6 Serious Side Effects Of Grape Seed Extract

Medically Reviewed by Mary-Walker Hall, RDN
By Tanya Choudhary

Made from the seeds of grapes, grape seed extract is rich in antioxidants and several other nutrients. Commonly used as a dietary supplement, grape seed extract may benefit your health in the long term and reduce the risk of developing medical conditions. What you are probably not aware of are the many side effects of grape seed extract. In this article, we take a deeper look at the reported side effects and how they may impact your health.

Grape Seed Extract – A Brief

Well, as evident from its name, grape seed extract comes from grapes and has a high concentration of Vitamin E, linoleic acid, flavonoids and phenolic procyanidins. Grape seed extract is derived from grape seeds that are extracted, dried and purified to produce polyphenolic compounds-rich extract that also has well documented antioxidant, antimicrobial and anti-inflammatory properties (1).

It is mostly used for industrial purposes while oral grape seed extract is used in capsules or tablets. Grape seed extract is believed to have potential health benefits. It is a rich source of antioxidants and oligomeric proanthocyanidins which possess several health benefits.

Though there is a lack of scientific evidence about the potential health benefits of grape seed extract, it does have some adverse effects associated with it. Besides, there is dearth of information regarding the recommended dose of grape seed extract which further increases the risk. Doses of between 100-300 milligrams/day have been used in studies and are prescribed in some European countries (2).

Grape Seed Extract Side Effects

Given below are some of the grape seed extract side effects which can turn out be serious:

1. Bleeding

One of the most prominent side effects of grape seed extract is bleeding, both internal and external. It can slow down blood clotting, thus leading to prolonged bleeding in cuts and bruises. Grape seed extract can also cause internal bleeding that includes symptoms of gastrointestinal bleeding like blood in vomit, bright red blood in stools, and tarry stools.

Since grape seed extract slows down blood clotting, it is not suitable for those having to undergo surgery as it might cause extra bleeding. Hence, the use of grape seed extract should be stopped at least two weeks before a scheduled surgery.

2. Hemorrhagic Stroke

One of the most serious side effects of grape seed extract is hemorrhagic stroke, which is also a form of internal bleeding. It is characterized by the bursting of blood vessels inside the brain. The blood clot inside the brain irritates the brain tissues and causes swelling.

Symptoms of hemorrhagic stroke include coma, unconsciousness, headache, nausea, difficulty in swallowing, vision or speech impairment, weakness or numbness in arms or legs, loss of coordination, etc.

3. Allergic Reactions

Grape seed extract can also cause allergic side effects like rashes, itching, swelling of lips, mouth, tongue or throat, hives, difficulty in breathing or wheezing, etc. It is advisable to seek immediate medical attention if any of these allergic reactions is observed.

4. Unsuitable For Pregnant And Nursing Women

Pregnant women and those trying to conceive should avoid using supplements having grape seed extract as an ingredient, as these supplements have no medical recommendation. Besides, nursing women should consult their gynaecologist before using grape seed extract. This is because grape seed extract is considered a herbal medicine and herbal medicines are not standardized.

5. Drug Interactions

Due to its potential blood thinning effects, grape seed extract can react with certain drugs, that include medicines for blood thinning. It also can react with anti-platelet drugs as well as pain relieving drugs like aspirin and ibuprofen. Cholesterol lowering drugs and prescription drugs like Methotrexate can also react with it. Hence, grape seed extract should not be used with any of these medications without medical advice.

6. Other Minor Side Effects

Grape seed extract may also cause adverse effects like dry or itchy scalp, dizziness, and nausea (3). Intake of grape seed extract may lead to other minor side effects like dry mouth, sore throat, cough, infections, abdominal pain, stomach upset, indigestion, and muscular problems.

Despite its common use in dietary supplements and capsules, grape seed extract may be harmful if consumed in excessive amounts. The side effects of grape seed extract range from increased risk of bleeding to hemorrhagic stroke. Furthermore, it may cause dry scalp, indigestion, sore throat, or dizziness. In some cases, grape seed extract may trigger allergic reactions or interfere with the functioning of certain medications, especially blood thinners. Avoid such complications by limiting your intake or abstaining from it altogether. Go for the supplement only after consulting your doctor.

Frequently Asked Questions

Can you take grape seed extract every day?

Yes. Moderate consumption of grape seed extract can benefit your health in many ways. However, excess intake may lead to a few adverse effects.

What time of day should you take grape seed extract?

You can take grape seed extract whenever you want to, at any time of the day.

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Tanya is an ISSA certified Specialist in Fitness & Nutrition. She specializes in writing articles on ingredients that benefit skin,... more

Mary-Walker Hall

(BS (Food, Nutrition, & Dietetics))
Mary-Walker Hall is a Registered Dietitian Nutritionist who has a passion for equipping parents and caregivers with the tools to... more