Side Pain

Side pain, also known as flank pain, occurs in the area between your lower ribs and hips on either side of your body. This type of pain can range from a mild ache to severe, debilitating discomfort and may be caused by various conditions affecting muscles, organs, or other structures in the area. The location (left or right), nature of the pain, and associated symptoms often provide important clues about the underlying cause. Understanding when side pain is a minor issue versus a medical emergency can help you make informed decisions about seeking care.

Last updated June 9, 2026

🚨 Seek Emergency Care If You Have:

Severe, sudden side pain with fever and chills (kidney infection), right lower side pain with nausea and fever (appendicitis), side pain with blood in urine, severe pain that comes in waves (kidney stones), side pain with dizziness or fainting, or pain after trauma/injury. Also seek immediate care for side pain with difficulty breathing, chest pain spreading to side, or signs of internal bleeding.

Medical Disclaimer: This information is for educational purposes only and should not replace professional medical advice. Always consult with a qualified healthcare provider for diagnosis and treatment of any medical condition.

Understanding Side Pain

Anatomical Considerations

The sides of your body contain various structures that can cause pain:

  • Organs: Kidneys, parts of liver, spleen, intestines
  • Muscles: Abdominal muscles, back muscles
  • Bones: Ribs, spine
  • Nerves: Intercostal nerves, spinal nerves
  • Other structures: Ureters, blood vessels, connective tissue

Types of Side Pain

  • Sharp, stabbing: Often nerve or acute organ issues
  • Dull, aching: Muscular or chronic conditions
  • Cramping: Digestive or menstrual causes
  • Burning: Nerve irritation or inflammation
  • Colicky (waves): Kidney stones or intestinal issues
  • Constant: Infection or inflammation

Location Significance

  • Upper side: Often kidney, liver, or lung-related
  • Middle side: Kidney, muscle, or digestive
  • Lower side: Appendix, ovaries, colon, hip
  • Front to back: Often kidney or muscle

Right Side Pain Causes

Appendicitis

  • Classic presentation:
    • Starts around belly button
    • Moves to right lower side
    • Worsens over hours
    • Fever and nausea
    • Rebound tenderness
    • MEDICAL EMERGENCY

Liver Conditions

  • Hepatitis:
    • Upper right side pain
    • Jaundice (yellowing)
    • Fatigue
    • Nausea
  • Liver abscess:
    • Fever and chills
    • Right upper pain
    • May radiate to shoulder

Gallbladder Problems

  • Gallstones:
    • Right upper side pain
    • After fatty meals
    • Radiates to back/shoulder
    • Nausea and vomiting
  • Cholecystitis:
    • Inflamed gallbladder
    • Severe, constant pain
    • Fever
    • Positive Murphy's sign

Right Kidney Issues

  • Kidney stones
  • Kidney infection
  • Hydronephrosis
  • Renal cyst

Other Right Side Causes

  • Right ovarian cyst (women)
  • Ectopic pregnancy (women)
  • Hernia
  • Pulled muscle
  • Shingles

Left Side Pain Causes

Spleen Problems

  • Enlarged spleen:
    • Left upper side pain
    • Feeling full quickly
    • May indicate infection
  • Ruptured spleen:
    • EMERGENCY
    • After trauma
    • Severe pain
    • Lightheadedness
    • Rapid pulse

Left Kidney Issues

  • Same as right kidney problems
  • Stones, infection, cysts
  • Pain may radiate to groin

Digestive Causes

  • Diverticulitis:
    • Usually left lower side
    • Fever
    • Change in bowel habits
    • Tenderness
  • Irritable bowel syndrome:
    • Cramping pain
    • Bloating
    • Alternating constipation/diarrhea
  • Constipation:
    • Left-sided cramping
    • Bloating
    • Infrequent bowel movements

Other Left Side Causes

  • Left ovarian cyst (women)
  • Endometriosis (women)
  • Pulled muscle
  • Rib injuries
  • Pancreatitis (can be either side)

Common Causes Affecting Either Side

Kidney Stones

  • Symptoms:
    • Severe, colicky pain
    • Comes in waves
    • May radiate to groin
    • Blood in urine
    • Nausea and vomiting
    • Urinary urgency

Kidney Infection (Pyelonephritis)

  • Symptoms:
    • Fever and chills
    • Back/side pain
    • Urinary symptoms
    • Nausea
    • Requires antibiotics

Muscle Strain

  • Common causes:
    • Heavy lifting
    • Twisting movements
    • Poor posture
    • Exercise
    • Coughing fits
  • Characteristics:
    • Worse with movement
    • Tender to touch
    • May have muscle spasm
    • Improves with rest

Shingles (Herpes Zoster)

  • Burning pain along nerve path
  • May precede rash
  • Follows dermatome
  • Blistering rash appears
  • One-sided

Rib Problems

  • Costochondritis: Inflammation of rib cartilage
  • Rib fracture: After trauma or severe coughing
  • Intercostal strain: Muscle between ribs

Referred Pain

  • Pneumonia: Can cause side pain
  • Heart problems: May radiate to left side
  • Spine issues: Can cause side pain

Associated Symptoms and Red Flags

Urinary Symptoms

  • Blood in urine
  • Painful urination
  • Frequent urination
  • Cloudy or foul-smelling urine
  • Inability to urinate

Digestive Symptoms

  • Nausea and vomiting
  • Changes in bowel habits
  • Bloating
  • Loss of appetite
  • Blood in stool

Systemic Symptoms

  • Fever and chills
  • Fatigue
  • Weight loss
  • Night sweats
  • General malaise

Emergency Warning Signs

  • Severe, sudden onset pain
  • High fever (>103°F)
  • Signs of shock (rapid pulse, dizziness)
  • Inability to pass gas or stool
  • Severe abdominal distension
  • Pain after trauma
  • Pregnancy with side pain

Diagnosis and Evaluation

Medical History

  • Pain onset and duration
  • Location and radiation
  • Quality and severity
  • Aggravating/relieving factors
  • Associated symptoms
  • Medical conditions
  • Recent activities

Physical Examination

  • Vital signs
  • Abdominal examination
  • Back examination
  • Percussion for tenderness
  • Special tests (Murphy's sign, etc.)

Diagnostic Tests

  • Laboratory:
    • Complete blood count
    • Urinalysis
    • Liver function tests
    • Kidney function
    • Pregnancy test
  • Imaging:
    • Ultrasound
    • CT scan
    • X-ray
    • MRI

Treatment Approaches

Immediate Care

  • Rest in comfortable position
  • Apply heat or cold
  • Over-the-counter pain relief
  • Stay hydrated
  • Monitor symptoms

Medical Treatments

  • Pain management: NSAIDs, prescription medications
  • Antibiotics: For infections
  • Muscle relaxants: For spasms
  • Specific treatments: Based on diagnosis

When Surgery May Be Needed

  • Appendicitis
  • Gallbladder disease
  • Large kidney stones
  • Hernia
  • Ovarian torsion
  • Ruptured spleen

Prevention

  • Stay hydrated to prevent kidney stones
  • Maintain good posture
  • Exercise regularly with proper form
  • Lift objects correctly
  • Maintain healthy weight
  • Eat high-fiber diet
  • Manage chronic conditions
  • Practice safe sex (prevent infections)
  • Don't ignore persistent pain
  • Regular medical check-ups

Frequently Asked Questions

What does pain on the left side vs the right side mean?

Location offers clues but is not a diagnosis. Right-sided pain more often involves the appendix (lower), the liver or gallbladder (upper), or the right kidney (toward the back). Left-sided pain more often involves the spleen (upper), the colon and diverticulitis (lower), or the left kidney. Kidney stones, muscle strain, gas, and shingles can affect either side.

When is side pain a medical emergency?

Seek emergency care for severe, sudden side pain, pain with a high fever and chills, blood in the urine, pain that comes in intense waves, pain after an injury, or pain with dizziness, fainting, or a rapid pulse. Right-lower side pain with nausea and fever can signal appendicitis, and side pain during pregnancy always needs prompt evaluation.

How do I know if side pain is a kidney stone or a pulled muscle?

Kidney stone pain is typically severe, comes in waves, may spread to the groin, and often comes with blood in the urine or nausea. Muscle strain usually hurts more with movement or touch, follows lifting or twisting, and eases with rest and heat. Persistent or severe pain should be checked by a clinician, since the two can feel similar.

Can gas or constipation cause side pain?

Yes. Trapped gas and constipation are common, harmless causes of cramping side pain, especially on the lower left where the colon sits. This type of pain often comes with bloating and eases after a bowel movement or passing gas. Pain that is severe, constant, or paired with fever or vomiting should be evaluated.