Grape Seed Extract Side Effects
While most people do not experience problems with grape seed extract, side effects are possible. Some of the adverse effects that may occur include headaches, abdominal pain, dizziness, and sore throat. Potentially serious side effects that should be reported to your healthcare provider immediately include easy bruising, vomiting of blood, and black or tarry stools (all signs of bleeding).
As with most medications or supplements, side effects are possible with grape seed extract. People often assume that natural products are always free of side effects. However, this is simply not the case. Any natural product with the capability to have medicinal properties may also have side effects.
(This article covers many, but not all, of the possible side effects with grape seed extract. Your healthcare provider can discuss a more complete list of grape seed extract side effects with you.)
Possibly bothersome (although usually not serious) grape seed extract side effects may include:
Theoretically, grape seed extract could increase the risk of bleeding, including dangerous internal bleeding. This risk is probably most significant for people with a bleeding disorder or who take "blood thinner" medications (see Grape Seed Extract Drug Interactions). Let your healthcare provider know if you develop any signs of bleeding, such as:
- Easy bruising
- Cuts or scrapes that are slow to stop bleeding
- Signs of gastrointestinal bleeding, including:
- Black, tarry stools
- Bright red blood in the stool
- Vomiting of blood
- Signs of a hemorrhagic stroke (bleeding in the brain), including:
- Vision or speech changes
- Weakness or numbness in an arm or leg
- Severe headache.
Of course, seek immediate medical attention if you develop any signs of an allergic reaction to grape seed extract, such as:
- A rash
- Swelling of the mouth, lips, tongue, or throat
- Wheezing or other difficulty breathing.
Unpredictable grape seed extract side effects are also possible due to inactive ingredients or contaminants in these products. Because dietary supplements are not as tightly regulated as prescription or non-prescription drugs, they are sometimes contaminated with other supplements, medications, or even heavy metals. In order to avoid such problems, it is important to choose grape seed extract products that are made by trustworthy manufacturers. Your pharmacist can help you choose a good, reliable product.