What organ would cause pain on your left side? A comprehensive guide

September 27, 2025 •

3 min read

Pain on the left side is a common and concerning symptom, with a wide range of potential origins. This authoritative guide explores what organ would cause pain on your left side and helps you distinguish between common irritations and serious medical emergencies based on location and accompanying signs.

Quick Summary

Pain on the left side can stem from a variety of organs and systems, including the spleen, pancreas, stomach, and left kidney in the upper abdomen. In the lower region, potential sources involve the colon and, for women, the reproductive organs. Other possibilities include musculoskeletal or cardiac issues.

Key Points

Upper Left Pain: Consider the spleen, stomach, pancreas, and left kidney as potential culprits, often linked to infections, inflammation, or digestive issues.
Lower Left Pain: Frequently involves the colon, particularly diverticulitis, or female reproductive organs like the left ovary and fallopian tube.
Red Flag Symptoms: Severe, sudden, or persistent pain accompanied by fever, nausea, dizziness, or bloody stools requires immediate medical evaluation.
Cardiac vs. Gastrointestinal: Upper left pain near the chest can be cardiac-related (heart attack, pericarditis), making an accurate assessment of all symptoms critical.
Musculoskeletal Issues: Pain can sometimes originate from strained muscles or rib injuries, mimicking internal organ problems.
Seek Professional Help: While self-assessment can provide clues, only a healthcare professional can provide a definitive diagnosis and proper treatment plan.

Understanding the Anatomy of Your Left Side

To identify what organ would cause pain on your left side, it's helpful to understand the basic anatomy. The left side of your torso houses several important organs, which can be broadly divided into the upper and lower quadrants.

Upper Left Quadrant

This area, located just below the ribs, includes the:

Spleen: A small organ that filters blood and supports the immune system.
Pancreas: Produces digestive enzymes and hormones like insulin. The tail of the pancreas extends into the left side.
Stomach: The main portion of the stomach is in the upper left abdomen.
Left Kidney: Positioned toward the back, under the rib cage.
Left Lobe of the Liver: Although mostly on the right, a small portion can extend left.
Portion of the Colon (splenic flexure): Where the large intestine bends sharply near the spleen.

Lower Left Quadrant

This area, below the navel on the left side, contains the:

Left Side of the Colon: Including the descending colon and sigmoid colon.
Small Intestine: Portions of the small intestine pass through this area.
Left Ureter: The tube connecting the left kidney to the bladder.
Left Ovary and Fallopian Tube: (in females).

Specific Organs and Conditions Causing Upper Left Pain

Spleen-Related Pain

An enlarged spleen can cause pain or discomfort under the left ribs, often with a feeling of fullness. A ruptured spleen, often due to injury, causes severe, sharp pain and is a medical emergency.

Pancreatitis

Inflammation of the pancreas can cause severe pain in the upper left or middle abdomen, sometimes radiating to the back. Symptoms include nausea, vomiting, fever, and pain that may worsen after eating.

Stomach Conditions

Conditions affecting the stomach like gastritis (inflammation) or ulcers can cause burning or gnawing pain in the upper abdomen. Indigestion with bloating is a common, less serious cause.

Left Kidney Issues

Kidney stones cause severe, crampy pain in the flank or back that can move to the abdomen or groin. A kidney infection can cause a steady ache in the flank, fever, and painful urination.

Specific Organs and Conditions Causing Lower Left Pain

Diverticulitis

This common cause, especially in those over 40, involves inflamed colon pouches. It causes persistent lower left abdominal pain, sometimes with fever.

Colon Conditions

Inflammatory Bowel Disease (IBD) can cause lower abdominal pain, cramping, and changes in bowel habits. Constipation can also lead to cramping and discomfort on the left side.

Female Reproductive Organs

Conditions like ovarian cysts, endometriosis, or an ectopic pregnancy can cause pain on the left side in women.

Pinpointing the Cause: A Comparison Table


Feature	Upper Left Abdominal Pain	Lower Left Abdominal Pain
Associated Organs	Spleen, pancreas, stomach, left kidney, left lobe of liver, parts of colon.	Left side of colon, small intestine, left kidney (ureter), left ovary/fallopian tube.
Common Causes	Gastritis, pancreatitis, enlarged spleen, kidney issues, indigestion.	Diverticulitis, constipation, IBD, ovarian cysts, ectopic pregnancy (in women).
Type of Pain	Can be burning, severe, radiating to back, or dull ache.	Often cramping, persistent, or sharp.
Other Symptoms	Nausea, vomiting, fever, bloating, fullness, indigestion.	Fever, nausea, changes in bowel habits, pelvic pressure, painful urination.
Emergency Concern	Severe pain, radiating to back or arm, shortness of breath, high fever.	Severe, sudden pain, fever, bloody stools, dizziness.

Non-Organ Related Causes

Left-sided pain isn't always from an internal organ. Heart and lung issues like heart attacks, pericarditis, pneumonia, or pulmonary embolism can cause pain in the chest or under the ribs. Musculoskeletal problems like strained muscles, rib injuries, or costochondritis can also mimic organ pain.

When to Seek Medical Attention

While some causes are mild, seek immediate medical care for:

Sudden, severe, or worsening pain.
Pain with fever, nausea, or vomiting.
Bloody or black, tarry stools.
Dizziness, lightheadedness, or rapid heart rate.
Difficulty breathing or chest pain.
Unexplained weight loss or pale stools.

For a complete overview of gastrointestinal health, consult reliable sources such as the National Institute of Diabetes and Digestive and Kidney Diseases.

Conclusion

Identifying the specific organ that would cause pain on your left side requires careful consideration of the pain's location, intensity, and accompanying symptoms. While minor issues like gas or indigestion are common, conditions involving the pancreas, spleen, kidneys, and colon, or even the heart, can be serious. Paying close attention to your body's signals and seeking professional medical advice for persistent or severe symptoms is the safest course of action.

Frequently Asked Questions

Pain under the left rib cage could be caused by the spleen, pancreas, or stomach. Conditions like an enlarged spleen, pancreatitis, or gastritis are common causes in this region.

No, left-sided pain is not always serious. Common and non-serious causes include gas, indigestion, or constipation. However, severe, persistent, or accompanied by other symptoms like fever or vomiting, it could indicate a more serious condition.

Yes. Heart conditions, including a heart attack, can cause pain in the upper left side of the chest that may sometimes radiate to the abdomen or back.

Kidney pain from issues like stones or infections is typically a dull ache in the flank or back, just under the ribs. It can radiate to the front or groin and is often accompanied by other symptoms like fever, painful urination, or bloody urine.

Diverticulitis is the inflammation of small pouches (diverticula) that develop in the colon. These pouches are most common on the left side of the colon, so when they become infected, they cause pain and inflammation in the lower left abdomen.

In addition to general organ-related causes, women may experience left-sided pain from conditions affecting the left ovary or fallopian tube, such as ovarian cysts or endometriosis. An ectopic pregnancy can also cause severe left-sided pain.

Yes, stress and anxiety can contribute to various physical symptoms, including abdominal pain. Stress can worsen conditions like Irritable Bowel Syndrome (IBS) or indigestion, which can manifest as left-sided pain or cramping.