Why Does Pizza Give Me Diarrhea?

If eating pizza results in a hurried trip to the bathroom, it's important to discover the underlying issue causing your diarrhea. Episodes of diarrhea after eating pizza may be due to any one of a number of various health problems or from improper food preparation or contaminants. Addressing the cause of your stomach upsets can help bring relief from the embarrassing effects or know when you should seek medical advice.

Undercooked pizza may cause diarrhea (Image: grafvision/iStock/Getty Images)


Digestive upsets, including diarrhea, after eating pizza can be the result of a food allergy, an intolerance, gluten sensitivity or food poisoning.

Symptoms of Lactose Intolerance

When your body doesn't produce enough lactase — the enzyme that breaks down lactose from dairy products — you could have episodes of diarrhea after consuming the milk-based cheese on your pizza. According to the National Institute of Diabetes and Digestive and Kidney Disorders, symptoms of lactose intolerant can begin within a few hours after eating the dairy food and can include:

  • Bloating
  • Diarrhea
  • Gas
  • Nausea
  • Pain in your abdomen
  • Stomach "growling" or rumbling sounds
  • Vomiting

Allergy to Pizza Ingredients

If you're allergic to one or more ingredients in your favorite splurge food, eating it could cause mild to severe symptoms, including diarrhea, within minutes to several hours. Dairy, wheat and shellfish are a few of the common allergens that can be linked to ingredients found in pizza.

In addition to digestive disorders, signs of an allergy from your pizza may include:

  • Itchy skin, eczema, hives or redness around mouth or eyes
  • Nausea or vomiting
  • Stomach pain
  • Nasal congestion or a runny nose
  • Sneezing
  • Odd taste in mouth

If eating pizza causes your tongue to swell or if you have trouble swallowing, chest pains and difficulty breathing within a few minutes, these are signs of anaphylactic shock. Anaphylactic shock can be fatal if you don't get emergency treatment right away.

Gluten Sensitivity or Celiac Disease

If you suffer from a gluten-related disorder, which can include gluten sensitivity or celiac disease, eating pizza will cause intestinal symptoms including diarrhea. Celiac disease is a condition caused by damage to the small intestine when your immune system overreacts to gluten, which is a protein in wheat, barley, rye and in products made with these grains.

If you have celiac disease, continuing to eat gluten-containing foods, such as pizza, can lead to intestinal damage. Over time, the villi that absorb nutrients in your intestines may be destroyed, which can lead to malnutrition. In addition to suffering from indigestion or becoming constipated, unintentional weight loss could result if your system isn't absorbing nutrients properly.

Contamination From Improper Preparation

Improperly handled food can become contaminated and lead to foodborne illness. This can happen if the meat on your pizza wasn't cooked to the proper temperature or if your fully cooked pie was cut on a surface that came into contact with undercooked meat or other contaminated food.

Cooks who don't wash their hands thoroughly can taint your entree as well. Under unsanitary conditions, bacteria or parasites get into the pizza, causing diarrhea. If you have a foodborne illness, you might be unable to control your bowel movements, experience cramping in your abdominal region, or develop a fever.

If your symptoms of diarrhea last more than 2 days, are accompanied by fever and vomiting, or your stools are black and tarry, you should see your doctor right away.

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