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d-mannose

D-Mannose is a dietary supplement.

Generic

Not yet rated· sourced from the FDA label
Rated against independent regulatory sources·Last updated June 24, 2026·How we rate
Verified againstopenFDANIH DailyMedRxClass
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Key facts

Active ingredient
D-Mannose
Type
Supplement

What is D-Mannose?

From the FDA label:A simple sugar popularly taken to support urinary-tract health.

What the evidence says

Limited evidence

What D-Mannose is

D-Mannose is a simple sugar (a monosaccharide) that occurs naturally in some fruits, such as cranberries, apples, and peaches, and is also made in small amounts by the body. It is sold as a dietary supplement in powder and capsule form and is most often marketed for urinary tract health.

Commonly used for

Taken by some people in hopes of lowering the risk of recurrent urinary tract infections (UTIs)Used by some people alongside or instead of cranberry products for urinary healthPromoted as a component of "glyconutrient" supplements marketed for general health and immune support

What the evidence shows

High-quality evidence from authoritative US-government sources is limited, and none of the sources reviewed here affirmatively establish that D-Mannose works for its main marketed use. The NIH Office of Dietary Supplements, NCCIH, and MedlinePlus do not publish a dedicated D-Mannose fact sheet, and the MedlinePlus health topic on urinary tract infections does not mention D-Mannose or list it as a recommended way to prevent UTIs. Memorial Sloan Kettering's About Herbs database lists mannose as one of several monosaccharides found in \"glyconutrient\" supplements and, assessing those products' broad health claims, states that strong scientific evidence to support the claims is lacking; that database does not evaluate D-Mannose as a UTI remedy. D-Mannose is not a treatment for an active UTI, which is a bacterial infection that typically requires medical evaluation and antibiotics.

Typical dosage

There is no established or government-recommended dose for D-Mannose, and the authoritative sources reviewed here do not endorse it for preventing or treating infections. Because a suspected UTI can worsen without proper care, talk to a clinician before using D-Mannose rather than self-treating, and seek medical attention promptly for symptoms such as burning during urination, fever, or back pain.

Safety

As a sugar, D-Mannose is generally regarded as well tolerated in short-term use, but rigorous long-term safety data from US-government sources are limited. People with diabetes or blood-sugar concerns, those who are pregnant or breastfeeding, and anyone with kidney problems should check with a clinician before using it. Tell your healthcare providers about any supplement you take so they can manage your care safely.

Side effects

Reported side effects are mostly mild and gastrointestinal, such as loose stools, bloating, or diarrhea, particularly at higher amounts. Comprehensive side-effect data from authoritative government sources are limited, so individual reactions may not be well characterized.

Interactions & cautions

No specific drug interactions are documented by the authoritative government sources reviewed here, but that absence does not guarantee none exist. Because D-Mannose is a sugar, people taking diabetes medications should be cautious, and anyone on prescription drugs should tell their healthcare provider about all supplements they use.

This statement has not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. Summarized from public health authorities; general reference, not medical advice. Talk to a licensed healthcare professional before starting any supplement.

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Information is sourced from public FDA regulatory data. Provided for general reference only — not medical advice. Always consult a licensed professional and the current prescribing information.

What people report to the FDA about D-Mannose

The FDA Adverse Event Reporting System (FAERS) collects reports from patients and clinicians. It holds 650 reports naming D-Mannose, and the FDA flagged 61% of those reports as serious. The effects reported most often — leaving out reports about overdose, misuse or the condition being treated, which dominate the raw list for common medicines:

  • urinary tract infection87 reports
  • fatigue72 reports
  • diarrhoea57 reports
  • headache56 reports
  • arthralgia52 reports
  • nausea51 reports
  • dizziness48 reports
  • dyspnoea37 reports

Read these as a signal, not a rate. A report does not mean D-Mannose caused the effect — anyone can file one, and many describe people taking several medicines for several conditions. Crucially there is no denominator: FAERS does not record how many people took the drug, so these counts cannot be turned into “X% of patients” — a bigger number often just means a more widely used or more talked-about drug. Duplicates exist, and publicity drives reporting. For what is actually established, read the FDA label.

Source: openFDA drug/event (FAERS), retrieved September 25, 2026.

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