Symptoms of Food Intolerance

Intolerance to food can cause a number of uncomfortable symptoms like bloating, gas, and abdominal pain.

The symptoms of food intolerance may be similar to symptoms of other conditions like inflammatory bowel disease and celiac disease.

Learn more about the symptoms of food intolerance, potential complications, and when to see a healthcare provider.

Lactose intolerance

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Frequent symptoms

Intolerance to food can cause a variety of symptoms. These symptoms vary between individuals and may also depend on the amount of food eaten or the type of food eaten.

In some cases, eating only a small amount of a food may not cause symptoms, while eating a large amount of that same food can cause symptoms.

The most common symptoms of food intolerance are often related to the digestive system. They may also cause symptoms in the skin and joints.

Timing of Food Intolerant Symptoms

Symptoms of a food intolerance typically start half an hour after eating a food or drinking a beverage a person is intolerant to. However, some symptoms of intolerance may take up to 48 hours to appear.

Common symptoms of food intolerance include:

  • Diarrhea
  • Bloating
  • Abdominal pain
  • Constipation
  • Eczema
  • Pain in the joints

Certain forms of food intolerance can be quite common.

Up to 70% of the global population has lactose intolerance, which means they are unable to consume dairy or milk products without discomfort.

This can cause symptoms similar to those listed above, as well as flatulence.

Another common cause of food intolerance symptoms are naturally occurring chemicals found in food. This may include:

  • Glutamate, a type of amino acid that naturally occurs in protein
  • Salicylates, a kind of natural preservative that can be found in nuts, spices, and many fruits and vegetables
  • Amines, which are a chemical in foods that are fermented, ripened, or aging

Other Symptoms

Whilst gastrointestinal symptoms like bloating and stomach pain are the most common symptoms of food intolerance, other symptoms may also occur.

These may include:

  • Nausea
  • Vomiting
  • Acid reflux
  • Heartburn
  • Migraines
  • Headaches
  • Nervousness
  • Flushed skin
  • Fatigue
  • Hives
  • Irritability
  • Anemia


Unlike an allergy to food, in the majority of cases, a food intolerance will not cause serious or life-threatening symptoms.

Some people with a food intolerance may even be able to eat some small amounts of a food they are intolerant to without experiencing any problems.

However, in some cases, a food intolerance can cause complications. Lactose intolerance is one example of this.

People who are lactose intolerant find it difficult to digest dairy and milk products. But these products are an important source of nutrients. These include:

  • Calcium
  • Vitamin A
  • Vitamin B12
  • Vitamin D

These vitamins and minerals are important for developing and maintaining healthy bones.

Lactose, the sugar found in many milk and dairy products, also plays an important role in helping the body absorb other nutrients like zinc and magnesium.

People who are lactose intolerant may find it challenging to get the healthy amount of vitamins and minerals found in dairy products. This can lead to a number of complications. These include:

  • Unintended weight loss
  • Osteopenia: This is the stage before osteoporosis when the bone-mineral density of bones is low. This is reversible but, if not treated, may develop into osteoporosis.
  • Osteoporosis: This occurs when the bones become brittle and weak. This also raises the risk of fractures and breaking bones.
  • Malnutrition: This can occur when the food eaten isn't delivering the nutrients required for the body to function properly. This can cause people to feel tired, depressed, and other problems like wounds not healing well.

When to See a Healthcare Provider

The symptoms of food intolerance can be similar to a number of other conditions. These include:

As the symptoms can be similar, it is important to see a healthcare provider to determine exactly what is causing the symptoms. This may change the approach taken during treatment.

If symptoms are actually the result of something else like celiac disease, continuing to eat even small amounts of gluten can cause lasting damage to the body and lead to complications.

If you are experiencing symptoms that may be due to a food intolerance, your healthcare provider will be able to help rule out other conditions through tests. They may also refer you to a specialist.


A food intolerance can cause a variety of symptoms. These often include symptoms related to the gastrointestinal system like bloating, abdominal pain, constipation, diarrhea, and gas.

A food intolerance is not life-threatening like a food allergy but may cause complications in some cases. This may include malnutrition, weight loss, or issues with bone health.

A healthcare provider may advise following an elimination diet to determine what foods are causing the problem. This is considered the gold standard in identifying food intolerances.

A Word From Verywell

Dealing with a food intolerance can be uncomfortable and annoying. But if you are going through it, you are not alone. Food intolerances like lactose intolerance are more common than you might think. If you are experiencing symptoms that are uncomfortable, consider reaching out to a healthcare provider for help and guidance.

6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. American Academy of Allergy, Asthma and Immunology. Food intolerance versus food allergy.

  2. Children's Hospital of Philadelphia. Food intolerance.

  3. GI Society. Food allergy vs. intolerance: know the difference.

  4. National Institute of Diabetes and Kidney Diseases. Definition and facts for lactose intolerance.

  5. Harvard Medical School. Food allergy, intolerance, or sensitivity: what’s the difference, and why does it matter?

  6. Celiac Disease Foundation. What is celiac disease?