A kidney infection requires antibiotics. Unlike a mild bladder infection that sometimes resolves on its own, a kidney infection (pyelonephritis) involves bacteria that have traveled up from the bladder into one or both kidneys, and clearing it without prescription treatment is not realistic. Most people recover at home with a course of oral antibiotics lasting 7 to 14 days, though severe cases need hospital care.
How a Kidney Infection Is Diagnosed
If you show up with flank pain, fever, and urinary symptoms, the first step is a urinalysis. This checks your urine for white blood cells (a sign your body is fighting bacteria) and for blood, both of which point toward infection. A urine culture is usually ordered alongside it. The culture identifies the specific bacteria causing the problem and, just as importantly, shows which antibiotics will actually work against it.
Blood tests may be added if the infection looks serious. These help gauge kidney function and check whether bacteria have entered the bloodstream. In some cases, imaging is needed to look for blockages or structural problems. Ultrasound is the most common first choice, but CT scans or MRI may be used if the picture isn’t clear or complications are suspected.
Antibiotic Treatment at Home
Most kidney infections in otherwise healthy adults are treated with oral antibiotics at home. Your doctor will typically start you on an antibiotic right away, sometimes before the urine culture results come back, then adjust the prescription if the culture shows a different drug would work better. The full course usually runs 7 to 14 days depending on the severity and the specific antibiotic chosen.
Finishing the entire course matters even if you feel better within a few days. Stopping early leaves surviving bacteria a chance to multiply again, potentially creating a harder-to-treat infection. Symptoms often begin clearing within the first few days of treatment, but that improvement doesn’t mean the infection is fully gone.
One reassuring detail: once you finish antibiotics and feel well, you don’t need a follow-up urine test to prove the infection is cleared. Current urology guidelines recommend against routine post-treatment urine cultures in patients who no longer have symptoms.
When a Hospital Stay Is Needed
Some kidney infections are too severe or too risky to manage at home. You’ll likely be admitted if you have a high fever that isn’t responding to treatment, persistent nausea or vomiting that prevents you from keeping pills or fluids down, severe or hard-to-control pain, or signs of sepsis (more on that below). People whose outpatient treatment has already failed also need inpatient care.
Certain groups face higher risks from kidney infections and are more likely to be hospitalized as a precaution. This includes pregnant women, people with poorly controlled diabetes, organ transplant recipients, anyone with a weakened immune system, and people suspected of having a blockage in the urinary tract. In the hospital, antibiotics are given intravenously so they reach the bloodstream faster, and fluids can be managed directly.
Warning Signs That Need Emergency Care
A kidney infection can progress to sepsis, which is the body’s dangerous, runaway response to infection. Sepsis is a medical emergency. Watch for a fast heart rate, rapid breathing or shortness of breath, confusion or unusual mental fogginess, fever paired with chills or shaking, very low body temperature, warm or clammy skin, and extreme pain. A drop in blood pressure or a noticeable decrease in urination are also red flags. In some cases, small dark-red spots appear on the skin, signaling a bloodstream infection.
A high heart rate, confusion, or fast breathing can be early signs that the infection is spiraling. If you notice any combination of these while being treated at home, get to an emergency room.
Managing Pain and Discomfort During Recovery
Kidney infections typically cause a deep, aching pain in your back or side, along with fever, chills, and painful urination. Over-the-counter pain relievers can help take the edge off while antibiotics do their work. A heating pad placed on your back or abdomen is another simple way to ease flank pain.
Staying well-hydrated is one of the most useful things you can do during recovery. Drinking enough fluid increases urine volume and void frequency, which helps flush bacteria out of the urinary tract. Research suggests aiming for roughly 2.5 to 3.5 liters of total fluid per day (about 10 to 15 cups), which is more than the standard “eight glasses” advice. In one study, increasing daily water intake to around 2.8 liters reduced urinary tract infection events by 48%. During an active kidney infection, that flushing effect supports what the antibiotics are already doing.
What Recovery Looks Like
Most people notice their fever dropping and pain easing within the first two to three days of starting antibiotics. Energy levels take longer to bounce back. Feeling wiped out for a week or two after a kidney infection is common, especially if the infection was severe or involved a hospital stay. During this window, rest as much as your body asks for and keep your fluid intake up.
If your symptoms aren’t improving after 48 to 72 hours on antibiotics, contact your doctor. This could mean the bacteria are resistant to the drug you were prescribed, or that there’s a complication like a blockage that’s preventing the infection from clearing.
Preventing Future Kidney Infections
Kidney infections almost always start as lower urinary tract infections that climb upward. Preventing that first bladder infection is the most effective shield. A few habits make a measurable difference:
- Drink plenty of water throughout the day. Higher fluid intake dilutes urine and increases how often you urinate, physically washing bacteria out before they can establish an infection.
- Don’t hold your urine. A full bladder gives bacteria time to multiply. Go when you feel the urge.
- Wipe front to back. This keeps intestinal bacteria away from the urethra, where most urinary infections begin.
- Urinate after sex. This helps clear any bacteria that may have been pushed toward the urethra during intercourse.
- Avoid irritating products. Douches, scented sprays, and harsh soaps in the genital area can disrupt the natural bacterial balance and make infections more likely.
- Wear breathable underwear. Cotton fabrics and loose-fitting clothing reduce moisture buildup that encourages bacterial growth.
If you get recurrent urinary tract infections that keep progressing to kidney infections, your doctor may explore additional strategies, including low-dose preventive antibiotics or further testing to check for structural issues in your urinary tract that make you more vulnerable.