Possible side effects of OPC grape seed extract are not known and have not yet been thoroughly investigated. However, OPC has a slightly blood-thinning effect and should not be taken with blood-thinning medication. A doctor or pharmacist should always be consulted.
The recommended daily dose of OPC is between 150 - 500 mg. The daily amount depends on whether OPC is used only as a preventive measure or also in case of illness. In general, the daily requirement of OPC depends on various factors. These include age, sex, body weight, height and above all the general metabolic situation.
OPC is the short form for oligomeric proanthocyanidins. In general, one also speaks of vitamin P. It is a herbal agent which has antioxidative and anti-inflammatory properties. This substance belongs to the group of polyphenols, but is assigned to flavanols due to its chemical structure.