Why do I feel a bulge on my left side? Causes and what to do

September 29, 2025 •

4 min read

According to Mayo Clinic, hernias are a common cause of abdominal bulges, often caused by increased pressure within the abdomen. When you feel a bulge on your left side, the cause could range from a simple muscle strain to something more serious like a hernia or an enlarged organ. Understanding the potential reasons behind this symptom is the first step toward finding relief and deciding on the best course of action.

Quick Summary

A bulge on the left side can stem from various causes, including hernias where internal tissue pushes through weakened muscle, harmless fatty lumps called lipomas, or swelling from digestive issues. Less common but more serious reasons can involve an enlarged spleen or even an abdominal aortic aneurysm, making medical evaluation crucial for proper diagnosis.

Key Points

Causes Vary: A bulge on the left side can range from a common hernia or a harmless fatty lump (lipoma) to more serious conditions like an enlarged spleen or diverticulitis.
Seek Medical Advice: Any unexplained bulge should be evaluated by a doctor for an accurate diagnosis and to rule out potentially serious issues.
Urgent Symptoms: Seek immediate medical care if the bulge is accompanied by severe pain, fever, vomiting, or if it appears dark or purple.
Left Side Organs: The left abdomen contains the stomach, spleen, and a portion of the colon, among other structures, so the location of the bulge can be a clue.
Diagnostic Tools: A doctor will use physical exams, imaging tests like ultrasounds or CT scans, and sometimes a biopsy to determine the cause.
Not Always Dangerous: Many abdominal bulges, such as lipomas, are benign and may not require treatment. However, conditions like a strangulated hernia are life-threatening.

Understanding the Left Side of Your Abdomen

Your left side houses several important organs and structures, including the stomach, spleen, colon, left kidney, pancreas, and a portion of your small intestine. The location and characteristics of a bulge can offer important clues about its origin, though a professional medical diagnosis is always necessary. Common benign causes include lipomas and cysts, while more serious possibilities include various types of hernias or an enlarged spleen.

Potential Causes of a Bulge on the Left Side

1. Hernias

A hernia is one of the most frequent causes of a bulge, and it occurs when an organ or tissue bulges through a weak spot in the muscle or tissue that contains it. Different types can manifest on the left side:

Inguinal Hernia: Although more common in the groin, a left-sided inguinal hernia can cause a bulge in the groin area when tissue pushes into the inguinal canal.
Incisional Hernia: If you have had previous abdominal surgery, an incisional hernia can occur where the surgical scar has weakened the muscle wall.
Ventral Hernia: This can happen anywhere along the midline of the abdomen, including the left side. It's often caused by strain from heavy lifting or persistent coughing.
Hiatal Hernia: This occurs when part of the stomach pushes up through the diaphragm and into the chest cavity, potentially causing a bulge in the upper abdomen and symptoms like heartburn.

2. Enlarged Spleen (Splenomegaly)

Located under the left rib cage, an enlarged spleen can cause a feeling of fullness, pain, or a palpable mass in the upper left abdomen. This can be caused by infections like mononucleosis, liver disease, blood cancers, and other conditions.

3. Lipomas and Cysts

Lipoma: A lipoma is a benign, fatty lump that grows slowly under the skin. They are often soft, movable, and typically harmless.
Cyst: These are fluid-filled sacs that can form anywhere on the body, including the abdominal wall, and are generally harmless unless they grow large or become infected.

4. Digestive System Issues

Constipation: A buildup of stool can cause bloating and a sensation of a mass or fullness, often resolving once the constipation is relieved.
Diverticulitis: The inflammation or infection of small pouches (diverticula) in the colon wall can lead to pain, swelling, and a palpable mass, especially on the left side of the lower abdomen.
Crohn's Disease: This inflammatory bowel disease can lead to thickened bowel loops and abdominal masses, often accompanied by other gastrointestinal symptoms.
Abscess: A pocket of pus from an infection can form inside the abdominal cavity, sometimes appearing after a surgical procedure.

5. Other Less Common Causes

Abdominal Aortic Aneurysm (AAA): While less common, a pulsating bulge in the abdomen could indicate an enlarged or weakened aorta. This is a medical emergency and requires immediate attention.
Cancer: In rare cases, a tumor on an organ like the kidney, spleen, or colon could present as a mass. This is often associated with other symptoms like unexplained weight loss or changes in bowel habits.
Hematoma: An injury to the abdominal area can cause broken blood vessels to leak, forming a pool of blood (hematoma) that can feel like a lump.

How a Doctor Diagnoses a Left-Sided Bulge

When you see a healthcare professional for a left-sided bulge, they will likely start with a physical exam and a detailed medical history. This may be followed by various diagnostic tests to determine the precise cause:

Imaging Tests: An ultrasound is often the first step, providing a real-time view of your internal organs and tissues. A CT scan or MRI may be used for a more detailed look.
Blood Tests: These can help identify infections, inflammation, or issues with organ function.
Biopsy: If a tumor is suspected, a small tissue sample may be taken for laboratory analysis.

Comparison of Common Causes


Feature	Hernia	Lipoma	Enlarged Spleen	Diverticulitis	Hematoma
Sensation	Often a visible bulge, may ache or burn.	Soft, rubbery, and movable lump under the skin.	Fullness or pain under the left rib cage.	Pain, tenderness, and sometimes fever.	Firm, bruised, and tender area after injury.
Appearance	More obvious when standing, coughing, or straining.	Round or oval lump just beneath the skin.	Bulge in the upper left abdomen, may be subtle.	Swelling in the lower left abdomen.	Discolored or bruised skin over a firm lump.
Location	Groin (inguinal), near a surgical scar (incisional), midline abdomen (ventral).	Anywhere on the abdomen.	Upper left abdomen, under the ribs.	Lower left abdomen.	Site of recent injury.
Associated Symptoms	Pressure, discomfort, potential bowel obstruction.	Usually none, unless it grows very large.	Anemia, fatigue, frequent infections.	Abdominal pain, fever, nausea, changes in bowel habits.	Pain, discoloration, swelling.

When to See a Doctor

While some abdominal bulges are benign, others require prompt medical attention. It is always wise to consult a doctor if you discover an unexplained bulge. Seek immediate medical care (call 911) if your bulge is accompanied by any of the following symptoms:

Severe, sudden pain
Nausea and vomiting
A bulge that turns red, purple, or dark
Fever
Inability to have a bowel movement or pass gas
A pulsating mass

Conclusion

Feeling a bulge on your left side can be concerning, but it's important to remember that not all masses are serious. The key is to pay attention to your body and seek professional medical advice for an accurate diagnosis. Conditions like hernias, lipomas, or digestive issues are common, but ruling out more severe causes like an enlarged spleen or an abdominal aortic aneurysm is vital for your health. A healthcare provider will be able to perform the necessary examinations and tests to provide a clear answer and a proper treatment plan. For more general information on abdominal health, you can visit the Cleveland Clinic's health library.

Disclaimer: This article is for informational purposes only and does not constitute medical advice. Please consult a qualified healthcare professional for diagnosis and treatment.

Frequently Asked Questions

The most common cause is often a hernia, where internal tissue pushes through a weak spot in the abdominal muscle wall. Other frequent, less serious causes include lipomas (harmless fatty lumps).

Yes, an enlarged spleen (splenomegaly) can cause a palpable mass or feeling of fullness under the left rib cage. This can be caused by infections, liver disease, or blood disorders and requires medical evaluation.

While a soft, movable lump is often a harmless lipoma, a doctor should always evaluate any new mass to confirm the diagnosis and rule out other possibilities.

You should be worried if the bulge is accompanied by severe pain, fever, nausea, vomiting, or if the bulge appears red, purple, or dark. These could be signs of a serious condition like a strangulated hernia.

Yes, a buildup of stool from constipation can cause bloating and a sensation of a mass or fullness in the abdomen, including on the left side. This feeling should subside once the constipation resolves.

A doctor will typically start with a physical exam and medical history. They may then order imaging tests such as an ultrasound, CT scan, or MRI to get a better view of the abdominal structures.

While it's rare, a bulge can sometimes indicate a tumor on an organ within the abdomen. This is why medical evaluation is so important, especially if the bulge is accompanied by other symptoms like unexplained weight loss or a change in bowel habits.