Anthocyanosides, a group of flavonoid compounds found in berries such as bilberry (Vaccinium myrtillus), have been used in Europe for vascular health, including conditions like phlebitis (inflammation of a vein). The scientific basis for their use is tied to their antioxidant properties and their ability to strengthen capillaries and blood vessel walls. Several small clinical studies and animal experiments suggest anthocyanosides may reduce capillary fragility, improve microcirculation, and exert anti-inflammatory effects. For example, bilberry extracts standardized for anthocyanosides have shown some benefit in improving symptoms of chronic venous insufficiency, which can be related to phlebitis, by reducing edema and feelings of heaviness in the legs.

However, direct evidence specifically for phlebitis is limited. Most research focuses on broader venous disorders, and there are few high-quality randomized controlled trials isolating anthocyanoside effects on phlebitis itself. Thus, while there is some scientific rationale and preliminary clinical data supporting vascular benefits, the evidence for anthocyanosides as a treatment for phlebitis is weak to moderate (rated here as 2 out of 5). More rigorous studies are needed to confirm efficacy and determine optimal dosing and safety.