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D-Mannose Side Effects & Safety

Evidence:Moderate
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This content is for informational purposes only and does not constitute medical advice. Statements about dietary supplements have not been evaluated by the FDA and are not intended to diagnose, treat, cure, or prevent any disease. Individual results may vary — consult your healthcare provider before starting any supplement. Full disclaimer

Safety Profile

Overall safety rating: Generally Safe

Potential Side Effects

  • Mild GI symptoms — bloating, loose stools, or diarrhea at higher doses (most common; it is a sugar alcohol)
  • Nausea (uncommon)
  • Generally very well-tolerated — significantly fewer side effects than antibiotic prophylaxis

Drug & Supplement Interactions

  • Diabetes medications — D-mannose is a sugar, but minimal amounts are metabolized; still, monitor blood glucose in diabetic patients
  • Antibiotics — no negative interaction; can be used alongside antibiotics for acute UTI treatment
  • Anticoagulants — no known interaction

Maximum Dose

Do not exceed: 8-10g daily during acute episodes has been used anecdotally; 2g daily is the standard preventive dose

Full D-Mannose Guide

References

  1. RCTKranjčec B, Papeš D, Altarac S (2014). D-mannose powder for prophylaxis of recurrent urinary tract infections in women: a randomized clinical trial. World Journal of Urology. DOI PubMed
  2. Meta-analysisVargas CEF, Mutarelli A, Menegardo LG, Silva AKBD, et al. (2025). Efficacy of D-mannose as prophylaxis of recurrent urinary tract infection: a systematic review and meta-analysis of randomized controlled trials.. Jornal brasileiro de nefrologia. DOI PubMed
  3. Meta-analysisLenger SM, Bradley MS, Thomas DA, Bertolet MH, et al. (2020). D-mannose vs other agents for recurrent urinary tract infection prevention in adult women: a systematic review and meta-analysis.. American journal of obstetrics and gynecology. DOI PubMed
  4. ReviewCooper TE, Teng C, Howell M, Teixeira-Pinto A, et al. (2022). D-mannose for preventing and treating urinary tract infections.. The Cochrane database of systematic reviews. DOI PubMed
  5. Kyriakides R, Jones P, Somani BK (2021). Role of D-Mannose in the Prevention of Recurrent Urinary Tract Infections: Evidence from a Systematic Review of the Literature.. European urology focus. DOI PubMed
  6. Singh RG, Nguyen E, Zhao Y, Zhang C, et al. (2026). A randomized, triple-blind, placebo-controlled, parallel study of the efficacy of D-mannose for urinary tract infection symptoms in women.. Current urology. DOI PubMed
  7. Riemma G, Vinci D, La Verde M, Caniglia FM, et al. (2025). Adding collagen, propolis plus quercetin, bacillus coagulans, hyaluronic acid and chondroitin sulphate to D-mannose avoids symptoms and prevents recurrence in women with recurrent urinary tract infections: a single-blind randomized controlled trial.. Expert review of anti-infective therapy. DOI PubMed
Show 4 more references
  1. Wang J, Mei L, Wen H, Yang Y, et al. (2025). D-mannose enhances immune function and modulates gut microbiota composition in adult cats: A randomized controlled trial.. Research in veterinary science. DOI PubMed
  2. Rau M, Santelli A, Martí S, Díaz MI, et al. (2024). Randomized clinical trial of non-antibiotic prophylaxis with d-Mannose plus Proanthocyanidins vs. Proanthocyanidins alone for urinary tract infections and asymptomatic bacteriuria in de novo kidney transplant recipients: The Manotras study.. Nefrologia. DOI PubMed
  3. Kyzlasov P S, Neymark B A, Kuzmenko A V, Abuev G G, et al. (2024). [Experience with UroBest in patients with acute cystitis].. Urologiia (Moscow, Russia : 1999). PubMed
  4. RCTSalvatore S, Ruffolo AF, Stabile G, Casiraghi A, et al. (2023). A Randomized Controlled Trial Comparing a New D-Mannose-based Dietary Supplement to Placebo for the Treatment of Uncomplicated Escherichia coli Urinary Tract Infections.. European urology focus. DOI PubMed