If your kidneys hurt, the first steps are to stay hydrated, apply heat to the area, and use acetaminophen (not ibuprofen) for pain relief. Most kidney pain comes from either a kidney stone trying to pass, an infection working its way through the urinary tract, or inflammation from dehydration. What you do next depends on how severe the pain is and whether you have other symptoms alongside it.
Make Sure It’s Actually Your Kidneys
Kidney pain and back pain feel different, but the location overlaps enough to cause confusion. Your kidneys sit against the back muscles just below the rib cage, so kidney pain shows up in the flank, the area on either side of your spine between the bottom of your ribs and the top of your hips. It often stays in one spot but can spread to the lower abdomen or inner thighs.
The key difference is movement. Muscular back pain tends to worsen when you twist, bend, or shift position, and it often eases when you find a comfortable posture. Kidney pain does not change with movement. It stays constant regardless of how you sit or stand, and it generally does not improve on its own without some kind of treatment. If you’re experiencing a dull ache or stiffness that shifts when you reposition, you’re more likely dealing with a muscle issue. If the pain is deep, steady, and unaffected by how you move, your kidneys are more likely the source.
What You Can Do Right Now
Drink plenty of water. This is the single most useful thing you can do for nearly every type of kidney pain. Water helps flush bacteria if you have an infection and keeps stone-forming crystals from clumping together. There’s no universal magic number for how much to drink. Your needs depend on your age, body size, climate, and activity level. But if you’re in pain and your urine looks dark, you’re almost certainly not drinking enough. Aim for pale yellow urine as a practical target.
For pain relief, place a heating pad on low over your lower belly or take a hot shower. If you use a heating pad, put a thin cloth between it and your skin, and never fall asleep with it on. Over-the-counter acetaminophen (Tylenol) is generally safe for kidney-related pain. Avoid ibuprofen, naproxen, and other anti-inflammatory painkillers in the NSAID family. These reduce blood flow to the kidneys and can cause acute kidney injury, especially at higher doses or with repeated use.
Symptoms That Need Urgent Attention
Some combinations of symptoms mean this isn’t something to manage at home. Get to a doctor or emergency room if your kidney pain comes with any of the following:
- Fever or chills, which suggest infection has taken hold
- Blood in your urine
- Inability to urinate
- Severe nausea or vomiting, especially if you can’t keep fluids down
- Pain when urinating
- A repeated, urgent need to pee that’s unusual for you
- Pain that you simply cannot manage with over-the-counter options
- Persistent fatigue or a general feeling of illness that won’t lift
Any of these alongside flank pain points toward a kidney infection, a stone that’s stuck, or another condition that needs medical evaluation quickly.
If It’s a Kidney Stone
Kidney stones cause some of the most intense pain people experience, often coming in waves as the stone moves through the ureter (the tube connecting each kidney to the bladder). Whether you can pass a stone at home depends almost entirely on its size.
Stones smaller than 2 mm pass on their own about 85% to 90% of the time with just water and pain relief. Stones between 2 and 4 mm still pass naturally about 80% of the time, sometimes with the help of medication to relax the ureter. At 4 to 6 mm, the odds drop to roughly 60% to 70%. Once a stone reaches 6 to 7 mm, fewer than half pass without a procedure. Stones larger than 10 mm almost always require some form of surgical removal.
If you’ve passed a stone before and recognize the pain, drinking extra water and managing pain with acetaminophen and heat may be enough for a small stone. But if you don’t know the stone’s size, or if the pain is escalating, a doctor can use an ultrasound or CT scan to measure it and decide whether you need intervention or can safely wait.
Dietary Changes That Help
If kidney stones are a recurring problem, what you eat matters. Sodium is one of the biggest dietary drivers of stone formation. Processed and fast foods, canned soups and vegetables, lunch meats, and many condiments are loaded with it. Cutting back on packaged food is one of the most effective changes you can make.
For calcium oxalate stones, the most common type, certain high-oxalate foods contribute to crystal formation. The biggest culprits are spinach, nuts and nut products, peanuts, rhubarb, and wheat bran. You don’t necessarily need to eliminate these entirely, but reducing them can lower the concentration of oxalate in your urine and make stones less likely to form.
If It’s a Kidney Infection
Kidney infections usually start as a bladder infection that climbs upward. The pain is typically on one side, deep in the flank, and accompanied by fever, chills, nausea, or burning during urination. Unlike kidney stones, which cause intermittent waves of sharp pain, infection pain tends to be more constant and is often paired with feeling genuinely sick.
Kidney infections require antibiotics, typically for at least 14 days. A doctor will test your urine for signs of infection and may order blood work or imaging to check for complications like a blockage. Drinking plenty of water alongside the antibiotics helps flush bacteria from the urinary tract. If you have a known kidney, heart, or liver condition that requires you to limit fluids, check with your doctor before increasing your water intake.
Untreated kidney infections can become serious quickly. If you suspect an infection rather than a stone, don’t wait to see if it resolves on its own.
What to Expect at the Doctor
When you go in for kidney pain, the evaluation typically starts with a urine test to look for blood, bacteria, or crystals. Blood tests can show whether your kidneys are filtering properly. If your provider suspects a stone or structural problem, they’ll likely order an ultrasound, which can reveal blockages, stones, or swelling in the kidneys. A CT scan provides more detail when needed.
Expect questions about when the pain started, how severe it is, how much you drink daily, what medications you take (including over-the-counter ones), and whether you’ve had kidney problems before. Your caffeine and alcohol intake may come up too, since both affect hydration and kidney workload. If you’re female, they’ll ask whether you could be pregnant, since that changes which imaging and treatments are safe.
Protecting Your Kidneys Going Forward
Staying well-hydrated is the most consistent piece of kidney protection across nearly every condition. Water dilutes the substances that form stones, helps flush bacteria before infections take root, and supports the kidneys’ basic filtering work. If you’ve had a stone or infection before, your risk of another one is higher, and consistent hydration becomes even more important.
Be cautious with pain medications long-term. NSAIDs like ibuprofen and naproxen reduce blood flow to the kidneys, and repeated use can cause lasting damage. People with any degree of reduced kidney function should avoid them. Acetaminophen is the safer choice for kidney-related pain, though it’s harder on the liver, so people with liver disease should check on safe dosing. Keeping your sodium intake in check, drinking water throughout the day rather than in bursts, and paying attention to recurring flank pain before it becomes severe are the practical habits that keep most kidney problems from escalating.