If you’ve ever had a urinary tract infection, you know the pain-in-the-ass symptoms that come with it: a burning sensation when you pee, the need to go all the time. Well, those symptoms are also indicators of another serious health issue: a kidney infection.

While kidney infections are rare in otherwise healthy people, most do start as a UTI. “As soon as you start having other symptoms [besides burning, frequency, and urgency], that’s when you worry it might be moving beyond the bladder,” says Staci Leisman, M.D., internist and nephrologist at Mount Sinai Hospital. “It’s called an ascending infection—it literally moves up from the bladder into the kidneys.”

A kidney infection can be easily treated with oral antibiotics (it usually takes about a week to clear up), says Leisman. But in rare cases, an untreated kidney infection can progress to septic shock, which can be fatal. Other worst-case scenarios: super-high blood pressure, leading to kidney failure or kidney scars, which can cause chronic kidney disease.

Chances are, if you’re experiencing the uncomfortable symptoms of a UTI, you’re going to head to your ob-gyn ASAP. But if for some reason you’ve been putting it off, and you start to notice any of the symptoms below, you could be at risk for developing a kidney infection.

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1. Burning Pain With Urination

If you want to get fancy, this is called dysuria, and it’s common in women’s health issues like yeast infections and vaginal infections. “Inflammation along the lining of the urethra can cause that sort of burning sensation when you go to the bathroom,” says Leisman.

2. Urinary Frequency

Not only will you feel like you have to go 20 times a day, you’ll go to the bathroom and very little will come out. “Your bladder is well-designed to hold lots of urine,” says Leisman, “But if there’s irritation happening in the bladder as the result of an infection, that irritation makes you think you have to go all the time.”

3. Urinary Urgency

This is that feeling like you have to pee and you have to pee now. That same irritation in your bladder that causes you to feel like you have to go all the time is what makes it feel like to have to find a bathroom immediately.

4. Fever

People with kidney infections tend to have very high fevers. “We’re not entirely sure why this is, but you’d be looking at temperatures over 100,” says Leisman. “You could also have chills, night sweats, and other things that are more predisposing to a systemic infection.”

5. Back, Side, or Groin Pain

Your kidneys are located deep against the back muscles in your upper abdominal area, so it’s common to experience pain in that region. “If I’m examining you, I’m going to first tap you on the back where your kidneys are and people with a kidney infection will likely jump right off the table from the pain,” says Leisman. “That’s because your kidneys are in a capsule where there’s not a lot of space, so if it gets inflamed at all, it’s incredibly painful.”

6. Abdominal Pain

In addition to back, side, or groin pain, some people with kidney infections may experience abdominal pain. “It’s less likely, but sometimes the pain can manifest in strange places,” says Leisman—and considering that your kidneys are located deep in your abdominal region, it wouldn’t be the weirdest place to feel aches or even sharp pains.

7. Nausea and Vomiting

In the same way a kidney infection can cause systemic symptoms like fever and chills, it can also make you feel sick to your stomach or like you want to throw up all the time. “With any infection, you’ll be feeling pretty unwell, and nausea and vomiting typically come right along with that,” says Leisman.

8. Pus or Blood in Your Urine

In most cases, your doctor would only see this if they did a dipstick urine test. “It’s because your urethra is inflamed and it could be shedding a little bit of blood,” she explains. However, it is is possible that you might actually see blood when you go to the bathroom. As for pus, that would be more common in very complicated kidney infections, and would show up as white cells on the dipstick test.

9. Cloudy or Smelly Urine

One major difference between kidney infections and other vaginal issues is that kidney infections do not come with any discharge. So if you’re experience discharge, you can rule out a kidney infection as the culprit. “But you can have stinky or cloudy urine,” says Leisman. “You’re basically growing bacteria in there, which can sometimes create an odor or cloudiness, which is really just the bacteria and the white cells that you’re seeing.”

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Ashley Mateo
Ashley Mateo is a writer, editor, and UESCA- and RRCA-certified running coach who has contributed to Runner’s World, Bicycling, Women's Health, Health, Shape, Self, and more. She’ll go anywhere in the world once—even if it’s just for a good story. Also into: good pizza, good beer, and good photos.