Skip to main content
Supplement ScienceSupplementScience

Bilberry Side Effects & Safety

Evidence:Moderate
·

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 gastrointestinal upset in some individuals
  • Potential blood-thinning effect at high doses
  • Rare allergic reactions in berry-sensitive individuals
  • Possible interference with blood sugar regulation

Drug & Supplement Interactions

  • Anticoagulants (warfarin, aspirin) — anthocyanins may have mild antiplatelet effects
  • Diabetes medications — bilberry may modestly lower blood sugar
  • Antiplatelet drugs — potential additive effect on bleeding risk

Maximum Dose

Do not exceed: 600 mg/day of standardized extract; higher doses not well studied

Full Bilberry Guide

References

  1. RCTOzawa Y, Kawashima M, Inoue S, et al. (2015). Bilberry extract supplementation for preventing eye fatigue in video display terminal workers. Journal of Nutrition, Health and Aging. DOI PubMed
  2. Canter PH, Ernst E (2004). Anthocyanosides of Vaccinium myrtillus (bilberry) for night vision — a systematic review of placebo-controlled trials. Survey of Ophthalmology. DOI PubMed
  3. ReviewKalt W, Cassidy A, Howard LR, et al. (2020). Recent Research on the Health Benefits of Blueberries and Their Anthocyanins. Advances in Nutrition. DOI PubMed
  4. ReviewGrohmann T, Litts C, Horgan G, Zhang X, et al. (2021). Efficacy of Bilberry and Grape Seed Extract Supplement Interventions to Improve Glucose and Cholesterol Metabolism and Blood Pressure in Different Populations-A Systematic Review of the Literature.. Nutrients. DOI PubMed
  5. Ulbricht C, Basch E, Basch S, Bent S, et al. (2009). An evidence-based systematic review of bilberry (Vaccinium myrtillus) by the Natural Standard Research Collaboration.. Journal of dietary supplements. DOI PubMed
  6. ReviewCanter PH, Ernst E (2004). Anthocyanosides of Vaccinium myrtillus (bilberry) for night vision--a systematic review of placebo-controlled trials.. Survey of ophthalmology. DOI PubMed
  7. Meta-analysisTalebi S, Shirani M, Mahdavi A, Bagherniya M, et al. (2025). Investigating the Effects of Vaccinium myrtillus Supplementation on Cardiometabolic Indices: A Systematic Review and Meta-Analysis.. Phytotherapy research : PTR. DOI PubMed
Show 5 more references
  1. Kara M, Hasbal-Celikok G, Wilson J, Gómez-Serranillos P, et al. (2025). In vitro mechanistic studies and potential health benefits of a standardized bilberry extract in low mood and cognitive enhancement.. Frontiers in nutrition. DOI PubMed
  2. Nobile V, Dudonné S, Kern C, Roveda G, et al. (2024). Antiaging, Brightening, and Antioxidant Efficacy of Fermented Bilberry Extract (Vaccinium myrtillus): A Randomized, Double-Blind, Placebo-Controlled Trial.. Nutrients. DOI PubMed
  3. Szumny D, Kucharska AZ, Czajor K, Bernacka K, et al. (2024). Extract from Aronia melanocarpa, Lonicera caerulea, and Vaccinium myrtillus Improves near Visual Acuity in People with Presbyopia.. Nutrients. DOI PubMed
  4. Grohmann T, Walker AW, Russell WR, Hoggard N, et al. (2023). A grape seed and bilberry extract reduces blood pressure in individuals at risk of developing type 2 diabetes: the PRECISE study, a double-blind placebo-controlled cross-over intervention study.. Frontiers in nutrition. DOI PubMed
  5. Chan SW, Chu TTW, Choi SW, Benzie IFF, et al. (2021). Impact of short-term bilberry supplementation on glycemic control, cardiovascular disease risk factors, and antioxidant status in Chinese patients with type 2 diabetes.. Phytotherapy research : PTR. DOI PubMed