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What to avoid with watermelon?

Watermelon is a delicious and refreshing fruit that is enjoyed by many during the warm summer months. However, there are some things to keep in mind when eating watermelon to avoid potential issues.

Seed Spitting

One of the classic pastimes associated with eating watermelon is seed spitting contests. While this can be a fun activity, especially for kids, it is generally not recommended for a few reasons:

  • Seed spitting can promote the spread of unwanted watermelon plants. Watermelon seeds that are spit can sprout if they land in soil or compost. This can lead to watermelon vines popping up where they are not wanted.
  • Spitting seeds is not very sanitary, especially with groups of people. It can spread germs through saliva.
  • Watermelon seeds are hard and can actually cause injury if spit with enough force and hit someone. There are reports of seed spitting leading to cuts or eye injuries when seeds hit people.

Instead of spitting seeds, it is better etiquette to politely spit them into a napkin or cup. Watermelon seed spitting contests are best avoided altogether.

Eating Seeds

While watermelon seeds are edible, most people prefer not to eat them for a few reasons:

  • The seeds can potentially crack teeth if bitten into. They have hard outer coatings and can damage dental work.
  • Swallowing whole seeds can cause intestinal issues like diarrhea, cramps, or blockages in some cases.
  • The seeds don’t offer much flavor and have a bitter, chalky taste that is unappealing to most people.

It’s recommended to spit out watermelon seeds while eating. But if you do consume a few accidentally, it likely won’t cause problems. Just don’t chomp down on large quantities of seeds.


It’s easy to get carried away eating watermelon because of its sweet, refreshing taste. However, overdoing it on watermelon can lead to some digestion issues:

  • Excessive fiber from watermelon rind can cause gas, bloating, and loose stools.
  • Too much watermelon can cause diarrhea due to its high water content.
  • The natural fruit sugars in watermelon may cause upset stomach if large amounts are eaten, especially by those with sensitivities.

Practicing portion control is key. Stick to around 2 cups cubed watermelon per sitting and be mindful of not oversnacking throughout the day.

Underripe Watermelon

Eating watermelon that is not yet ripe can cause some digestive discomfort. Underripe watermelon has:

  • Less sugar, making it more tart and sour.
  • More raffinose sugars that can ferment in the intestines and lead to gas and bloating.
  • A tougher rind that may be hard to digest.
  • Increased citrulline amino acids that may cause nausea in some people.

Always inspect watermelons for ripeness before purchasing. Ripe watermelons have a creamy yellow underside and make a hollow thump sound when tapped.

Food Safety

As with any fresh produce, proper handling of watermelon is important to avoid foodborne illness:

  • Wash watermelon before cutting to remove dirt and bacteria.
  • Discard cut watermelon after 2 hours unrefrigerated or 4 days refrigerated.
  • Keep watermelon chilled at all times at picnics or barbeques.
  • Avoid cross-contamination by keeping watermelon away from raw meats.

Monitor children and elderly while eating watermelon as larger pieces are a choking hazard. Take care when enjoying this summer treat!


Watermelon allergies are rare but can be serious for those who have them. Allergic reactions to watermelon may involve:

  • Itchy skin, hives, eczema flares
  • Swelling of the lips, face, tongue, and throat
  • Wheezing, trouble breathing
  • Abdominal pain, vomiting, diarrhea
  • Anaphylaxis in severe cases

Those with known watermelon allergies should avoid ingesting it. Speak to an allergist about diagnosis and management of watermelon allergy if suspected.

Medication Interactions

The citrulline in watermelon may potentially interact with certain medications including:

  • Antihypertensives – Watermelon may enhance their blood pressure lowering effects
  • Erectile dysfunction drugs – Watermelon may increase their absorption
  • Antibiotics – Watermelon may reduce absorption of some antibiotics if taken at same time
  • Blood thinners – High vitamin K in watermelon may impact their effectiveness

Speak with your pharmacist or doctor about potential watermelon interactions with any medications you take.

Pesticide Residues

The thick rind of watermelon helps protect the inner flesh from pesticide residues. However, trace amounts may still be present on the outer rind. To minimize exposure:

  • Wash watermelon thoroughly before cutting.
  • Cut off the rind and pink/white portions close to the fruit to remove pesticide residue.
  • Buy organic watermelons when possible.

Proper washing and peeling helps reduce any pesticide risks when eating conventional watermelons.

High Glycemic Index

Watermelon has a high glycemic index around 80. This means it can cause a sharp spike in blood sugar for those with diabetes or prediabetes. To mitigate this effect:

  • Consume watermelon alongside protein, fat, or fiber to slow absorption.
  • Stick to small serving sizes no larger than 1-2 cups.
  • Test blood sugar levels after eating to see your individual response.

Enjoy watermelon in moderation and pair it with other foods to maintain stable blood sugar.

Citrulline Content

Watermelon contains citrulline, an amino acid that may cause side effects at high doses including:

  • Upset stomach, diarrhea
  • Headaches
  • Low blood pressure
  • Flushing and dizziness

Consuming typical amounts is not a concern. But stick to 1-2 cups per day and avoid concentrated citrulline supplements to prevent excessive intake.


Watermelon contains some FODMAPs that may be problematic for people with IBS following a low FODMAP diet. Limit intake to 1/3 cup at a time when reintroducing watermelon.

Fructose Malabsorption

People with fructose malabsorption cannot properly absorb excessive fructose. Stick to small portions of watermelon and avoid overindulgence to prevent symptoms like gas, bloating, and diarrhea.

Kidney Stones

The oxalates and vitamin C in watermelon may contribute to kidney stone formation in prone individuals. Limit watermelon to a few small servings per week if you’ve had kidney stones.


Overeating watermelon can lead to water retention and bloating due to its high water content. Monitor portions and stop eating at the first signs of fullness.

High Potassium Levels

People with kidney disease or certain medications like ACE inhibitors should be mindful of potassium levels. Large intakes of watermelon could potentially lead to high potassium.


Watermelon is very safe and healthy in moderation. Avoid spitting seeds, overeating, underripe melons, and foodborne illness. Allergies, medications, and digestive disorders may mean extra precautions needed for some. With good hygiene and reasonable portions, watermelon can be enjoyed worry-free by most people.