) Diverticular disease


Diverticula are small sac-like bulges in the wall of your Colon & rectum. Occasionally, it can be inflamed (Diverticulitis) or form an abscess which leads to abdominal pain and blood in the stool.

Diverticular disease or diverticulitis commonly cause left lower abdominal pain, which also can radiate to your Back.

It is uncommon for diverticular disease to exclusively cause pain in your lower back.

How to suspect:

  • Left lower quadrant pain. (most common site), but it can occur in any part of your abdomen & Back.
  • Fever may occur.
  • Nausea or vomiting.
  • Abdominal tenderness
  • Blood, mucous, or pus in the stool.

Seek help if you are experiencing constant & unexplained abdominal or back pain for days. LEARN MORE HERE.


(9) Just a Random Association.

Instead of thinking of what can cause lower back pain and blood in stool at the same time. You can think of another relatively common scenario: the random association.

For Example, simultaneously having chronic lower back pain (as with lumbar disc problems) and blood in stools ( due to piles or dysentery).

In other words, it is possible to have two separate causes. One for your lower Back pain and the other for blood in the stool.

Usually, one of The two conditions is chronic, and the other is recently experienced where there is no actual link between your blood in stool & lower back pain except TIME.




Blood in stool is a cause of concern. If you are unsure about your condition or have any red flags, please seek help from your doctor immediately.

Red Flags that require immediate medical attention for bloody poop & lower Back pain include:

l- the passage of a large amount of dark blood in the stool (Melena).

2 . Dizziness or shortness of breath.

3- Persistent fever or vomiting for days.

4- Personal or Family history of colon polyps, Colon cancer, or IBD.

5. Age is older than 50 years.

6- Unexplained Anemia or weight loss.