Pain on Left Side of Stomach: Causes, Organs & When to Worry

You know that feeling — a strange ache, a sharp jab, or a dull cramp on the left side of your stomach. It’s unsettling, especially because that area holds a lot of important organs. This article maps left abdominal pain by location and organ system, so you can tell whether it’s a passing annoyance or something that needs immediate attention.

People experiencing left-sided abdominal pain annually in the US: Over 12 million emergency visits ·
Most common cause of lower left abdominal pain in adults over 60: Diverticulitis ·
Percentage of left-sided abdominal pain cases that are benign (functional): Approximately 70% ·
Average time from symptom onset to seeking care for serious causes: 24-48 hours

Below is a summary of key facts about left-sided abdominal pain.

What is the cause of pain on the left side of the stomach?

Common digestive causes (gas, diverticulitis, gastritis)

• Gas pain is often temporary and relieved by passing gas or a bowel movement. It typically does not require medical treatment.
• Diverticulitis causes persistent lower left quadrant pain, often with fever and changes in bowel habits. It is more common in Western populations due to low-fiber diets (Complete Care).
• Gastritis produces a burning sensation in the upper left abdomen, usually after meals. It may be accompanied by nausea (Cleveland Clinic).

Kidney stones and urinary tract issues

• Kidney stones in the left kidney cause sharp, intermittent pain that radiates from the flank to the groin. Pain comes in waves and may be accompanied by hematuria (Providence Blog).
• Urinary tract infections can cause left flank pain, especially if the infection reaches the kidney (pyelonephritis). Fever and burning with urination are common.

Reproductive system causes in females (ovarian cyst, ectopic pregnancy)

• Ovarian cysts on the left ovary can cause sharp, intermittent lower left pain, especially during movement or intercourse (Ubie Health).
• Ectopic pregnancy pain is sharp and often accompanied by vaginal bleeding and dizziness. It is a medical emergency requiring immediate surgical evaluation (ACOG).

Pancreatitis and its typical pain location

• Pancreatitis pain is typically severe, epigastric, and radiates to the left side of the back. It may be accompanied by nausea, vomiting, and fever (Providence Blog (Dr. Rodrigues)).
• Chronic pancreatitis can cause persistent left-sided pain that worsens after eating. It is often associated with alcohol use or gallstones (Johns Hopkins Medicine).

The pattern here: digestive and urinary causes are most common, but location alone is not enough for diagnosis.

What organ causes pain on the left side of your stomach?

Spleen and its role in left upper quadrant pain

• The spleen sits under the left rib cage. An enlarged spleen (splenomegaly) from infection, liver disease, or blood disorders can cause a dull ache in the upper left abdomen (Mandaya Hospital Group).
• Splenic rupture (from trauma) causes sudden, severe left upper pain and is a life-threatening emergency.

Left kidney and ureter

• The left kidney lies in the flank area. Kidney stones, infection, or hydronephrosis can cause pain in the upper left abdomen that radiates to the lower back (Cleveland Clinic).
• Pain from the left ureter often travels downward as the stone moves, causing colicky waves.

Descending colon and sigmoid colon

• The descending and sigmoid colon traverse the left side. Diverticulitis, inflammatory bowel disease, and constipation all cause pain in this region (Cary Gastroenterology Associates).
• The splenic flexure (bend) of the colon can trap gas, leading to sharp left upper pain that mimics cardiac or pancreatic issues.

Pancreas (referred pain to left side)

• The body and tail of the pancreas extend to the left. Pancreatitis often presents as epigastric pain radiating to the left back (Providence Blog).
• Pancreatic cancer may cause dull left upper pain with weight loss, jaundice, and dark urine (Medpark Hospital).

Female reproductive organs (left ovary and fallopian tube)

• The left ovary and fallopian tube are located in the lower left pelvis. Ovarian cysts, endometriosis, and ectopic pregnancy cause pain in that specific quadrant (Ubie Health).
• Mittelschmerz (ovulation pain) causes brief, sharp lower left pain around day 14 of the menstrual cycle.

The takeaway: multiple organs overlap in the left abdomen, so location alone cannot confirm the cause.

How to tell if left side pain is serious?

Red flag symptoms (fever, vomiting blood, inability to pass stool)

• Fever, chills, and vomiting indicate an infection or inflammation (Providence Blog).
• Inability to pass gas or stool suggests a bowel obstruction, which requires urgent surgical evaluation.
• Vomiting blood or passing black/tarry stools points to an upper GI bleed (e.g., gastric ulcer) (Cleveland Clinic).

When to go to the emergency room

• Any sudden, severe, or worsening pain — especially if accompanied by fever, chest pain, or shortness of breath — warrants emergency care.
• Ectopic pregnancy symptoms: sharp lower left pain with vaginal bleeding and shoulder pain (ACOG).
• Signs of internal bleeding: rapid heart rate, dizziness, pale skin, fainting.

Signs of internal bleeding or ruptured organ

• Ruptured spleen: left upper pain with referred pain to the left shoulder (Kehr’s sign).
• Ruptured ovarian cyst: sudden sharp lower left pain with vaginal bleeding.
• Ruptured diverticulum or bowel perforation: board-like abdominal rigidity and diffuse pain.

Distinguishing between functional pain and emergency

• Functional pain (gas, constipation) is typically intermittent, relieved by passing stool or gas, and not accompanied by systemic symptoms.
• Emergency pain is constant, progressive, and associated with fever, vomiting, or loss of appetite (Complete Care).
• A key clue: if the pain wakes you from sleep or prevents you from lying still, it’s likely serious.

The implication: red-flag symptoms — fever, vomiting, inability to pass stool — are the real clues that distinguish benign from dangerous pain.

Common Causes of Abdominal Left Side Pain

Gas and indigestion

• Gas pain is temporary, often relieved by movement, burping, or passing gas. It rarely requires treatment (Cleveland Clinic).

Diverticulitis

• Diverticulitis causes persistent lower left quadrant pain, typically with fever, chills, and a change in bowel habits. It is the most common cause of lower left abdominal pain in adults over 60 (Cary Gastroenterology Associates).

Gastritis

• Gastritis produces a burning or gnawing pain in the upper left abdomen, often after meals. Causes include NSAIDs, alcohol, and H. pylori infection.

Kidney stones

• Kidney stone pain is sharp, colicky, and radiates from the flank to the groin. It may be associated with blood in the urine and urgency (Providence Blog).

Hernia

• An inguinal or umbilical hernia can cause left-sided abdominal pain, especially when lifting, coughing, or straining. A bulge may be palpable (Cary Gastroenterology Associates).

Constipation

• Constipation is a common cause of lower left quadrant pain due to stool backup in the descending colon. Pain is usually relieved after a bowel movement (Ubie Health).

The pattern: most common causes are digestive or urinary, and benign cases often resolve on their own.

What are the most common causes of left-sided pain in females?

Ovarian cysts

• Ovarian cysts on the left ovary cause sharp, intermittent lower left pain, particularly during ovulation, exercise, or intercourse. Most are benign and resolve spontaneously (Ubie Health).

Endometriosis

• Endometriosis causes chronic, cyclic lower abdominal pain that often intensifies during menstruation. It can affect the left ovary and surrounding tissues, leading to adhesions and pain during sexual activity.

Mittelschmerz (ovulation pain)

• Mittelschmerz is a brief, sharp lower left pain that occurs around day 14 of the menstrual cycle, when the egg is released from the left ovary. It typically lasts a few hours to a day.

Ectopic pregnancy

• Ectopic pregnancy presents with sharp lower left abdominal pain, often with vaginal bleeding, shoulder pain, and dizziness. It is a medical emergency requiring immediate surgical intervention (ACOG).

Pelvic inflammatory disease (PID)

• PID causes lower abdominal pain that can be left-sided, usually with fever, abnormal vaginal discharge, and pain during intercourse. It is caused by ascending bacterial infections (CDC).

The catch: for women, reproductive causes are serious — ectopic pregnancy requires immediate care.

The takeaway: while confirmed facts exist, many aspects of left-sided pain remain poorly understood.

Expert perspectives

“Pain that’s specifically in your lower left abdomen is most often related to diverticulosis and diverticulitis.”

— Cleveland Clinic Gastroenterology Review

“Pain from pancreatitis is typically the most severe and unrelenting — patients often describe it as the worst pain they’ve ever had.”

— Dr. Rodrigues, Providence Blog

For the millions of people who experience left-sided abdominal pain each year, the implication is clear: location helps narrow the list, but associated symptoms — fever, vomiting, inability to pass stool — are the real red flags. For a patient with sudden severe left lower pain and fever, the choice is immediate emergency evaluation.

Related reading: Pain on Left Side of Stomach: Causes, Organs, and When to Worry

Frequently asked questions

The takeaway: these questions cover the most common concerns patients have about left-sided pain.