What Does a Kidney Infection Feel Like—And When Should You Go to the Hospital?

If you have a vagina, you have likely felt (or will probably eventually feel) the pain of a urinary tract infection (UTI) at some point. It may feel like no big deal at first, but a run-of-the-mill UTI can boost your risk of developing a kidney infection. While the complication is rare, it can become serious, especially if you wait a long time to get treated.

All that is to say: If you’re dealing with UTI symptoms and thinking, “Eh, I can wait a few more days to get those antibiotics,” you may want to reconsider. You’ll be better off dealing with the infection pronto.

But what does a kidney infection feel like? And what causes one in the first place? Here’s what you need to know, including why it’s so important to see a doctor ASAP.

A kidney infection, or what doctors call pyelonephritis, is a type of urinary tract infection that most often originates from the bladder (a lower urinary tract infection) and spreads up into one or both of the kidneys. These infections can be caused by bacteria or viruses, but the bacteria Escherichia coli (E. coli) is a common culprit, according to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Most types of E. coli are usually harmless and found in your intestines, but the bacteria can wreak havoc when they make their way into the urinary tract, according to the Mayo Clinic.

Kidney infections are “one of the most common urologic conditions that we see in general urology practice,” Fara Bellows, MD, a urologist at OhioHealth, tells SELF. And they’re typically easy to treat—as long as you put the kibosh on them early.

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Kidney infections are a type of UTI, but it’s often more aggressive because the bladder infection has spread further up the urinary tract. So, if you hold off on seeking treatment, things can maybe start to get dicey. “This is a serious organ infection and people need to take care of it,” David Kaufman, MD, a urologist at New York’s Central Park Urology, tells SELF. “Bladder infections are uncomfortable, but kidney infections can be deadly.”

As for how long it takes for a bladder infection to turn into a kidney infection? There’s no one-size-fits-all answer, but once infection-causing bacteria make their way from the bladder up into the kidneys, a person’s symptoms can start to intensify very suddenly.

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How do the bacteria get to your bladder in the first place, you ask? Well, usually the bacteria move from the anus (remember, E. coli is common in the GI tract) to the urethra, the small tube that carries urine out of your body—and the entrance to the urinary tract, according to the Mayo Clinic. From there the bacteria can move into the bladder, then into the kidneys through the ureters, which are the tubes that connect the bladder to the kidneys.

Bacteria can more easily make its move from the anus to the urethra if you do things like wipe back to front instead of front to back. More rarely, you can get a kidney infection if bacteria enters your blood during surgery and gets to your kidneys, the NIDDK says.

As for who’s most likely to get them? Certain people are more prone than others. If you’re at a higher risk, it’s even more important to be aware of the possible signs of a kidney infection (which we’ll dig into next). According to the Mayo Clinic, you’re more likely to develop a kidney infection if you have one of the following risk factors:

• You have a vagina: Because the vagina and the anus are anatomically close together and the urethra in a vagina is shorter than the urethra in a penis, bacteria have an easier time getting into the bladder and possibly spreading into the kidneys—in this case, it’s all about the short travel distance.
• You’re pregnant: Anatomical changes that happen when you’re pregnant can increase the risk for kidney infections even more.
• You’ve gone through menopause: After menopause, a drop in estrogen production can cause vaginal dryness, increasing the risk for vaginal irritation that can lead to UTIs, Mehran Movassaghi, MD, urologist and director of Men’s Health at Providence Saint John’s Health Center and assistant professor of urology at Saint John’s Cancer Institute in Santa Monica, California, tells SELF. One highly effective treatment for postmenopausal people with a history of recurrent UTIs is topical vaginal estrogen.¹
• You’re older than 65: As you age, you’re more likely to end up with a kidney infection due to anatomical and urinary tract function changes, Dr. Movassaghi says.
• You have a weakened immune system: Conditions like diabetes and HIV, as well as taking immunosuppressant drugs, can make it harder for your body to fight off the harmful bacteria that can cause a kidney infection.
• You recently used a catheter: Sometimes used after surgery, catheters are used to drain urine from the bladder, but they can also increase infection risk.
• You have other urinary tract issues: Kidney stones, enlarged prostate glands, nerve damage around the bladder, or vesicoureteral reflux (when a small amount of urine flows the wrong way up the urinary tract) may all make a person more prone to a kidney infection.

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“Both bladder and kidney infections share some symptoms such as painful urination, frequency, and urgency, but usually only kidney infections present with back pain, nausea or vomiting, fever, and chills,” Dr. Movassaghi says. This pain is known as flank pain in the medical community and usually presents on either side of your body between your upper abdomen and lower back. You’ll likely notice a deep, dull ache in the area, which is where your kidney pain would likely manifest.

So if you’re a young or middle-aged adult, the signs of a kidney infection are similar to what you might experience in the beginning stages of UTI symptoms with extra unpleasantness thrown on top. Here’s a breakdown of what to look out for:

• Painful urination
• Urgent and frequent urination
• Dark or cloudy urine
• Blood in urine
• Foul-smelling urine
• Fever or chills
• Pain in your back, side, or groin area,
• Nausea or vomiting

An important FYI: Kidney infection signs can differ depending on your age. Adults over 65 might not have any of the typical symptoms and instead present with cognitive issues like confusion, hallucinations, and disorganized speech.

Babies and toddlers, especially girls and uncircumcised boys, can be prone to kidney infections too. (In fact, they’re second only to respiratory infections among very little kids, according to the American Academy of Pediatrics.²) And when children under two are affected, the only symptom they might have is a high fever, notes the NIDDK.

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If you’re feeling signs of a kidney infection, you should seek medical attention as soon as you can, if possible. A kidney infection can be serious because it can sometimes lead to a dangerous, life-threatening health condition called sepsis. (Signs of sepsis include fever, chills, fast breathing, a rapid heart rate, a rash, and confusion, according to the U.S. National Library of Medicine.)

Even if your infection doesn’t progress to that, a kidney infection can become chronic, i.e., long-lasting, and can cause permanent damage to your kidneys. Dr. Kaufman recommends heading to your local urgent care facility or emergency room if you have signs of a kidney infection.

For your doctor, diagnosing a kidney infection is pretty straightforward. They should start with lab tests like a urinalysis, which just involves peeing in a cup on your end. After you hand over your sample, the urine is examined under a microscope to check for the presence of bacteria and infection-fighting white blood cells. To see what kind of bacteria you’re dealing with, the urine should also be cultured over the course of one to three days, according to the NIDDK. (This helps ensure that your doctor uses the best drug available to treat your particular infection. Using the wrong antibiotics can potentially lead to the development of antibiotic resistance, which can make future infections harder to treat.³) In some cases, your doc might also order imaging tests like a CT scan, MRI, or ultrasound to take a closer look at your kidneys.

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A kidney infection is easy to treat if it’s caught in its earliest stage, especially if you’re young and generally healthy. In this case, a course of antibiotics lasting a week to two weeks is usually enough, Dr. Movassaghi says. However, taking the full course of antibiotics is key for fully fighting off the infection, even if you’re feeling totally fine halfway through, so be sure to take every dose, says the NIDDK.

If you have a severe kidney infection (marked by vomiting, nausea, dehydration, low blood pressure, or confusion) or are immunocompromised, you’ll likely need to be treated in the hospital with intravenous antibiotics. After a few days, you should be able to move on to taking antibiotics by mouth.

In rare cases, a person might need surgery for a kidney infection. Usually, this is only considered if your doctor determines there’s something blocking your urinary tract (and causing recurrent infections) like a kidney stone or an enlarged prostate.

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Most people recover 100% from a kidney infection—but there is the possibility of serious complications if one is left untreated. As we mentioned, a kidney infection that doesn’t get treated can cause a condition known as sepsis. This happens when your body responds overzealously to an infection, which can lead to a dangerous drop in blood pressure and cause the body to go into shock, according to the NIDDK. This can make your organs fail, which, in the most extreme cases, can lead to death.

Even in non-life-threatening cases, if you have a kidney infection that becomes chronic, you can wind up with permanent kidney damage that can cause problems like kidney disease or high blood pressure. In pregnant people, untreated kidney infections can also increase the risk of having a baby with low birth weight, notes the Mayo Clinic.

All of that sounds scary, but here’s what’s most important to know: A kidney infection is treatable. It’s all about how soon you seek treatment once you start experiencing kidney infection symptoms.

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Preventing a kidney infection is really all about preventing a urinary tract infection and getting prompt treatment if you ever get one. While you’ve probably heard that guzzling cranberry juice or taking certain supplements can keep UTIs away, the science is far too mixed to consider either of these a definitive way to prevent UTIs, according to the Cleveland Clinic.

Here’s a more science-backed tip to take note of: Whenever you feel a potential bladder infection coming on, make it a habit to drink enough water every day to stay hydrated. That will ensure you’re peeing often enough to help flush out bacteria that could possibly lead to a urinary tract infection. The NIDDK recommends peeing as often as you get the urge, but definitely at least every three to four hours, since urine hanging out in your bladder for too long may help bacteria to grow.

Dr. Kaufman also says peeing after you have sex, if you can, might be helpful if you tend to develop UTIs after sex. There’s not a ton of evidence to back this up as a prevention strategy, but it doesn’t do any harm to make a habit of it. For people with vaginas that get recurrent infections that only happen after sex, your doctor may recommend a single dose of a prophylactic antibiotic that you can take each time you have sex to help prevent infection.⁴

Also, we referenced this above, but it’s important to reiterate: After you pee (or poop, for that matter), you should be sure to wipe from front to back, as wiping back to front can spread harmful bacteria from your rectum to your urethra, where it can cause an infection, the NIDDK notes.

Most importantly, don’t try to get rid of a UTI on your own. “You’ll just make it worse and put yourself at a greater risk of a kidney infection,” Dr. Kaufman says. If you have any bladder or kidney infection symptoms, that’s a clear sign it’s time to seek treatment from a pro.

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Sources:

1. Female Pelvic Medicine & Reconstructive Surgery, Vaginal Estrogen for the Prevention of Recurrent Urinary Tract Infection in Postmenopausal Women: A Randomized Clinical Trial
2. Pediatrics in Review, Pyelonephritis
3. Clinical Focus: Gastroenterology, Hepatology & Nephrology, Treatment of Urinary Tract Infections in the Era of Antimicrobial Resistance and New Antimicrobial Agents
4. American Urological Association, Recurrent Uncomplicated Urinary Tract Infections in Women: AUA/CUA/SUFU Guideline (2019)

Related:

• Is It a UTI or a Yeast Infection? Here’s How to Tell the Difference
• 4 Causes Behind Urine So Foamy It Could Top a Beer
• Is It Sanitary to Pee in the Shower or Should You Stop Immediately?