Kidney Infection Symptoms: Diarrhea Is More Common Than You'd Expect
Does a kidney infection make you have diarrhea?
Yes, kidney infection can cause diarrhea in some people, although it is not the most common symptom. Major health sources list diarrhea among possible symptoms of pyelonephritis, alongside fever, flank pain, nausea, vomiting, and painful urination.
Why it can happen
A kidney infection is a type of urinary tract infection that has moved up into one or both kidneys, and the body's inflammatory response can affect more than the urinary system. That is one reason some people develop stomach upset, including diarrhea, when they are dealing with a kidney infection.
Diarrhea may also appear because the illness is making you feel generally unwell, because nausea and vomiting are occurring at the same time, or because antibiotics used to treat the infection can loosen stools. In other words, diarrhea can be part of the infection itself, the treatment, or another digestive issue happening at the same time.
Common symptoms
Kidney infections usually cause a recognizable cluster of symptoms, and diarrhea is only one possible part of that picture. NHS guidance lists high temperature, feeling sick, lower back or side pain, aching muscles, and pain or burning when peeing as common symptoms, with diarrhea included as well.
- High fever or chills
- Pain in the lower back, flank, or side
- Nausea or vomiting
- Pain, burning, or stinging when urinating
- Needing to pee more often or urgently
- Diarrhea
How common it is
Diarrhea is not usually the leading sign doctors look for, but it is a documented symptom in patient guidance for kidney infection. Public health resources such as the NHS include it explicitly, which means it is considered a real and clinically relevant symptom even though many patients will not have it.
A practical way to think about it is this: if diarrhea happens with fever, back pain, urinary symptoms, or vomiting, kidney infection becomes more concerning. If diarrhea happens alone, a gastrointestinal virus, food poisoning, medication side effect, or another cause is often more likely.
When to seek care
Kidney infections can become serious if they are not treated promptly, and they can progress to sepsis in severe cases. NHS guidance advises urgent help if symptoms include a very high temperature, shaking chills, back or side pain, blood in urine, vomiting, or not passing urine normally.
- Get medical care quickly if you have fever plus urinary symptoms, especially burning when peeing or flank pain.
- Seek urgent help if you are vomiting, confused, very weak, or unable to keep fluids down.
- Call emergency services if you develop severe illness, confusion, or signs of sepsis.
How doctors sort it out
Clinicians usually do not diagnose kidney infection from diarrhea alone. They look for the full symptom pattern, check urine, and consider whether the infection has spread upward from the bladder to the kidneys.
That matters because diarrhea can also come from other causes, including a stomach virus, antibiotic side effects, or an unrelated bowel problem. A kidney infection becomes more likely when diarrhea appears together with fever, side pain, urinary urgency, cloudy urine, or pain when urinating.
| Symptom | More suggestive of kidney infection | More suggestive of a gut illness |
|---|---|---|
| Fever | Yes, especially with flank pain | Sometimes |
| Back or side pain | Common | Less typical |
| Burning when peeing | Common | Unusual |
| Diarrhea | Possible, but not usually alone | Very common |
| Vomiting | Can happen | Can happen |
What to do now
If you have diarrhea plus symptoms that point to a kidney infection, the safest move is to get checked by a clinician rather than assume it is just a stomach bug. Kidney infections usually need antibiotics, and NHS guidance notes that people often feel better after treatment, but they can be seriously ill before that happens.
While waiting for care, drink fluids if you can, rest, and monitor for worsening symptoms such as fever, chills, dehydration, confusion, or worsening pain. If you cannot keep fluids down or you feel faint, that is a stronger warning sign and should be treated urgently.
A kidney infection is not just "a bad UTI"; it is an upper urinary tract infection that can affect the whole body, which is why symptoms like diarrhea, nausea, and fever may show up together.
What are the most common questions about Kidney Infection Symptoms Diarrhea Is More Common Than Youd Expect?
Can a kidney infection cause diarrhea?
Yes. Diarrhea can occur with a kidney infection, but it usually appears alongside other symptoms like fever, back or side pain, and painful urination rather than by itself.
Is diarrhea the main symptom of a kidney infection?
No. The main symptoms are usually fever, flank or back pain, nausea or vomiting, and urinary symptoms such as burning or urgency, although diarrhea may also be present.
Can antibiotics for a kidney infection cause diarrhea?
Yes. Antibiotics can disturb the gut and cause loose stools, so diarrhea during treatment may come from the medicine rather than the infection itself.
When is diarrhea with a kidney infection an emergency?
It becomes more urgent if diarrhea comes with high fever, severe pain, vomiting, confusion, dehydration, blood in urine, or trouble passing urine, because those can signal a serious kidney infection or sepsis.