What are the possible side effects of Bilberry (Vaccinium myrtillus)?
Bilberry is generally believed to be safe in recommended doses for short periods of time, based on its history as a foodstuff. There are no known reports of serious toxicity or side effects, although if taken in large doses, there is an increased risk of bleeding, upset stomach, or hydroquinone poisoning. Based on human use, bilberry fresh fruit may cause diarrhea or have a laxative effect. Based on animal studies, bilberry may cause low blood sugar levels. Caution is therefore advised in patients with diabetes or hypoglycemia, and in those taking drugs, herbs, or supplements that affect blood sugar. Serum glucose levels may need to be monitored by a healthcare provider, and medication adjustments may be necessary. In theory, bilberry may decrease blood pressure, based on laboratory studies. With the use of bilberry leaf extract, there is a theoretical increased bleeding risk, although there are no reliable published human reports of bleeding. Caution is advised in patients with bleedi
