What Are The Side Effects Of Eating Too Many Grapes?

Beware of the aftermath of overconsuming grapes because too much of anything is bad, they say.

Medically Reviewed by Madhu SharmaMadhu Sharma, RD
By Ravi Teja TadimallaRavi Teja Tadimalla, Professional Certificate In Food, Nutrition & Health  • 

Grapes are widely consumed by many for the benefits they offer, which can be attributed to their high antioxidant, vitamin, and mineral content. But are you aware of the side effects of grapes associated with their overconsumption?

Some such adverse effects include weight gain, stomach upset, and complications during pregnancy.

Learn more about the other potentially negative effects of grapes. Also, read about which drugs can interact with grapes.

Fun Fact

Grapes are believed to be one of the oldest cultivations grown as far back as 6500 BC, in the Neolithic era.

How Can Grapes Cause Side Effects?

Grapes are small, and one may ingest too many of them. One full cup (92 grams) of grapes contains over 60 calories (1). The small size of grapes makes it easier to overeat them, and this may add calories.

Eating large portions of grapes regularly may lead to weight gain. This is especially true if one doesn’t consciously watch what they eat every day.

Like most fruits, grapes also contain fiber. Consuming excess fiber could lead to constipation (2).

Most of the ill effects of grapes have to do with their excess intake. Though the side effects are not common, it is important you know about them.

What Are The Side Effects Of Grapes?

The salicylic acid in grapes can cause digestive problems. This happens if you overeat grapes. Eating too many grapes in a day may also lead to diarrhea. Weight gain over time is another possible side effect of excess intake of grapes.

1. May Cause Stomach Upset

Woman with stomach ache sitting on a sofa in the living room.

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Grapes contain salicylic acid. Some research highlights an intolerance to this acid, which is characterized by local inflammation of the gastrointestinal tract, abdominal pain, diarrhea, and bloating (3).

Jesse Feder, RDN, says, “Grapes are typically safe regarding acid reflux; however, it is best to avoid sour grapes or grapes that are not very ripe as these have higher acidity.”

In some studies, individuals who had eaten grape seeds experienced appendicitis (4). Undigested seeds or the residue of fruits may also cause acute abdominal pain. However, more research is warranted in this regard.

Grapes may also cause problems if you have irritable bowel syndrome. They contain insoluble fiber that could stimulate the gastrointestinal tract (5). If you have IBS, ensure you do not eat them on an empty stomach.

If you have indigestion or an upset stomach, consuming ginger juice might help. Ginger also helps relieve nausea, especially in the case of pregnancy or other treatments like chemotherapy (6).

2. May Result In Diarrhea

Close-up of a woman clutching her stomach and sitting on the toilet while experiencing pain from diarrhea.

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Foods high in sugar may cause diarrhea. Some research shows that sugar alcohols, organic compounds found in sugar, may lead to diarrhea (7). However, there is insufficient evidence to prove if grapes contain sugar alcohols.

Grape juice may cause diarrhea in susceptible individuals as it contains simple sugars (8).

Some believe grapes may also cause traveler’s diarrhea. This is the form of diarrhea you contract when you visit a different place where the food or sanitary practices are different from where you live. Unpeeled fruits are usually known to cause this form of diarrhea (9).

Traveler’s diarrhea can be problematic as you are away from home. You can cut down this risk by taking drugs like loperamide that can help treat the symptoms of diarrhea (10). Do check with your pharmacist or doctor for the ideal dosage.

Anecdotal evidence suggests that this medication may not be safe for

pregnant women and children under 3 years of age. Consult a doctor for more information.

3. May Lead To Weight Gain

Unhappy woman with excess weight gain touching her drooping belly at home.

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Eating too many grapes in one sitting can make the calories add up quickly. Grapes are high in calories (1). Though there is no research that eating too many grapes could lead to weight gain, binging on them could increase the risk.

Also, you may want to reduce the intake of grapes as a snack. Grapes are lower in calories when compared to cookies and granola bars, but overeating them may lead to weight gain in the long run.

Go for fresh grapes over canned varieties. Canned grapes contain twice as much sugar, and they could contribute to faster weight gain.

The idea that grapes may cause weight gain is not yet validated by research. However, it could be logical to assume that one may overeat grapes as they are small. Make grapes a part of your daily diet – but be wary of the portion sizes (8 to 10 grapes a day should do).

4. May Cause Complications During Pregnancy

This adverse effect can be attributed to the resveratrol in grapes, which is a powerful polyphenol also found in red wine.

In a study, resveratrol supplements were found to cause pancreatic problems in the developing fetus. Though the study doesn’t state anything against grapes, it is better to exercise caution (11).

Some preliminary studies have shown that resveratrol supplementation could actually be beneficial during pregnancy (12). But by and large, studies are inconclusive. Please check with your doctor before taking grapes during pregnancy.

5. May Cause Choking In Kids

A toddler chokes while his father slaps his hand on the back.

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Choking in kids is a prevalent problem. Uncut fruits/vegetables usually can cause choking in kids, especially in those between 6 to 12 months of age. The same could be the case with grapes. This is the period when kids learn to chew and swallow food (13).

Uncut grapes are the problem. Ensure you give your toddler cut grapes to prevent choking.

The reasons grapes are one of the few foods that pose a high risk is their size and shape. A grape has near-perfect dimensions to block a child’s airways. If a child is choking, the following pointers can help (14):

  • If you can see the grape, try removing it with your fingers. Do not blindly poke fingers as you might end up pushing the grape further in. This may make things worse.
  • If you cannot see the fruit and your child is silent or not coughing effectively, please call for help.
  • If your child is conscious but still struggling, try giving back blows. You can do this by laying your child face down along your thighs. Support their head with your hand. Give about five sharp back blows with the heel of your hand in the middle of the back (between the shoulder blades).

This quick video tutorial will help.

6. May Cause Allergies

Close up of a young woman itching her skin.

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Although grape allergy is rare, it can be problematic. A specific protein in grapes, called the grape lipid transfer protein, is found to cause severe allergic reactions in individuals (15).

Grapes can also cause anaphylaxis, which can be life-threatening (16).

Another study reports the case of an 18-year-old female student-developed itching, rashes, and facial swelling after eating grapes (17).

Salicylates are compounds found in most fruits and vegetables, including grapes. Most grape allergies are not life-threatening, except for anaphylaxis.

Anaphylaxis occurs by the release of histamine and other chemicals in the body. This results in leaky blood vessels, eventually leading to the swelling of tissues in the mouth and airways (and dangerously low levels of blood pressure too) (18).

The best-known treatment for anaphylaxis is epinephrine administration. Epinephrine is a chemical in the body that elevates heart rate, and may elevate blood pressure (19).

You can purchase epinephrine from your nearest pharmacy as a pre-filled syringe. It can be immediately injected into the thigh muscle once the symptoms of anaphylaxis are recognized (19).

If you are susceptible to such allergic reactions, keeping an epinephrine injection handy can help.

7. May Aggravate Kidney Problems

Studies have shown acute renal failure in dogs after the ingestion of grapes. After consuming grapes, dogs were reported to have vomited. They also had experienced anorexia (loss of appetite), lethargy, and diarrhea (20).

A report by the National Institute of Diabetes and Digestive and Kidney Diseases suggests that individuals with advanced chronic kidney disease and diabetes limit their intake of certain foods, including grapes (21).

Though no studies have directly linked grapes to adverse kidney effects in humans, you need to exercise caution. If you have any form of kidney ailment, please keep away from grapes and talk to your doctor.

As discussed, grapes are generally safe. They are also incredibly nutritious. But it is important to know the ill effects they can cause. These fruits can also interact with certain drugs. If you are on any form of medication, you should be careful.

Fun Fact
During the fall of the Roman empire, grapes were used in wine-making only in monasteries. However, they quickly became a part of social culture and, by the 16th century, were a staple at social gatherings.

Do Grapes Interact With Any Drugs?

Grapes can interact with the following drugs (22), (23):

  • Haldol
  • Phenacetin
  • Coumadin

This list includes drugs that are broken down by the liver. People who are using blood thinners must avoid excess intake of grapes (occasional intake, in moderation, could be safe) (22), (23), (24). If you are taking any such drugs, you should check with your doctor before consuming grapes.

Infographic: Unexpected Side Effects Of Eating Too Many Grapes

Grapes of better known for their taste and presence of rich antioxidant content. The intake of grapes is linked with many benefits if consumed in moderation. However, excess eating may lead to several side effects. Click on the infographic below to learn about the unexpected side effects of eating too many grapes.

unexpected side effects of eating too many grapes [infographic]

Illustration: StyleCraze Design Team

Grapes are delicious fruits with a high antioxidant profile. The powerful plant compounds in grapes offer several health benefits. However, excess intake of grapes may cause side effects. These include an upset stomach, diarrhea, weight gain, complications during pregnancy, choking in kids, and allergies. They may also aggravate kidney problems and interact with some drugs. Though they make a healthy addition to your diet, consume them in moderation to avoid any adverse reactions.

Frequently Asked Questions

Do grapes increase breast feed?

Jesse Feder, RDN, says, “Specific research on grapes and breastfeeding is limited. However, it has been shown that fruit consumption is essential to having healthy breast milk for the baby.”

Are grapes good for heart disease?

According to Jesse Feder, RDN, “Grapes can be a great addition to a healthy diet and are good for people with heart disease. They are rich in fiber and antioxidants, as well as specific compounds that are thought to reduce bad cholesterol. This can help people reduce their chances of having adverse effects from heart disease or prevent it altogether.”

How many grapes can you eat in a day?

About 32 grapes can be considered as one serving. Eating one serving is okay if you are already on a healthy diet and physically active. But otherwise, stick to 8 to 10 grapes a day.

Can you eat grapes at night?

Yes, you can. In fact, eating grapes at night might promote better sleep. Grapes contain melatonin, the sleep hormone (25).

Can I eat grapes on an empty stomach?

You may have them on an empty stomach. Grapes are rich in nutrients and antioxidants and low in glycemic index.

What happens if you eat grapes every day?

Grapes offer numerous health benefits due to their exceptional nutrient and antioxidant content. They may be beneficial to the eyes, heart, bones, and other organs. Just remember to limit yourself to eating no more than one cup of grapes per day.

What is better – green grapes or red grapes?

Red and green grapes are both excellent in their own ways. However, some types of red or black grapes contain more antioxidants than green grapes.

Are grapes a laxative?

Yes, grapes have long been used as a laxative food due to the type of insoluble fiber, antioxidants, and high water content they have.

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