Is It Kidney Pain? Why Your Flank Hurts & Medically Approved Next Steps

If you're feeling pain in your side or lower back, it's natural to wonder: Is this kidney pain?

Flank pain—the discomfort felt on either side of your spine, just below your rib cage—can have many causes. Some are minor and temporary. Others need prompt medical care. Understanding what kidney pain feels like, how it differs from muscle or back pain, and what to do next can help you make informed decisions without unnecessary panic.

Let's break it down clearly and calmly.

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Where Is Kidney Pain Felt?

Your kidneys sit in your upper abdomen, toward your back, just under your lower ribs—one on each side of your spine.

Kidney pain is typically felt:

• In the flank (side of your back)
• Just below the rib cage
• Sometimes radiating to the lower abdomen or groin
• Usually deeper and harder to pinpoint than muscle pain

It may affect one side or both, depending on the cause.

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What Does Kidney Pain Feel Like?

People describe kidney pain in different ways depending on the underlying issue.

Common descriptions include:

• A deep, dull ache in the side or back
• Sharp or severe cramping pain
• Pain that comes in waves
• Pain that doesn't improve with movement or position changes

If the pain is from kidney stones, it's often:

• Sudden and severe
• Cramping in nature
• Radiating toward the groin
• Associated with nausea or vomiting

If it's from a kidney infection, you may also experience:

• Fever
• Chills
• Burning during urination
• Frequent urge to urinate
• Cloudy or foul-smelling urine

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Kidney Pain vs. Muscle or Back Pain

Not all flank pain is kidney pain. In fact, muscle strain is much more common.

Here's how they typically differ:

Muscle or Back Pain

• Often linked to movement or lifting
• Improves with rest
• Worse with certain positions
• Tender when you press on the area

Kidney Pain

• Feels deeper
• Not affected much by movement
• May come with urinary symptoms
• May be accompanied by fever or nausea

If you recently lifted something heavy or strained your back, a muscle cause is more likely. If you have urinary symptoms or fever, kidney-related causes move higher on the list.

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Common Causes of Kidney Pain

1. Kidney Stones (Nephrolithiasis)

Kidney stones are hard mineral deposits that form in the kidneys. When they move into the urinary tract, they can cause intense pain.

Symptoms may include:

• Severe flank pain
• Pain radiating to the groin
• Blood in urine
• Nausea or vomiting
• Urgency to urinate

If these symptoms sound familiar, you can use a free symptom checker for Nephrolithiasis (Kidney Stones) to help identify whether your symptoms align with kidney stones and get guidance on next steps.

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2. Kidney Infection (Pyelonephritis)

A kidney infection usually begins as a urinary tract infection (UTI) that spreads upward.

Warning signs include:

• Fever over 100.4°F (38°C)
• Chills
• Flank pain
• Painful urination
• Fatigue
• Nausea

Kidney infections require antibiotics. Without treatment, they can become serious.

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3. Urinary Tract Infection (Lower UTI)

A bladder infection may cause discomfort lower in the abdomen but can sometimes feel like flank discomfort.

Common symptoms:

• Burning with urination
• Frequent urination
• Urgency
• Cloudy urine

Lower UTIs typically don't cause severe flank pain unless the infection spreads.

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4. Blockage or Swelling (Hydronephrosis)

If urine flow is blocked—by a stone, enlarged prostate, or other obstruction—pressure can build in the kidney.

This may cause:

• Flank pain
• Decreased urination
• Nausea
• Visible swelling in severe cases

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5. Less Common Causes

Less frequently, kidney pain may be related to:

• Kidney cysts
• Kidney trauma
• Blood clots in the kidney
• Tumors

These are less common but should be evaluated if symptoms persist or worsen.

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When Is Kidney Pain an Emergency?

Some symptoms require immediate medical attention.

Seek urgent care or go to the emergency room if you have:

• Severe, unrelenting pain
• Fever with flank pain
• Vomiting that prevents fluid intake
• Blood in your urine
• Confusion or weakness
• Decreased urination
• Known kidney disease with new pain

These could indicate a serious infection, obstruction, or other complication.

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What Can You Do Right Now?

If your pain is mild and you feel otherwise well:

• Stay hydrated (unless your doctor has told you to restrict fluids)
• Rest
• Monitor your temperature
• Track urinary symptoms
• Avoid heavy lifting

Do not ignore persistent or worsening kidney pain. Early evaluation can prevent complications.

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How Doctors Diagnose Kidney Pain

If you speak to a healthcare provider, they may recommend:

• A physical exam
• Urine test (to check for infection or blood)
• Blood tests (to assess kidney function)
• Imaging tests such as ultrasound or CT scan

These tools help determine whether your kidney pain is due to stones, infection, obstruction, or something else.

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Risk Factors for Kidney Problems

Certain factors increase your risk of kidney pain from stones or infection:

• Dehydration
• High-sodium diet
• Family history of kidney stones
• Recurrent UTIs
• Diabetes
• Weakened immune system
• Pregnancy

If you fall into one of these categories, take flank pain more seriously.

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Preventing Kidney Pain

While not all causes are preventable, you can reduce risk by:

• Drinking adequate fluids daily
• Limiting excess salt
• Managing blood sugar if diabetic
• Treating UTIs promptly
• Maintaining a healthy weight

Prevention isn't perfect, but it helps.

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The Bottom Line: Is It Kidney Pain?

Flank pain does not automatically mean kidney pain. Many cases are muscular and improve on their own.

However, kidney pain often:

• Feels deep and steady or severely cramping
• Comes with urinary symptoms
• May involve fever or nausea
• Does not improve with simple position changes

If you're unsure, using a structured tool like a symptom checker can help clarify possibilities. And if symptoms are concerning or worsening, do not wait.

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When to Speak to a Doctor

You should speak to a doctor if:

• Pain lasts more than a day or two
• You have fever or chills
• Urination is painful or abnormal
• You see blood in your urine
• Pain is severe
• You have a history of kidney disease or stones

Some causes of kidney pain can become life-threatening if untreated, particularly kidney infections and urinary blockages. Prompt evaluation can make a major difference.

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Final Thoughts

Kidney pain is your body's signal that something may be wrong in the urinary system. Sometimes it's temporary. Sometimes it needs medical treatment. The key is paying attention to accompanying symptoms and acting appropriately.

Stay calm, stay observant, and don't ignore red flags. If anything feels severe, unusual, or worrisome, speak to a doctor immediately. Your kidneys play a vital role in your health—and when they send a signal, it's worth listening.