What Is Kidney Pain?
Kidney pain is discomfort that comes from the area where your kidneys are. It's often described as a dull ache that you feel in your sides, back, or belly. But pain in these areas isn't always a sign of a kidney issue. It's easy to mistake kidney pain for ordinary back pain, but there are some differences in how they feel and where they're located.
Kidney pain has many possible causes, and some could be serious. It's important to let your doctor know if you notice pain that you think may be coming from one or both of these organs.
Where are your kidneys?
Your kidneys are two small organs shaped like beans. You have one on each side of your body. They're each about the size of your fist.
Your kidneys have important jobs. They clean out water, acids, and waste from your blood. They make urine so your body flushes out the waste. If they're diseased or damaged in some way, they can't do their work to maintain a healthy balance of salts, minerals like calcium, and water in your blood.
Your kidneys also make hormones that help you manage your blood pressure, keep your bones strong, and make red blood cells.
So, it's important to watch for any signs of kidney disease or damage, such as pain.
Kidney pain location
Your two kidneys sit just below your ribcage on either side of your spinal cord. Often, you'll feel kidney pain on the left or right side of your back under your ribs. The pain may spread to your belly or groin area.
Kidney Pain Symptoms
Kidney pain symptoms include:
- A dull ache that's usually constant
- Pain under your rib cage or in your belly
- Pain in your side; usually only one side, but sometimes both hurt
- Sharp or severe pain that may come in waves
- Pain that can spread to your groin area or belly
Other symptoms that can happen with kidney pain
The symptoms of your kidney pain depend on its cause. With kidney pain, you may also have:
- Fever
- Vomiting
- Pain when you pee
- Cloudy urine
- Blood in your urine
Kidney Pain Causes
Kidney pain has many possible causes. Your kidneys are connected to other organs, such as your bladder and ureters, where you store and get rid of urine.
Intense, sudden, stabbing pain may indicate a kidney stone. These are mineral deposits that can grow large enough to block a ureter, a tube that connects your kidney and bladder. If that happens, you'll feel sharp pain or cramps in your back or side. It can also spread out to your groin. As you try to pee out the stone, you might feel waves of pain.
Kidney infection pain
Also called pyelonephritis, this infection could cause discomfort in one or both kidneys. You may feel pain in your back, in your side or both sides under your ribs, or in your groin. You'll also have a fever. Urinary tract infections also cause discomfort in this organ.
Dehydration kidney pain
Your kidneys need water to remove wastes via your urine. Fluid also helps nutrients travel through your bloodstream to your kidneys. When you don't drink enough fluid or lose too much through sweat or vomit, wastes can build up in your kidneys. Dehydration also makes you more likely to form kidney stones. Drinking extra fluids, especially if it's hot out and when you exercise, can help prevent dehydration.
COVID-19 kidney pain
Coronavirus can damage the kidneys. More than 30% of people who are hospitalized with COVID-19 have kidney damage. The virus may harm the kidneys in a few ways. Sometimes, it directly infects kidney cells. Or it can cause clots that block the flow of blood to the kidneys. Lung damage from COVID-19 can reduce the oxygen these organs need to work.
Other causes of kidney pain
Urinary retention. When you can't fully empty your bladder, urine backs up into your kidneys. Your kidneys swell up from the extra urine and press on nearby organs. That pressure can damage your kidneys and cause severe pain in your lower belly.
- Vesicoureteral reflux (VUR). In VUR, urine flows backward up the ureters—the tubes that carry urine from your kidneys to your bladder. You may have pain in your side and when you pee. The backward flow of urine into the kidneys can cause urinary tract infections. If VUR isn't treated, it can damage the kidneys.
Ureteral stricture. Stricture is a narrowing in the ureters that blocks the flow of urine from one or both kidneys to the bladder. Scar tissue from an injury or surgery, kidney stones, and kidney cancer can cause ureteral stricture. The narrowing backs up urine into the kidney, which may be painful—especially when you pee.
- Ureteropelvic junction obstruction. This is a blockage in the spot where your ureter attaches to your kidney. It slows the flow of urine down the ureter, which increases pressure in the kidney and makes it swell up. You'll feel the pain on the side with the blocked ureter in the area between your ribs and hip. The pain might spread to your belly or groin.
Kidney swelling. This condition, called hydronephrosis, can happen if your kidneys are blocked. Your urine can't drain the way it should and builds up in your kidneys. This can happen in one or both kidneys and sometimes it causes pain.
Kidney cysts. You may not feel a simple kidney cyst until it grows larger. Once it gets big, you might feel a dull pain in your side or back, or pain in the upper part of your belly.
Polycystic kidney disease. This genetic disease causes many cysts to grow in your kidneys. They may cause you to feel pain in your back or side.
Kidney cancer. Tumors in your kidney may not cause any discomfort early on. As the cancer gets worse, you may notice pain in your side, back, or belly that doesn't come and go or get less intense.
Benign kidney tumor or mass. A renal mass is a noncancerous tumor or growth. It feels like pain in your flank, between your ribs and your hips on your side. You'll also have low back pain on one side of your body that lingers.
Renal vein thrombosis. A blood clot can form in one of the veins in your kidney. It causes severe, ongoing pain in your flank or side. You may feel spasms of pain at times. The area around the affected kidney between your rib cage and spine could feel sore.
Kidney injury. Many contact sports or vigorous activities such as football, boxing, horseback riding, or soccer could put you at risk for a kidney injury. If this happens, the discomfort might be on either side of your belly or in your lower back. It could range from mild to very strong, depending on how badly you're injured.
Kidney Pain vs. Back Pain
It's easy to confuse kidney pain with just back pain. How do you know the difference?
Location. It could be your kidney and not your back if you feel it higher on your back. Back problems usually affect your lower back.
Kidney pain is felt higher and deeper in your body than back pain. You may feel it in the upper half of your back, not the lower part. Unlike back discomfort, it's felt on one or both sides, usually under your rib cage.
It's often constant. Kidney pain probably won't go away when you shift your body. However, back pain might lessen when you adjust your position.
Signs that it's your back
Back pain:
- Shoots down one leg
- Is more likely to be stabbing than dull and constant
- Gets worse or flares up when you do certain activities, like lifting a box or bending over
- When you rest or lie down, back pain may ease up
- Might also be muscle aches
Other symptoms to watch for
Depending on the cause of the pain, you could have other symptoms too. If you have these signs, contact your doctor as you could have a serious kidney problem:
- Fever
- Body aches
- Tiredness
Also, if you recently had a urinary tract infection (UTI), call your doctor. If you have blood in your urine, or if your pain is sudden and unbearable even without signs of blood in your pee, get medical care right away.
Kidney Pain Diagnosis
For kidney pain, you may start with a visit to your primary care doctor or a nephrologist—a doctor who diagnoses and treats kidney diseases. The doctor will ask about your symptoms and examine you.
Kidney pain tests
A few tests can help your doctor find the cause of your kidney pain:
- Blood test. This test checks for signs of infection or kidney stones. It also can show how well your kidneys are filtering wastes from your blood.
- Urine tests. These tests check for infections, proteins, and other substances in your urine from kidney diseases.
- Ultrasound. This imaging test uses sound waves to make pictures of your kidneys and other parts of your urinary tract.
- Computed tomography. This scan takes detailed pictures of your kidneys from different angles.
- Magnetic resonance imaging (MRI). This test uses a strong magnet, radio waves, and a computer to make detailed pictures of your kidneys.
When to See a Doctor
Call your doctor if kidney pain is constant or it doesn't go away. Also, see a doctor for symptoms such as:
- Fever or chills
- Blood in your pee
- Pain when you pee
- A change in your urine color
- A constant urge to pee
- Body aches
- Tiredness
- Nausea or vomiting
Kidney Pain Treatment
Once your doctor diagnoses the cause of your kidney pain, they can decide on the best treatment plan for you. Treatment plans will vary depending on the cause.
Your doctor will likely prescribe you an antibiotic if your kidney pain is being caused by an infection.
If your pain stems from kidney stones, your doctor may prescribe you medication to help you pass the stone. But if you have many kidney stones, or they're too big to pass, your doctor may recommend surgery to break them down.
You should always discuss your kidney pain symptoms with your doctor as soon as possible, but while you're waiting for treatment, you can take the following steps to help ease kidney pain at home:
- Use a heating pad on your back or abdomen.
- Drink plenty of water. This may help flush bacteria from your urinary tract. Avoid alcohol or beverages with lots of caffeine.
- Ask your doctor before you take any pain relievers.
Takeaways
Kidney pain has many possible causes, including an infection, an injury, or kidney stones. You'll feel pain from a kidney problem in your back on the left or right side of your spine. Blood and urine tests, and sometimes imaging tests, can help your doctor find the source of the pain. Once your doctor knows the cause, they can find the right treatment for you.
Talk to your doctor about any kidney pain that does not go away or comes with symptoms such as fever, blood in your pee, or pain when you pee.
Kidney Pain FAQs
What are the signs of your kidneys hurting?
Along with pain in your side or upper back, you may have fever, chills, and vomiting. It might hurt when you pee. Your urine can look cloudy or bloody.
What should I do if my kidney is hurting?
See your primary care doctor. The doctor might refer you to a kidney specialist called a nephrologist for tests.
When should I be worried about kidney pain?
Constant kidney pain that doesn't go away is worth talking to your doctor about. Fever, body aches, tiredness, and pain or blood when you pee are other symptoms to seek immediate medical attention for.