Kidney pain is also called renal pain. Your kidneys are on each side of the backbone, beneath the rib cage. The left kidney sits slightly higher than the right.

These bean-shaped organs filter waste out of your body as part of the urinary system. They also have many other important jobs. For example, your kidneys make a hormone that controls blood pressure.

Left kidney pain may feel like a sharp pain or dull ache on your left side or flank. You may have an upper backache, or the pain can spread to your stomach.

Kidney pain can happen for many reasons. Most kidney problems clear up with little or no treatment, but it’s important to watch for other symptoms and know when to see your doctor.

Left kidney pain may have nothing to do with the kidneys. Pain may be from nearby organs and tissue:

  • muscle pain
  • muscle or spine injury
  • nerve pain
  • joint pain or arthritis
  • rib injury
  • pancreas or gallbladder problems
  • digestive problems (stomach and intestines)

Let’s take a closer look at some of the potential causes of your pain. Many common conditions that cause kidney pain can affect just one kidney.

Not drinking enough water can cause pain in one or both kidneys. Water loss happens through sweating, vomiting, diarrhea, or too much urine. Conditions such as diabetes can also lead to dehydration.

Severe or chronic dehydration builds up wastes in your kidneys. Symptoms include:

  • pain or discomfort in the side or back
  • tiredness or fatigue
  • food cravings
  • difficulty concentrating

Treatment

Get plenty of water to stay hydrated. In addition to drinking more fluids, you can eat water-rich foods such as fresh fruit and vegetables. Drink extra water if you have coffee and other caffeinated drinks.

How much water you need depends on age, climate, diet, and other factors. Check the color of your urine to estimate whether you are hydrated. Dark yellow means you probably need more water.

Infections are a common cause of kidney pain. A urinary tract infection (UTI) happens in the bladder or urethra (the tube that carries urine from the bladder to the outside of the body). An infection can occur when unhealthy bacteria get into the body.

A UTI can spread to one or both kidneys. A kidney infection is also called pyelonephritis. Women — especially pregnant women — are at higher risk. This is because women have a shorter urethra.

If left kidney pain is due to an infection, you may have symptoms like:

  • back or side pain
  • stomach or groin pain
  • fever or chills
  • nausea or vomiting
  • frequent urination
  • pain or burning when urinating
  • cloudy or strong-smelling urine
  • blood or pus in the urine

Treatment

See your doctor right away if you have any of these symptoms. Treatment is very important for a kidney infection. You’ll likely need antibiotics. If left untreated, the infection can damage the kidneys.

Kidney stones are small, hard crystals that build up inside the kidneys. The most common ones are made of salts and minerals such as calcium. Kidney stones are also called renal lithiasis.

A kidney stone can cause pain when it moves or is passed out of the body through the urine. You may feel pain in the kidney and other areas. Symptoms include:

  • severe pain in the back and side
  • sharp pain in the stomach and groin
  • pain in one or both testicles (for men)
  • fever or chills
  • nausea or vomiting
  • pain when urinating
  • blood in the urine (pink, red, or brown color)
  • cloudy or strong-smelling urine
  • difficulty urinating

Treatment

Kidney stones can be very painful, but they’re usually not harmful. Most kidney stones need minor treatment with pain relief drugs. Drinking plenty of water helps to pass the stone. Medical treatment includes using sound waves to help break up the kidney stones.

A cyst is a round, fluid-filled sac. Simple kidney cysts happen when one or more cysts form in the kidneys. Simple cysts aren’t cancerous and don’t normally cause symptoms.

You may feel pain if a cyst grows too large. It can also cause problems if it gets infected or bursts. A kidney cyst can cause kidney pain and symptoms like:

  • fever
  • sharp or dull ache in the side or back
  • upper stomach (abdomen) pain

A large kidney cyst can cause a painful complication called hydronephrosis. This happens when the cyst blocks the flow of urine, making the kidney swollen.

Treatment

If you have a large cyst, your doctor may recommend a simple procedure to remove it. This involves using a long needle to drain it. It’s typically done under general or local numbing. Afterward, you’ll likely need to take a dose of antibiotics to prevent an infection.

Polycystic kidney disease (PKD) is when there are many cysts in one or both kidneys. This disease can be serious. The National Kidney Foundation notes that polycystic kidney disease is the fourth highest cause of kidney failure.

PKD can happen in adults of all races. Symptoms usually begin at the age of 30 years or older. This disease typically affects both kidneys, but you may feel pain on one side only. Signs and symptoms include:

  • side or back pain
  • frequent kidney infections
  • stomach swelling
  • high blood pressure
  • pounding or fluttering heart beat

High blood pressure is the most common sign of polycystic kidney disease. If left untreated, high blood pressure can worsen kidney damage.

Treatment

There’s no cure for PKD. Treatment includes controlling blood pressure with medications and diet. You may also need antibiotics for bladder or kidney infections. This helps prevent further damage to the kidney. Other treatment includes pain management and drinking plenty of water.

In serious cases, some people with PKD may need a kidney transplant.

One type of kidney inflammation is glomerulonephritis. It can be caused by other chronic conditions such as diabetes and lupus. Severe or long-term inflammation can trigger kidney damage.

Symptoms include pain in one or both kidneys, as well as:

  • pink or dark-colored urine
  • foamy urine
  • stomach, face, hands, and feet swelling
  • high blood pressure

Treatment

Treating kidney inflammation depends on the cause. For example, if you have diabetes, controlling blood sugar levels with medications and diet can help beat inflammation. If your kidneys are very inflamed, your doctor may also prescribe steroid drugs.

A blockage of blood to the kidney is called a renal infarction or a renal vein thrombosis. This happens when the blood supply to and from the kidney is suddenly slowed or stopped. There are several causes, including a blood clot.

Blood flow blockages to the kidney typically happens on one side. Symptoms include:

  • severe side or flank pain
  • lower back pain or ache
  • stomach (abdomen) tenderness
  • blood in the urine

Treatment

This serious condition can cause kidney damage. Treatment typically involves anticlotting drugs. The medication dissolves blood clots and prevents them from forming again.

Anticlotting drugs may be taken in tablet form or injected directly into the clot. In rare cases, surgery may be needed to remove a blood clot.

Bleeding or a hemorrhage is a serious cause of kidney pain. Disease, injury, or a blow to the kidney area can lead to bleeding inside the kidney. Signs and symptoms include:

  • side and low back pain
  • stomach pain and swelling
  • blood in urine
  • nausea and vomiting

Treatment

Pain relief and bed rest help to heal minor kidney bleeding. In serious cases, bleeding can lead to shock — causing low blood pressure, chills, and fast heart rate. Urgent treatment includes fluids to raise blood pressure. Surgery may be needed to stop a large kidney bleed.

Kidney cancer isn’t common in adults under the age of 64 years. In older adults some cancers can begin in the kidneys. Men are more likely to have kidney cancer. Renal cell carcinoma is a type of tumor that usually grows in one kidney only.

Kidney cancer typically has no symptoms in the early stages. Advanced symptoms include:

  • pain in the side or back
  • blood in the urine
  • loss of appetite
  • weight loss
  • fever
  • tiredness

Treatment

Like other types of cancer, kidney cancer is treated with chemotherapy drugs and radiation therapy. In some cases, surgery to remove a tumor or an entire kidney is needed.

Enlarged prostate

An enlarged prostate is a common condition in men over the age of 40. This gland is just below the bladder. As the prostate gland gets bigger, it can partially block urine flow out of the kidney. This can lead to infection or swelling in one or both kidneys, causing pain.

An enlarged prostate is usually treated with drugs to shrink it. In some cases, radiation therapy or surgery may be needed. Kidney symptoms clear up once the prostate is back to normal size.

Sickle cell anemia

Sickle cell anemia is a genetic condition that changes the shape of red blood cells. It can damage the kidneys and other organs. This leads to pain in the kidneys and blood in the urine.

Medications help to treat the effects of sickle cell anemia. Bone marrow transplants also help to relieve symptoms.

See your doctor if your left kidney pain is severe or doesn’t go away. Seek medical attention if have any other symptoms. Warning signs of a kidney condition include:

  • fever
  • pain or burning when urinating
  • having to urinate often
  • blood in the urine
  • nausea and vomiting

Your doctor may recommend scans and tests to find out the cause of your left kidney pain:

  • blood test
  • urine test
  • ultrasound
  • CT scan
  • MRI scan
  • genetic test (usually a blood test)

Most causes of kidney pain can be treated and don’t cause kidney damage or complications. However, it’s important to get treatment as early as possible.

Kidney self-care is good for your overall health. These include:

  • not smoking
  • eating a balanced, low-salt daily diet
  • exercising regularly
  • drinking plenty of water