How to Relieve Flank Pain: At-Home and Medical Options

Flank pain, the aching or sharp discomfort between your lower ribs and hip on one or both sides of the back, usually responds well to a combination of at-home strategies and, when needed, targeted medical treatment. The right approach depends almost entirely on what is causing the pain. A kidney stone, a urinary tract infection, a pulled muscle, and even shingles can all produce pain in the same general area but call for very different remedies. What follows covers the most effective options for each scenario, from what you can do tonight to what a urologist or emergency physician might recommend.

Why the Cause Matters Before You Treat

Flank pain is a symptom, not a diagnosis. The most common culprits are kidney stones, kidney infections (pyelonephritis), and musculoskeletal strains of the back or abdominal wall muscles. Less common but important causes include shingles, ovarian cysts, and, rarely, an abdominal aortic aneurysm, which can present as flank pain along with abdominal pain and signs of poor blood flow to the legs.¹ Figuring out the underlying problem, even roughly, helps you choose home remedies that actually work and tells you whether you need to see a doctor today or can safely wait.

Over-the-Counter Pain Medication

For most causes of flank pain, an over-the-counter nonsteroidal anti-inflammatory drug (NSAID) like ibuprofen or naproxen is the single most effective first step. This is especially true for kidney stone pain, where NSAIDs have been studied head-to-head against opioid painkillers in dozens of trials. A systematic review pooling data from multiple randomized trials found that patients given NSAIDs achieved greater reductions in pain scores than those given opioids, needed less rescue medication, and had far less vomiting.² A later meta-analysis confirmed the pattern: NSAIDs showed a small but real edge over opioids in initial pain reduction at 30 minutes, required fewer rescue treatments, and caused less nausea.³

NSAIDs also reduce inflammation in strained muscles and irritated soft tissue, making them a reasonable go-to for musculoskeletal flank pain as well. Acetaminophen (paracetamol) is an alternative if you can’t tolerate NSAIDs, though the evidence for kidney stone pain specifically is weaker. If you have kidney disease, a bleeding disorder, or stomach ulcer history, check with a pharmacist or doctor before using any NSAID.

Heat and Cold Therapy

Applying heat or cold to the painful area is one of those remedies people swear by, and the research broadly supports it as a modest add-on to medication. A randomized trial testing heating pads and cold packs alongside ibuprofen for acute back and neck strain found that both heat and cold produced similar mild improvements in pain, though the researchers noted the improvement could have been driven mainly by the ibuprofen itself.⁴ In other words, heat or cold probably helps, but it is the painkiller doing the heavy lifting.

When comparing the two directly for low-back soreness, heat tends to come out slightly ahead. In one controlled trial, a continuous low-level heat wrap reduced pain by roughly 138% more than a cold pack in the early phase of muscle soreness.⁵ For musculoskeletal flank pain specifically, heat is usually the better choice: it increases blood flow and relaxes tight muscles. Cold works better for acute swelling or bruising. If you are dealing with kidney stone colic, a heating pad held against your flank or lower back can make the cramping waves more bearable while you wait for medication to kick in.

Staying Hydrated

If your flank pain is related to a kidney stone or a urinary tract infection, drinking plenty of fluids is both treatment and prevention rolled into one. Keeping urine dilute helps smaller stones move through the ureter and flushes bacteria out of the urinary tract. Expert guidelines recommend a daily fluid intake of about 2.5 to 3 liters for people prone to kidney stones, aiming for urine output of roughly 2 to 2.5 liters a day.⁶ A systematic review of fluid intake studies confirmed that higher fluid consumption was associated with increased urine output and reduced stone formation.⁷

Water is the go-to choice. Interestingly, a large population-based study found that tea, coffee, and alcohol were each associated with lower stone risk per additional serving, while plain water intake in that cohort did not show the same protective association, possibly because water intake was harder to measure accurately in the dataset.⁸ That does not mean water is useless; it simply means that total fluid volume matters more than the specific beverage. If your flank pain is muscular rather than kidney-related, extra hydration is still a good idea but won’t be the main remedy.

When a Kidney Stone Needs Medical Expulsion Therapy

Most kidney stones under about 5 to 6 mm will pass on their own with fluids and pain control. Larger stones, or ones that stall in the ureter, sometimes benefit from a class of medications called alpha-blockers, with tamsulosin being the most studied. A large meta-analysis of 46 studies found that tamsulosin improved the overall stone expulsion rate compared with no medication, from about 70% to about 80%.⁹ The benefit was clearest for stones larger than 6 mm; for smaller stones, the expulsion rate was similar whether or not tamsulosin was used. A smaller trial also found that tamsulosin reduced the number of pain episodes and the total amount of painkillers needed during the waiting period.¹⁰

The picture is not perfectly clear-cut, though. A large placebo-controlled trial known as SUSPEND found no difference in spontaneous stone passage between patients given tamsulosin, nifedipine (a calcium channel blocker), or placebo, and concluded that medical expulsion therapy was unlikely to be cost-effective.¹¹ The discrepancy likely comes down to study design differences and stone sizes enrolled. In practice, many urologists still prescribe tamsulosin for stones in the 5 to 10 mm range on the grounds that the drug is inexpensive, well tolerated, and may shorten the wait.

Procedures for Stones That Will Not Pass

When a stone is too large to pass or causes complications like infection or persistent blockage, two main procedures are used: shockwave lithotripsy (SWL), which breaks stones apart with focused sound waves from outside the body, and ureteroscopy (URS), where a thin scope is threaded up through the urinary tract to grab or laser the stone directly.

SWL is less invasive and cheaper, but it comes with a higher chance of needing a follow-up procedure. A large comparative study of nearly 48,000 patients found that after adjusting for patient differences, the probability of needing a repeat intervention was about 11% after SWL compared with less than 1% after ureteroscopy.¹² A randomized trial comparing the two specifically for ureteral stones found a similar pattern: about 22% of the SWL group needed further treatment versus about 10% in the ureteroscopy group, though SWL cost less overall.¹³

For small stones in the lower part of the kidney (10 mm or less), a recent randomized trial found no difference in overall health outcomes between the two methods, although ureteroscopy produced higher stone-free rates while shockwave lithotripsy was more cost-effective.¹⁴ The decision between the two usually comes down to stone size, location, your anatomy, and how much you want to minimize the odds of a second procedure.

Treating a Kidney Infection

If your flank pain comes with fever, chills, nausea, or burning during urination, the cause may be pyelonephritis, a kidney infection that needs antibiotics. This is not something to manage with home remedies alone. The good news is that most uncomplicated cases respond well to oral antibiotics, without needing an IV in the hospital. A Cochrane review of 57 randomized trials involving over 12,000 adults found that oral antibiotics were as effective as starting with IV antibiotics and then switching to oral for both short-term and long-term cure rates.¹⁵ Shorter courses of fluoroquinolones (seven days or less) also performed as well as longer courses in that review. Your doctor will choose the antibiotic based on local resistance patterns and your urine culture.

Musculoskeletal Flank Pain

Not all flank pain comes from the kidneys. The muscles of the back and abdominal wall, particularly the quadratus lumborum, a deep muscle connecting the lowest rib to the pelvis, are a frequent source of pain in this region. Repetitive motion, poor posture, or a sudden twist can produce trigger points in these muscles that refer pain into the flank and sometimes down into the hip. Myofascial pain of this type is best treated with a combination of approaches including physical therapy, postural correction, and sometimes trigger point injections with a local anesthetic.¹⁶

A case report on lower thoracic syndrome documented how manual therapy and therapeutic exercise targeting the T11-T12 region and pelvis reduced both local tenderness and radiating flank pain over eight treatment sessions.¹⁷ Core stabilization exercises can also help. A randomized trial in women with low back pain found that lumbar stabilization exercises combined with breathing resistance training produced significant improvements in pain and disability scores.¹⁸ If your flank pain worsens with twisting, bending, or pressing on the muscles and does not come with urinary symptoms or fever, a musculoskeletal cause is worth investigating before assuming a kidney problem.

Shingles and Nerve-Related Flank Pain

Shingles (herpes zoster) is an underappreciated cause of flank pain. The virus reactivates along a single nerve root, producing a band of burning pain that wraps around one side of the torso, often before any rash appears. In some cases, the pain occurs without a rash at all, a presentation called zoster sine herpete. A study comparing patients with rash-free zoster to those with the typical rash found that the rash-free group actually experienced more severe pain and used significantly more opioid medication.¹⁹ This makes nerve-related flank pain easy to misdiagnose as a kidney or muscle problem.

Antiviral medication started within 72 hours of symptom onset can shorten the episode and reduce the risk of lingering nerve pain (postherpetic neuralgia). For pain that persists after the acute episode, treatments include tricyclic antidepressants like nortriptyline, the anticonvulsant gabapentin, and topical lidocaine patches.²⁰

What Tests to Expect

When you see a doctor for flank pain, they will usually start with a urine test. Finding blood in the urine raises suspicion for a kidney stone, but its absence does not rule one out. A study specifically examining hematuria in patients with acute flank pain concluded that the absence of blood in the urine cannot exclude ureterolithiasis, and even when blood is strongly present, the positive predictive value is not high enough to confirm the diagnosis without imaging.²¹

Imaging typically comes next. CT scan is the gold standard for detecting kidney stones and can identify other causes of flank pain like appendicitis or an aortic aneurysm. Ultrasound is often used first because it avoids radiation, but it is less precise. A study comparing ultrasound to CT for stone surveillance found that ultrasound had a sensitivity of about 77% and tended to overestimate stone size, measuring stones at an average of nearly 9 mm when CT measured them at about 5.5 mm.²² That said, a large randomized trial found that starting with ultrasound rather than CT did not lead to worse outcomes in terms of return emergency visits, hospitalizations, or diagnostic accuracy for patients with suspected stones.²³ Many emergency departments now use ultrasound first and reserve CT for cases where the diagnosis remains unclear.

TENS and Complementary Approaches

Transcutaneous electrical nerve stimulation (TENS), a device that delivers mild electrical pulses through skin pads, is sometimes tried for chronic flank or back pain. The theory is that the electrical signals can dampen pain transmission in the nervous system.²⁴ However, the research on TENS for chronic low back pain is disappointing. A Cochrane review found no statistically significant differences between active TENS and sham (placebo) TENS for any outcome measured.²⁵ A controlled trial reinforced this, finding about 47% improvement in pain indicators with real TENS versus 42% with sham, a difference that was not statistically or clinically meaningful, and no added benefit when TENS was combined with exercise.²⁶ TENS is safe and inexpensive, so some people find it worth trying, but the evidence does not support it as a reliable treatment for chronic pain in this area.

Flank Pain During Pregnancy

Pregnancy creates a unique challenge for flank pain. The growing uterus naturally compresses the ureters, which can mimic or mask kidney stone symptoms. Imaging options are limited because CT scans expose the fetus to radiation, so ultrasound is the recommended first-line tool, and MRI without contrast can be used for complex cases.²⁷

For treatment, conservative management with fluids, safe pain relief (typically acetaminophen), and monitoring remains the first approach. When a stone causes infection or will not pass, ureteroscopy has emerged as a safe option that can clear the stone definitively. A review of the current evidence noted that ureteroscopy can be less burdensome than the traditional alternative of placing a temporary ureteral stent or nephrostomy tube, which require regular exchange during pregnancy because they encrust faster in pregnant patients.²⁸ NSAIDs are generally avoided during pregnancy, especially in the third trimester, so pain management requires close coordination with an obstetrician.

Dietary Changes That Reduce Recurrence

If kidney stones are behind your flank pain, what you eat matters almost as much as how much you drink. The UK Biobank study found that every additional 100 grams of fruit consumed daily was associated with a roughly 12% lower risk of developing stones, and higher fiber intake showed a similar protective effect. On the other hand, higher meat consumption and routinely adding salt to food were both linked to increased stone risk.⁸ One common misconception is that you need to avoid calcium to prevent calcium-based stones. The opposite tends to be true: dietary calcium binds oxalate in the gut before it reaches the kidneys, so adequate calcium from food (not supplements) actually lowers stone risk for most people.

The type of fluid you drink also plays a role. A systematic review found that grapefruit, apple, and orange juices reduced the saturation of calcium oxalate in urine, while cranberry juice increased it.⁷ People who have had one stone have about a 50% chance of getting another within ten years, so these dietary adjustments can make a real difference over time.