How long kidney pain lasts depends entirely on what’s causing it. A kidney stone can produce waves of sharp pain lasting 20 to 60 minutes at a time, recurring over days or weeks until the stone passes. A kidney infection typically causes steady, worsening pain that begins to ease within two to three days of starting antibiotics. And muscle-related back pain, which is often mistaken for kidney pain, behaves differently from both. Understanding the cause is the fastest way to predict the timeline.
Kidney Stone Pain: Days to Weeks
Kidney stones are the most common reason people search for information about kidney pain. The pain comes in waves called renal colic, often described as one of the most intense pains a person can experience. Each episode typically hits suddenly, peaks within minutes, and lasts anywhere from 20 minutes to over an hour before easing. These episodes can repeat multiple times a day as the stone moves through the urinary tract.
The total duration from first twinge to stone-free depends on the stone’s size. Stones smaller than 4 millimeters pass on their own about 80 percent of the time, taking an average of 31 days. Stones between 4 and 6 millimeters still pass naturally around 60 percent of the time, but the average stretches to 45 days. Stones larger than 6 millimeters rarely pass without medical help. Only about 20 percent come out on their own, and when they do, the process can take up to a year.
The pain isn’t constant throughout this entire period. You may feel nothing for days between episodes, then get hit with another wave as the stone shifts position. The worst pain usually occurs when the stone enters the ureter, the narrow tube connecting the kidney to the bladder. Once it drops into the bladder, the intense flank pain typically stops, though you may feel burning or pressure during urination as it exits.
Kidney Infection Pain: Improving Within Days
A kidney infection (pyelonephritis) produces a different kind of pain: a deep, steady ache on one side of the back, often accompanied by fever, nausea, and painful urination. Unlike stone pain, which comes and goes, infection pain tends to be constant and worsening until treatment begins.
Most people start feeling noticeably better within 48 to 72 hours of starting antibiotics, though the full course of medication usually runs 7 to 14 days. About 12 percent of patients return with persistent symptoms early in treatment, often within the first day, and some of those require hospitalization for stronger medications. By a week after completing the full antibiotic course, roughly three-quarters of patients have complete symptom resolution and a negative urine culture.
If your pain is not improving after two to three days on antibiotics, that’s a signal the infection may not be responding to the prescribed medication or that something else is going on, such as a stone blocking drainage from the kidney.
Polycystic Kidney Disease: Minutes to Days
People with polycystic kidney disease (PKD) experience recurring pain episodes that vary widely. According to the NHS, pain in the abdomen, side, or lower back is often the first noticeable symptom of PKD and can be severe but is usually short-lived, lasting from a few minutes to several days. These flare-ups can be triggered by a cyst enlarging, bleeding into a cyst, a kidney stone forming, or a urinary tract infection developing alongside the cysts.
Unlike a one-time kidney stone, PKD pain tends to come back. Some people develop chronic, lower-level discomfort between acute episodes as the kidneys enlarge over time. The acute flares resolve, but the baseline discomfort may gradually increase over years.
Pain After Kidney Procedures
If you’ve had a procedure to remove a kidney stone, such as ureteroscopy or shock wave lithotripsy, expect some pain during recovery. A temporary stent is often placed to keep the ureter open while it heals, and this stent itself can cause cramping, bladder pain, and discomfort during urination. These symptoms are normal and generally improve within a few days.
The stent is typically removed a few days to a couple of weeks after the procedure. You should be able to return to normal activities a few days after the stent comes out, though mild soreness and occasional blood in the urine may linger briefly. If pain worsens rather than improves after a procedure, that can indicate a complication like infection or a remaining stone fragment.
How to Tell It’s Your Kidney, Not Your Back
Many people experiencing one-sided back pain aren’t sure whether it’s muscular or kidney-related. There are a few reliable differences. Kidney pain typically sits higher than most people expect, just below the ribs on one or both sides of the spine. It does not improve or worsen when you change position, and it generally won’t get better without treatment. Muscular back pain, by contrast, tends to feel like a dull ache or stiffness that worsens with certain movements and improves when you shift to a more comfortable position.
Kidney pain also tends to come with other symptoms that back pain doesn’t: changes in urination (color, frequency, burning), fever, or nausea. If your pain is deep, one-sided, unaffected by movement, and paired with any urinary symptoms, the source is more likely your kidney than your muscles.
When Pain Doesn’t Follow the Usual Timeline
The timelines above cover the most common scenarios, but kidney pain that doesn’t resolve within expected windows can signal a more serious issue. A kidney stone that causes persistent pain for more than a few days without passing may be too large to clear on its own or may be stuck in a position that’s blocking urine flow. Blocked drainage can cause the kidney to swell (hydronephrosis), and once that obstruction is cleared with a stent or other intervention, pain typically improves within a few days.
Kidney infection pain that persists beyond the first few days of antibiotics may mean the bacteria are resistant to the medication, or that an abscess has formed. And any kidney pain that’s accompanied by high fever, inability to keep fluids down, or blood in the urine warrants prompt medical evaluation rather than a wait-and-see approach.