Food Intolerance

Food intolerances affect your digestive system. People who suffer from an intolerance, or sensitivity, can’t break down certain foods. They develop gas, diarrhea and other problems. An intolerance or food sensitivity is inconvenient but not life-threatening.


What is food intolerance?

When you have a food intolerance, it means your digestive system has a hard time digesting (breaking down) a food. Another word for food intolerance is food sensitivity.

Food intolerance means your gut is sensitive to certain foods and can’t tolerate them. When you eat these foods, you may experience uncomfortable symptoms like gas, diarrhea and abdominal pain.


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What’s the difference between food intolerance and food allergies?

Food intolerance, or food sensitivity, is not the same thing as having a food allergy.

A food intolerance:

  • Affects your digestive system.
  • Occurs when your digestive system can’t break down certain foods.
  • Causes symptoms like an upset stomach that aren’t life-threatening.
  • Brings on symptoms within a few hours after eating as the food makes its way through the digestive tract.
  • May not cause symptoms if you eat just a small amount of a food.

A food allergy:

  • Affects the immune system.
  • Occurs when your immune system mistakes a protein or other ingredient in food as a threat. Your immune system releases antibodies (proteins) called immunoglobulin E (IgE) to fight the threat.
  • Causes an allergic reaction, such as hives and swelling, shortness of breath or wheezing.
  • Brings on symptoms within minutes of consuming even a small amount of an allergy-inducing food.
  • May cause a severe, life-threatening reaction called anaphylaxis. Without an epinephrine treatment, this reaction can be fatal.

What are the most common types of food intolerance?

Common food sensitivities include:

  • Lactose: People who are lactose intolerant don’t make enough lactase enzyme to break down lactose, a sugar found in milk and dairy products. This food intolerance is the most common.
  • Histamine: Histamines are naturally occurring chemicals in foods like cheese, pineapples, bananas, avocados and chocolate. Red wine and some white wines also have histamines. People who are histamine intolerant don’t make enough diamine oxidase enzyme to break down this chemical.
  • Gluten: Gluten is a protein in wheat, rye and barley. Gluten sensitivity isn’t the same as having celiac disease, a type of autoimmune disease. When you have celiac disease, gluten damages the small intestines. If you have a non-celiac gluten sensitivity, your body has a harder time digesting gluten.


Symptoms and Causes

What causes food intolerance?

People with food intolerances often don’t make enough of a particular enzyme that the digestive system needs to break down a certain food or ingredient. Experts aren’t sure why some people develop food intolerances.

Certain gastrointestinal conditions may make you more prone to food sensitivities. These conditions include:

What are the symptoms of a food intolerance?

Symptoms of a food intolerance include:


Diagnosis and Tests

How is a food intolerance diagnosed?

A hydrogen breath test can detect lactose intolerance. During this test, you drink a liquid that has lactose. Then you breathe into a balloon-like container every 30 minutes for a few hours. If you’re lactose intolerant, the undigested lactose will cause high levels of hydrogen in your breath. You may also develop symptoms from drinking the lactose solution.

There isn’t a test for gluten sensitivity or histamine intolerance. An allergy test can detect food allergies but not a food intolerance. Your healthcare provider may ask you to keep a food diary to track meals and symptoms.

You may also try an elimination diet to remove certain foods from your diet for two to six weeks. If symptoms go away during this time — and then return when you start eating the food again — you may have a food intolerance.

Management and Treatment

How is a food intolerance managed or treated?

You may need to change your diet to limit or eliminate problem foods. Many people with food intolerances find that consuming small amounts of food causes few symptoms if any. When symptoms occur, over-the-counter medicines like antacids or antidiarrheals can help.

People who are lactose intolerant can consume lactose-free milk and dairy products. You can also buy lactase enzymes at drugstores. You can take lactase pills before consuming dairy products or add lactase drops directly to milk to break down the lactose.

What are the complications of food intolerance?

People who are lactose intolerant may not get enough calcium and vitamin D if they completely cut out dairy products. You can take supplements or use over-the-counter lactase enzymes to consume dairy products without getting an upset stomach.

People who cut back on products with gluten may need to eat more fresh vegetables, fruit and gluten-free whole grains to make sure they get enough fiber and other nutrients such as B vitamins in their diets, which are important for health.

Outlook / Prognosis

What is the prognosis (outlook) for people who have a food intolerance?

Food intolerances tend to be lifelong. Most people can manage symptoms if they reduce or cut out foods that cause digestive problems. Food intolerance may be an inconvenience (and the symptoms unpleasant), but it isn’t a life-threatening problem like a food allergy.

Living With

When should I call the doctor?

You should call your healthcare provider if you experience:

What questions should I ask my doctor?

You may want to ask your healthcare provider:

  • What type of food intolerance do I have?
  • What foods or ingredients should I avoid?
  • Am I at risk for other problems?
  • Should I look out for signs of complications?

A note from Cleveland Clinic

A food intolerance can cause stomach upset and other digestive problems after you consume certain foods or drinks. Having a food intolerance isn’t the same as having a food allergy. Food allergies cause an immune system response that can be life-threatening. Most people with food intolerances can have small amounts of those foods without distressing symptoms. A food diary and elimination diet can help determine if you have a food intolerance.

Medically Reviewed

Last reviewed on 08/11/2021.

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