UTI & Diarrhea: Causes & How to Get Relief

Key takeaways:

• Urinary tract infections (UTIs) can cause diarrhea if inflammation from the urinary tract spreads to the digestive system.
• Medications to treat a UTI can also cause diarrhea.
• Diarrhea usually resolves with minimal treatment, but a UTI requires an antibiotic.

Urinary tract infections, particularly those that ascend to the kidney, can spread to the digestive tract and cause infectious diarrhea. Treatment for a UTI can also result in diarrhea.

You may need antibiotics if you have a urinary tract infection and diarrhea. If you’re being treated for a UTI already, contact your doctor about any side effects that concern you, including diarrhea. Otherwise, consult a healthcare professional so you can receive proper care for a UTI and get to the bottom of what’s causing your diarrhea.

Can a UTI cause diarrhea?

A urinary tract infection is an infection of the bladder. The kidneys may be involved if the infection spreads through the ureters to the kidneys. This is known as an upper urinary tract infection. There are several ways that a UTI can lead to diarrhea.

• Chemicals from the urinary tract can cause inflammation and increased motility in the intestine.
• Infection can spread from the urinary system to the digestive tract.
• Antibiotics used to treat UTIs can cause diarrhea.
• Nonsteroidal anti-inflammatory drugs (NSAIDs) used to treat pain in a UTI can cause diarrhea.
• Sometimes, a separate gastrointestinal infection unrelated to the UTI may cause diarrhea.

Complications associated with UTIs and diarrhea

Antibiotics are rarely necessary to treat uncomplicated diarrhea but are required to treat a UTI. If these conditions are untreated, complications can occur.

Complications associated with a UTI are more likely to occur in older people and those with diabetes, urinary tract abnormalities, and who have recently undergone procedures involving the bladder. Some common complications associated with UTIs and diarrhea are explained below.

Upper urinary tract infection (pyelonephritis)

The most common responsible organism is E. coli, a bacteria found in stool. Infection with E. coli occurs often in women because the rectum and urethral opening, where stool and urine are expelled, are close together.

A bladder infection, also known as cystitis, is characterized by symptoms of painful or burning urination, lower abdominal pain, and frequent urination. Urethritis refers to an infection of the urethra.

If the bacteria from the bladder travel to the kidneys through the ureters, the kidneys will become infected. This is known as pyelonephritis. It is a much more severe condition than urethritis or cystitis. Symptoms of an upper UTI can include fever, chills, fatigue, malaise, nausea, vomiting, and pain in the lower abdomen or the area between the lower ribs and spine.

Dehydration

Dehydration can occur due to a UTI accompanied by fever or when you experience nausea and vomiting with a UTI. It can also occur with diarrhea when fluids are not replaced.

Symptoms include thirst, dark urine, light-headedness, and fainting. It’s essential to replace lost fluids to avoid dehydration and electrolyte imbalances.

Acute renal failure

Acute renal failure can be caused by dehydration or damage to the kidneys as a result of the infection. There are several ways kidney failure can occur:

• Direct toxic effects of a virus, bacteria, fungal infection, or parasitic infection
• Nephrotoxic (kidney-damaging) effects of an antibiotic used to treat a UTI
• Immune response to an infection
• Circulating antibodies to an infective organism can damage the kidneys
• Sepsis or multiorgan dysfunction

Bacteremia

Bacteremia occurs when infectious bacteria enter the bloodstream, usually in the case of bacteria from the bladder or kidney. Although bacteremia is usually without symptoms, if untreated, it can lead to sepsis.

Sepsis

Sepsis is a life-threatening condition. It is caused by an exaggerated immune response to a harmful pathogen like a bacteria. Sepsis can lead to multiorgan dysfunction, shock, and death.

Sepsis from a urinary tract infection is more likely in those over 65, survivors of previous sepsis, and people with chronic health issues, like kidney disease or diabetes.

Renal (kidney) abscess

A renal abscess is a collection of pus in the kidney resulting from infection. It occurs when the body’s immune response leads to constriction of blood vessels and local ischemia (lack of oxygen.) The tissues die without oxygen, allowing infectious organisms to seed. A perinephric abscess can also occur around the kidneys, either from local spread or through the bloodstream.

Abscesses require antibiotics and may require drainage depending upon size and location. Drainage can be performed through the skin or surgically.

When to see a doctor about UTIs and diarrhea

You should always see a doctor if you have symptoms of a UTI and diarrhea. If UTIs are not treated, they can lead to serious complications like sepsis or kidney failure.

You should see a doctor if:

• You experience signs of a UTI, such as increased urgency to urinate, burning during urination, and cloudy or bloody urine.
• You have symptoms of cystitis with diarrhea.
• You have a fever.
• Your diarrhea lasts longer than two days.

You should go to the emergency room if:

• Your temperature is higher than 100.4°F/38°C.
• You have other signs of a serious infection, including chills, malaise, fatigue, flank pain, or pain between the lower ribs and spine.
• You experience signs of severe dehydration, such as decreased urine output, dark urine, confusion, or lightheadedness.

Questions to ask your doctor about UTIs and diarrhea

• Do I have signs of a urinary tract infection?
• What organism or bacteria probably caused my UTI?
• Did my UTI cause my diarrhea?
• If you treat the UTI, will my diarrhea resolve on its own?

Treatment options for diarrhea with a UTI

Diarrhea and UTI may be treated separately if a different pathogenic microorganism causes each one. In some cases, treatment of the UTI will treat the underlying cause of diarrhea.

Diarrhea usually goes away without treatment, but medicines that slow the digestive tract can help by easing symptoms and lowering the risk of dehydration.

Antibiotics

Antibiotics are necessary to treat both cystitis and pyelonephritis caused by bacteria. Parasites, viruses (Dengue, hanta, and hepatitis B), and fungi (Candida, aspergillus) can less commonly cause urinary tract infections and may be treated with antibiotics.

Antibiotics are not always needed for infectious diarrhea. However, untreated UTIs can cause serious complications. If the same pathogen caused both conditions, then one antibiotic should treat both. It’s also important to remember that antibiotics used to treat a UTI can cause diarrhea.

Other medications

If you have diarrhea, you may try over-the-counter remedies like bismuth salicylate (Pepto Bismol) or loperamide to slow the passage of food through your GI tract. If these drugs do not work, your doctor may prescribe diphenoxylate and atropine (Lomotil).

Probiotics

Probiotics are live microorganisms that usually inhabit the gut. Taking a probiotic restores a healthy balance of intestinal microorganisms. You may need to take a probiotic supplement to treat diarrhea.

Hydration

It is important to hydrate with either condition. Diarrhea can cause dehydration from the loss of fluids from the GI tract. UTIs can cause dehydration due to fever or loss of appetite. Drink clear fluids and avoid sugary, high-calorie drinks.

Frequently asked questions: UTIs and diarrhea

People with UTIs and diarrhea usually have questions. Here are a few frequently asked questions:

How do you know if a UTI has spread to your kidneys?

If a UTI spreads to the kidneys, it will cause systemic symptoms. These symptoms include high fever, chills, nausea, vomiting, flank pain, and pain between the lower ribs and spine.

However, patients with immune suppression like organ transplant recipients may have many fewer or less severe symptoms. If left untreated, serious complications like sepsis may occur.

What other gastrointestinal problems can UTIs cause?

Urinary tract infections can result in constipation due to painful bowel movements. UTIs can also result in bloating and flatulence.

Final thoughts on UTIs and diarrhea

Urinary tract infections and their treatment can cause diarrhea. This can result from inflammation or the spread of the infection locally or through the bloodstream. In some cases, infectious diarrhea and a urinary tract infection can be caused by different pathogens.

Although diarrhea is usually self-limited, urinary tract infections should be treated with an antimicrobial drug. Other interventions for diarrhea include medications that slow the passage of food through the gastrointestinal tract.

General Medicine follows a strict editorial process, including using real experts to write our articles, vetted primary sources, fact-checking, a secondary medical review, and updates as necessary. This article was medically reviewed and fact checked by Dr. Marjorie Bravard, MD.

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