If you’re experiencing what feels like kidney pain, the most important first step is figuring out whether it’s actually coming from your kidneys or from your lower back muscles. True kidney pain sits in your flank, the area on either side of your spine just below your rib cage and above your hips. Unlike back pain, it doesn’t get better or worse when you shift positions. Once you’ve identified it as likely kidney-related, your next move depends on how severe it is and what other symptoms you have.
How to Tell It’s Your Kidneys, Not Your Back
Kidney pain and lower back pain overlap in location, which makes them easy to confuse. But they behave differently. Kidney pain stays constant regardless of how you move. It doesn’t improve when you stretch, lie down, or change positions. It also doesn’t go away on its own without treatment. The pain often stays in one spot but can spread down into your lower abdomen or inner thighs.
Back pain, by contrast, tends to feel like a dull ache, stiffness, or soreness that shifts with movement. Certain motions make it worse, and finding a comfortable position usually brings some relief. If nerves are involved, back pain often radiates down one or both legs. Kidney pain doesn’t do that. If your pain is deep, one-sided, sits right below your ribs, and nothing you do with your body changes it, your kidneys are the more likely source.
Common Causes of Kidney Pain
The two most frequent culprits are kidney stones and kidney infections. Kidney stones cause pain when they move from the kidney into the narrow tube (ureter) that connects to your bladder. This can produce sudden, intense, wave-like pain that many people describe as the worst they’ve ever experienced. The pain often comes and goes in cycles as the ureter contracts around the stone.
Kidney infections, known as pyelonephritis, typically start as a urinary tract infection that travels upward. The pain is usually steady rather than wave-like, and it’s almost always accompanied by fever, chills, nausea, or pain during urination. Less common causes include blood clots in the kidney’s blood vessels, cysts, and trauma to the area.
When to Go to the Emergency Room
Some kidney pain warrants an ER visit rather than waiting for a doctor’s appointment. Go in if your pain is persistent and you also have any of the following:
- Fever or chills: this suggests infection, which can become dangerous quickly if it spreads to your bloodstream
- Blood in your urine: visible pink, red, or brown urine points to stones, infection, or other conditions that need prompt evaluation
- Inability to urinate: a blocked ureter can cause urine to back up into the kidney, which requires urgent treatment to prevent damage
Severe nausea and vomiting alongside kidney pain also merit urgent care, partly because dehydration makes most kidney problems worse and partly because these symptoms can signal a stone that needs intervention.
What You Can Do at Home
For mild to moderate kidney pain while you’re waiting to see a provider, hydration is the single most helpful thing you can do. Drinking plenty of water helps flush your urinary tract and, in the case of small stones, may help move them along. Aim for enough water that your urine stays pale yellow or clear.
For pain relief, be cautious with over-the-counter medications. NSAIDs like ibuprofen and naproxen are effective for kidney stone pain in the short term, but long-term or frequent use of these drugs can actually damage your kidneys. The same is true for acetaminophen. Using any of these pain relievers regularly over weeks or months has been linked to a condition called analgesic nephropathy, which involves structural damage inside the kidney. For a day or two while you arrange to see a doctor, short-term use is generally reasonable, but these are not a long-term solution for recurring kidney pain.
A heating pad placed on your flank can also help ease discomfort. Avoid alcohol, which is dehydrating and adds stress to your kidneys.
What Happens at the Doctor’s Office
Your provider will likely start with a urine test. This checks for blood cells (present in about 85% of people with kidney stones), signs of infection, and other abnormalities. A basic blood test measuring your creatinine level tells your doctor how well your kidneys are filtering waste. From that value, they calculate something called your eGFR, a score that rates your kidney function. An eGFR of 90 or higher is normal. Scores between 60 and 89 may indicate early-stage kidney disease, and anything below 60 signals more significant problems.
For imaging, ultrasound is typically the first step. It’s radiation-free and can detect swelling in the kidney caused by a blockage, as well as larger stones. If the ultrasound doesn’t provide a clear answer and your doctor still suspects a stone, a CT scan without contrast dye is the gold standard. It picks up stones of nearly any size and location. Pregnant women and children are generally evaluated with ultrasound only, to avoid radiation exposure.
Treatment and Recovery Timelines
What happens next depends entirely on the cause. Small kidney stones (under about 5 millimeters) often pass on their own with hydration and pain management over a few days to a couple of weeks. Larger stones may need a procedure to break them up or remove them.
Kidney infections require antibiotics. Most people start feeling noticeably better within two to three days of starting treatment, though it can take longer in some cases. You’ll typically need to finish a full course of antibiotics even after symptoms improve. Severe infections, especially those accompanied by high fever, confusion, or an inability to keep fluids down, sometimes require a short hospital stay for IV treatment.
If your pain turns out to be related to a chronic condition like cysts or early kidney disease, your doctor will focus on protecting your remaining kidney function. This usually involves managing blood pressure, adjusting your diet (particularly protein and sodium intake), and monitoring your kidney function with periodic blood tests.
Preventing Recurrence
If you’ve had a kidney stone, your chance of getting another one within five years is significant. Staying well-hydrated every day is the single most effective preventive measure. Reducing sodium intake also helps, because excess salt increases the amount of calcium your kidneys need to filter, which promotes stone formation. Depending on the type of stone you had, your doctor may recommend specific dietary changes, like eating less animal protein or limiting foods high in oxalates (spinach, nuts, chocolate).
For kidney infections, the key is catching and treating urinary tract infections early before they have a chance to travel upward. Urinating after sex, staying hydrated, and not holding your urine for long periods all reduce UTI risk. If you get recurrent infections, your provider may investigate whether there’s a structural issue in your urinary tract that’s making you more susceptible.