D-mannose is a supplement that may help treat and prevent urinary tract infections (UTIs). It may block the activity of a specific type of bacteria that causes UTIs.

D-mannose is a type of simple sugar that’s related to glucose. Both sugars occur naturally in your body and some plants in the form of starch.

Some people use it to treat and prevent urinary tract infections (UTIs), as it may reduce the number of certain bacteria that cause UTIs.

Keep reading to learn about D-mannose, its potential benefits and side effects for treating UTIs, and how to use it.

A UTI is a bacterial infection of the urinary tract, which includes your bladder and urethra, as well as the tubes that carry urine from the kidney to the bladder. While various bacteria and fungi can cause a UTI, about 85% of infections result from E. coli. Once these bacteria enter the urinary tract, they latch onto cells, where they grow and cause infection.

Treatment typically involves antibiotics to target those bacteria. However, antibiotics may cause side effects and contribute to antibiotic-resistant strains of bacteria. Some non-antibiotic remedies may help prevent or treat UTIs.

A 2024 study suggests that consuming d-mannose may prevent bacteria from adhering to the lining of the urinary tract.

After consuming D-mannose foods or supplements, your body eventually eliminates it through the kidneys and into the urinary tract. But while it’s in the urinary tract, D-mannose can attach to E. coli bacteria that may be there. As a result, the bacteria can no longer attach to cells and cause infection.

Treatment

While UTIs may go away on their own without treatment, many people seek medical care because of symptoms such as:

  • pain and burning
  • urinary frequency
  • urinary urgency

D-mannose may help reduce UTI symptoms in women with an active infection.

A 2022 review of studies on non-antibiotic treatment for UTIs found that D-mannose alone or combined with other remedies seemed more effective than other remedies. However, the authors noted that many of the studies were small and that not all used the same definition of UTI.

They also suggest combining non-antibiotic and antibiotic treatments in future research, hypothesizing that it may shorten the time on antibiotics. However, larger, randomized studies are needed.

Learn more about herbal remedies for UTIs.

Prevention

D-mannose may help prevent UTIs by reducing the amount of E. coli in the urinary tract.

Another review of research examined 14 studies on D-mannose and its effectiveness in preventing UTIs and found that 13 suggested D-mannose may be effective for prevention. However, the authors mention that no guidelines currently exist.

While D-mannose has shown some promise in preventing UTIs, more research is needed before doctors can formally recommend it.

Additional studies are currently underway.

You may be able to take additional steps to help prevent UTIs.

Complicated UTIs

People who may have of a complicated UTI typically need urgent medical attention for a UTI.

This can include people:

  • with a penis
  • with a compromised immune system
  • who received a kidney transplant
  • using a cathter
  • who have severe or concerning symptoms or symptoms that affect the whole body, such as fever, confusion, or nausea

When deciding on which D-mannose product to use, consider the following:

  • whether you’re trying to prevent an infection or treat an active infection
  • the dose you’ll need to take
  • the type of product you want to take
  • whether the product is third-party verified

People may use D-mannose to prevent or treat UTIs. Knowing which of these you are using it for is important because the dosage will differ.

The best dose to use isn’t entirely clear, however. For now, only the doses used in research typically include:

  • For preventing frequent UTIs: 2 grams once daily, or 1 gram twice daily
  • For treating an active UTI: 1.5 grams twice daily for 3 days, and then once daily for 10 days; or 1 gram three times daily for 14 days

D-mannose comes in capsules and powders. The form you choose mainly depends on preference. You might prefer a powder if you don’t like to take capsules or want to avoid the fillers included in some manufacturers’ capsules.

Keep in mind that many products provide 500-milligram capsules. You may need two to four capsules to get the desired dose.

To use D-mannose powder, dissolve it in a glass of water and then drink the mixture. The powder dissolves easily, and the water may have a sweet taste.

It’s best to talk with a doctor before taking any supplements, as they can potentially cause side effects or interact with other medications you may be taking.

How to get D-mannose from your diet

Regularly eating certain foods that contain D-mannose may potentially help prevent UTIs.

Several fruits and vegetables contain D-mannose, including:

This sugar is also found in certain nutritional supplements, available as capsules or powders. Some contain D-mannose by itself, while others include additional ingredients, such as:

  • cranberry
  • dandelion extract
  • hibiscus
  • rose hips
  • probiotics

Learn more about diet and UTI prevention.

Most people who take D-mannose don’t experience side effects, but some might have loose stools or diarrhea.

If you have diabetes, talk with your doctor before taking D-mannose. Since D-mannose is a form of sugar, it makes sense to be cautious. If you take D-mannose, your doctor might want to monitor your blood sugar levels more closely.

If you have an active UTI, it’s best to talk with a doctor. Although D-mannose might help treat infections in some people, the evidence isn’t very strong.

Delaying treatment with an antibiotic can result in the infection spreading into the kidneys and blood, which can be an emergency.

More research needs to be done, but D-mannose may be a promising option for treating and preventing UTIs, especially in people with frequent UTIs. Since researchers are still conflicted, it is best to stick with proven methods.

Most people who take it don’t experience any side effects, but higher doses may cause health issues yet to be discovered.

If you have an active UTI, talk with a doctor about appropriate treatment options. Although D-mannose might help treat a UTI for some people, it’s important to follow medically proven methods of treatment to prevent the development of a more serious infection.

Researchers are also investigating other natural methods for preventing UTIs, including probiotics. It is best to talk with a doctor about options for preventing UTIs, especially if you get them often.