What does sudden side pain mean? A guide to potential causes and when to seek medical help

October 2, 2025 •

4 min read

Over one million people in the U.S. each year are affected by kidney stones, which can cause agonizing side pain. While this sharp sensation is a common culprit, what does sudden side pain mean in a broader sense? It could stem from a variety of sources, ranging from harmless gas to life-threatening emergencies requiring immediate medical attention.

Quick Summary

Sudden side pain can originate from mild issues like muscle strain or gas, or more serious conditions affecting organs like the kidneys, appendix, or gallbladder. Identifying the pain's location and accompanying symptoms is key to determining the cause and whether immediate medical care is necessary.

Key Points

Location Matters: The side of your body where you feel pain can indicate which organ or system is affected, from the appendix on the lower right to the spleen on the upper left.
Not All Pain is an Emergency: Mild, temporary pain from gas, muscle strain, or exercise-related side stitches is common and typically resolves on its own with rest.
Watch for Red Flags: Severe, persistent, or worsening pain, especially with fever, vomiting, or other concerning symptoms, warrants immediate medical attention.
Kidney Stones are Painful: Excruciating, wave-like pain in the flank that radiates to the groin is a classic sign of kidney stones and often requires a hospital visit.
Pregnancy Has Unique Causes: During pregnancy, common culprits like round ligament pain or constipation are normal, but severe or persistent pain could signal more serious issues like an ectopic pregnancy.
Appendicitis is a Medical Emergency: Pain that starts near the navel and shifts to the lower-right abdomen, often with nausea and fever, should be evaluated promptly for appendicitis.

Side pain, medically known as flank pain or abdominal pain, can be a disconcerting experience due to the many organs housed within the trunk. The discomfort can manifest in different ways, from a mild, fleeting cramp to an intense, persistent ache. Understanding the possible origins and identifying associated symptoms is critical for knowing how to respond appropriately.

Common Causes by Location

The location of the pain is a vital clue for healthcare professionals, as it often corresponds to underlying issues with specific organs in that area.

Pain on the Right Side

The right side of the abdomen and flank contains several key organs, including the appendix, gallbladder, liver, and right kidney.

Appendicitis: One of the most serious causes of right-sided pain, appendicitis often begins as a dull ache near the navel that shifts to the lower-right abdomen and becomes sharper. It is frequently accompanied by nausea, vomiting, loss of appetite, and a low-grade fever. A worsening pain that is localized and sensitive to touch is a major warning sign.
Gallstones (Biliary Colic): These hardened deposits can block the bile duct, causing intense, crampy pain in the upper-right abdomen. This pain, which may radiate to the back or shoulder, can last for hours and is often triggered by eating fatty foods. Fever, nausea, and vomiting can also occur.
Hepatitis: Inflammation of the liver can cause pain in the upper-right abdomen, along with fatigue, nausea, and jaundice (yellowing of the skin or eyes).

Pain on the Left Side

The left side of the body houses the spleen, pancreas, parts of the stomach, and the left kidney.

Diverticulitis: This condition involves the inflammation of small pouches that form in the colon, typically causing severe and persistent pain in the lower-left abdomen. Other symptoms include fever, nausea, and changes in bowel habits.
Pancreatitis: Inflammation of the pancreas can lead to severe pain in the upper abdomen that radiates to the back. Nausea, vomiting, and fever are common accompanying symptoms.
Spleen Issues: An enlarged or damaged spleen in the upper-left abdomen can cause pain or tenderness. A ruptured spleen, often caused by trauma, is a medical emergency.
Gas: A common and harmless cause, trapped gas can produce sharp, cramping pain that may shift location. It often resolves on its own or after passing gas.

Pain in the Flank (Back & Sides)

Pain felt in the lower back between the ribs and hips is known as flank pain and is often related to the kidneys or urinary tract.

Kidney Stones: These mineral deposits can cause excruciating, wave-like pain in the back and side that may radiate to the lower abdomen and groin as the stone moves. Symptoms may also include blood in the urine, nausea, vomiting, and painful urination.
Kidney Infection: A urinary tract infection that travels to the kidneys can cause flank pain, along with fever, chills, and painful urination.
Muscle Strain: Overuse or injury of back and side muscles, often from physical activity or awkward movements, can cause localized pain that worsens with movement.

Side Pain During Pregnancy

In pregnancy, sudden side pain can be caused by normal changes or more serious complications.

Round Ligament Pain: The stretching of ligaments supporting the growing uterus can cause sharp, jabbing pains, especially in the second trimester. The pain is usually brief and can be triggered by sudden movements.
Ectopic Pregnancy: This is a medical emergency involving a fertilized egg implanting outside the uterus. It can cause sharp, one-sided abdominal pain, vaginal bleeding, and dizziness.

Exercise-Related Side Pain (Side Stitches)

Side stitches, or exercise-related transient abdominal pain (ETAP), are a common and harmless issue during physical activity, especially running. Several theories suggest they are caused by diaphragm spasms, ligament stress, or shallow breathing.

Comparing Different Causes of Sudden Side Pain


Condition	Typical Location	Pain Quality	Associated Symptoms	Urgency
Appendicitis	Lower-right abdomen, starts near navel	Sharp, worsening	Nausea, vomiting, low fever	High (Medical Emergency)
Kidney Stone	Side and back (flank), can radiate to groin	Intense, wave-like	Nausea, vomiting, blood in urine	High (ER recommended)
Diverticulitis	Lower-left abdomen	Severe, persistent	Fever, chills, change in bowel habits	High (Medical Evaluation)
Gallstones	Upper-right abdomen	Cramping, can radiate to back	Nausea, vomiting, triggered by fatty meals	Medium to High (Medical Evaluation)
Side Stitch	Under the ribcage, on one side	Sharp, precise	Breathlessness, occurs during exercise	Low (Resolves with rest)
Gas Pain	Can be anywhere in abdomen	Cramping, inconsistent	Bloating, burping, flatulence	Low (Resolves naturally)

When to Seek Medical Help

While many causes of side pain are not serious, it is vital to know when to seek professional medical advice. A visit to your doctor is warranted if the pain is persistent or accompanied by other symptoms. However, certain "red flag" symptoms require immediate emergency medical attention.

Call 911 or go to the emergency room if you experience sudden side pain with any of the following:

Severe, unbearable pain that comes on suddenly
Fever or chills
Nausea and vomiting that won't go away
Bloody or black stools
Abdominal swelling or tenderness to the touch
Pain that worsens with movement
Sudden chest pressure or pain, as this could indicate a heart attack or pulmonary embolism
If you are pregnant, severe pain could indicate a serious complication

Conclusion

Sudden side pain is a broad symptom with many potential origins. Paying close attention to the pain's location, quality, and accompanying symptoms can provide crucial clues. While common culprits like gas or exercise-induced side stitches are usually benign, conditions like appendicitis, kidney stones, or a pulmonary embolism require swift medical care. If the pain is severe, persistent, or accompanied by concerning symptoms, it is always best to consult a healthcare professional for an accurate diagnosis and treatment plan.

For more information on abdominal pain, including signs and when to seek medical help, visit the reputable sources cited in this article such as the Mayo Clinic.

Frequently Asked Questions

Sudden right-side pain can be caused by appendicitis, gallstones, liver issues, kidney stones, or gas. The specific location (upper vs. lower) and associated symptoms are important clues for diagnosis.

Left-sided abdominal pain can be linked to diverticulitis, pancreatitis, issues with the spleen, kidney stones in the left kidney, or simple gas buildup.

Go to the ER if side pain is severe, comes on suddenly, worsens rapidly, or is accompanied by fever, persistent vomiting, bloody stools, or abdominal swelling. These can be signs of a medical emergency like appendicitis or a ruptured organ.

Yes, exercise-induced side pain, known as a side stitch, is common during physical activities like running. It is typically a harmless, sharp pain under the ribcage that resolves with rest, controlled breathing, and stretching.

Pain from a kidney stone is often sharp, severe, and comes in waves. It is typically felt in the flank area (side and back) and may travel to the lower abdomen and groin. Other signs include blood in the urine, nausea, and vomiting.

Side pain is a general term for pain in the side or abdomen. Flank pain specifically refers to pain in the area between the ribs and the hip, often indicating an issue with the kidneys or lower back.

Mild side pain from round ligament stretching or constipation can be normal during pregnancy, especially in the second trimester. However, severe or persistent pain, especially with bleeding, requires immediate medical attention to rule out serious conditions.