How Do You Get a Kidney Infection?

A kidney infection usually develops when bacteria, most often from a urinary tract infection (UTI), travel upward from the bladder through the ureters to the kidneys. It is treatable, but prompt medical assessment is important because untreated infection can become serious.

Overview: how do you get a kidney infection?

How do you get a kidney infection? In most cases, bacteria enter the urinary tract and cause an infection in the bladder, then travel upward through the tubes that carry urine to the kidneys. This is called pyelonephritis, and it is a type of urinary tract infection that needs timely medical treatment.

The bacteria most commonly involved are Escherichia coli (E. coli), which normally live in the bowel. They can reach the opening of the urethra, enter the bladder, and sometimes move to the kidneys. A kidney infection is not usually spread from person to person, and it is not caused by poor hygiene alone.

Although kidney infections are often treatable with antibiotics, they should not be managed by waiting to see if they pass. A clinician can assess symptoms, test urine, and identify whether there are factors such as a stone or blockage that may need additional care.

How did I catch a kidney infection?

A kidney infection most often starts with a lower UTI. Bacteria may enter the urethra and multiply in the bladder before moving upward. Sexual activity can contribute to bladder infections in some people by helping bacteria move toward the urethra, but it does not mean a kidney infection is a sexually transmitted infection.

When people ask how do you get a kidney infection from a UTI, the key point is that a bladder infection can occasionally progress, especially if treatment is delayed, the bacteria are resistant to a medicine, or urine cannot drain normally. Not every untreated bladder infection becomes a kidney infection, but new fever or back pain alongside UTI symptoms needs urgent assessment.

How do you get a kidney infection from E. coli? E. coli from the bowel is the leading cause because it can naturally be present near the urinary opening. Less commonly, infection reaches the kidneys through the bloodstream from another part of the body, typically in people who are already significantly unwell or have particular medical risks.

Risk can also rise with conditions that slow urine flow, including kidney stones, an enlarged prostate, a narrowed urinary tract, or reflux of urine toward the kidneys. A urinary catheter, recent urinary procedure, diabetes, immune suppression, or previous UTIs may also make infection more likely.

What are the 5 warning signs of a kidney infection?

Kidney infection symptoms can develop quickly, sometimes after symptoms of a bladder infection and sometimes without obvious earlier urinary symptoms. The following five warning signs are particularly important:

• Fever, chills, or feeling suddenly hot and unwell
• Pain in the back, side, or below the ribs, often on one side
• Burning or pain when passing urine
• Needing to urinate more often or urgently, sometimes with cloudy, strong-smelling, or bloody urine
• Nausea, vomiting, marked tiredness, or feeling generally ill

Symptoms vary by person. Older adults may have weakness, confusion, or a sudden decline in usual functioning rather than a high fever. Young children may have fever, irritability, poor feeding, vomiting, abdominal pain, or bedwetting rather than describing urinary discomfort.

Blood in urine can occur with a UTI but has several possible causes. It should be discussed with a clinician, particularly if it persists, recurs, or occurs with severe pain. Symptoms alone cannot confirm a kidney infection, so urine testing is commonly needed.

How do you get a kidney infection in women, men, pregnancy, and children?

Women are more likely to develop UTIs because the urethra is shorter and closer to the anus, making it easier for bowel bacteria to reach the urinary tract. This explains why questions about how do you get a kidney infection in women often begin with prevention of recurrent bladder infections. Men can also develop kidney infections, particularly when urine flow is reduced by an enlarged prostate, stones, urinary tract abnormalities, or catheter use.

How do you get a kidney infection while pregnant? Pregnancy changes the urinary tract and can slow the flow of urine, which makes bacterial growth more likely. UTIs and possible kidney infection during pregnancy should be assessed promptly, even when symptoms seem mild, because treatment helps protect both the pregnant person and the pregnancy.

In children, urine reflux toward the kidneys, constipation, incomplete bladder emptying, and structural differences in the urinary tract can sometimes contribute. Parents or caregivers should seek medical advice promptly for a child with fever without a clear cause, vomiting, side or abdominal pain, painful urination, or new urinary accidents.

Clinicians may investigate repeated infections or severe infections more closely. Urinary tract infections can often be treated effectively, and identifying recurrent triggers or an underlying urinary problem may help lower the chance of kidney involvement.

Diagnosis and treatment options

A clinician will ask about symptoms, medical history, pregnancy status, recent infections, and medicines. A urine sample is usually checked for signs of infection and sent for culture to identify the bacteria and guide antibiotic choice. Blood tests may be used when symptoms are severe or there is concern about complications.

Imaging, such as ultrasound or CT, is not needed for every person. It may be considered if there is severe pain, suspected obstruction, repeated infections, a known urinary tract condition, or symptoms that do not improve as expected. Imaging can help identify problems such as stones or a blocked urinary tract.

Antibiotics are the standard treatment for a bacterial kidney infection. Some people can take tablets at home, while those who are very unwell, unable to keep fluids or medication down, pregnant with significant symptoms, or at higher risk of complications may need hospital care and intravenous antibiotics. Drinking fluids as tolerated and resting may support recovery, but they do not replace antibiotic treatment.

It is important to take antibiotics exactly as prescribed and to contact the treating clinician if symptoms worsen or do not begin to improve. Acıbadem Health Point’s multidisciplinary specialists and JCI-accredited hospitals diagnose and treat urinary infections and related urinary tract conditions for international patients.

Does a kidney infection go away?

A kidney infection can go away with appropriate treatment, usually antibiotics chosen by a clinician. Many people begin to feel better after treatment starts, but recovery time varies depending on the severity of infection, the bacteria involved, and a person’s overall health.

A kidney infection should not be assumed to resolve safely without medical care. Without treatment, bacteria can continue to damage kidney tissue or, in some cases, enter the bloodstream and cause a serious infection. Prompt assessment is especially important during pregnancy, in young children, in older adults, and for people with diabetes, kidney disease, or reduced immunity.

Even if symptoms improve quickly, finishing the full prescribed antibiotic course is important. Follow-up testing may be recommended in selected situations, including pregnancy, recurrent infection, persistent symptoms, or concern that infection has not fully cleared.

What foods cause kidney infections?

No specific food causes a kidney infection. Kidney infections are usually caused by bacteria entering the urinary tract, not by eating particular foods. Foods are also not a substitute for medical treatment when infection symptoms are present.

Regular fluid intake may help some people maintain normal urine flow, although individual fluid needs differ for people with heart, kidney, or liver conditions. Limiting dehydration, not delaying urination when possible, and seeking care for possible bladder infection symptoms can be practical preventive steps.

For people prone to Urology Problem" class="ahp-ilk">recurrent UTIs, a clinician may discuss individual risk factors, bowel habits, urinary tract conditions, sexual health practices, menopause-related changes, or preventive options. Cranberry products and supplements have mixed evidence and should not be relied on to treat an active infection.

Simple measures may reduce some UTI risk: wiping from front to back after using the toilet, urinating when needed, staying adequately hydrated when medically appropriate, and managing constipation. These steps cannot prevent every infection, especially when there is a structural urinary tract problem.

When to seek medical care

Seek same-day medical advice for symptoms that could suggest a kidney infection, including fever with painful urination, pain in the back or side, chills, nausea, vomiting, or feeling markedly unwell. Prompt evaluation is particularly important for anyone who is pregnant, a child, an older adult, or a person with kidney disease, diabetes, a weakened immune system, or a urinary catheter.

Emergency assessment is needed for confusion, fainting, severe weakness, difficulty breathing, severe or worsening pain, persistent vomiting, inability to pass urine, or signs of severe dehydration. These symptoms can indicate a more serious infection or a urinary blockage requiring urgent care.

People with recurrent UTIs, repeated kidney infections, or symptoms that return after treatment should arrange follow-up with a qualified doctor. Further assessment can look for stones, prostate enlargement, reflux, or other causes that may be affecting urine flow.

Frequently asked questions