Allergy or Intolerance: How Can You Tell the Difference?

If you’ve had a reaction — upset stomach or diarrhea, for example — to a certain food, you may think you have an allergy. But it’s more than likely to be food intolerance.

The key is to understand the differences between intolerance and an allergy. That way, you’re better prepared to handle them.

While symptoms of allergy and intolerance may appear similar, one clear difference is how they affect your body. An allergy is mediated by the immune system and can affect multiple organs. However, digestive issues usually point to food intolerance, not an allergy.”

Signs of intolerance

You may hear people say a certain food “doesn’t agree” with them. So what does that mean? What types of things show up as intolerance for some people? Here’s a list of common culprits:

  • Foods and food additives
  • Medications, which can cause gastrointestinal upset, headaches and dizziness
  • Certain ingredients — such as lactose — in some foods may create symptoms like cramping, diarrhea or vomiting within a few hours. In some cases, these ingredients are added by manufacturers to make foods more colorful and tasty. These issues cause discomfort, but they’re likely not life-threatenin.
Allergic reactions are different

Allergy symptoms, on the other hand, are much more intense. And they may occur within 30 minutes or up to two hours later.

If you have an allergy to peanuts or soy, for instance, you may have a rapid, severe reaction — called anaphylaxis — to even a small amount. This can include a rash or hives; swelling of the lips, tongue or throat; and difficulty breathing or wheezing.

Other things that commonly cause an allergic reaction include:

  • Drugs, including penicillin and other antibiotics
  • Insect venom from a bee or wasp sting
  • Environmental factors such as pollen, mold, dust, cats and dogs can cause allergic symptoms such as rhinitis and asthma.
The family connection

“A common question from patients is whether an allergy is hereditary or developed over time. The short answer is both.”

There is a higher risk of environmental allergies and asthma in children if one or both parents also are allergic.

Allergies typically become apparent early in childhood, especially from foods like milk, nuts, eggs and soy. But sometimes food and other allergies can develop later in life.

Intolerance is sometimes genetic, but can develop over time. One common example is lactose intolerance: As you age, your body may produce less of the enzyme that helps digest lactose in dairy products

Diagnosing allergies and intolerance

Your doctor can help you find out whether you have an allergy or intolerance. He or she will help establish a plan to help control your symptoms.

Allergy skin-testing can identify your body’s reaction to allergens. A blood test can, however, more precisely and accurately pinpoint elevated levels of allergy antibodies that your immune system produces.

Determining the cause of a food intolerance is not an exact science. In some cases, you may lack the enzymes you need to digest proteins in food.

It may help to keep a food diary to record what you eat, when you have symptoms and what they are. If you notice that a food or ingredient consistently gives you discomfort, it’s likely intolerance.

Managing your reactions

Avoidance is the best prevention method for keeping most allergies and intolerances in check. In other words, steer clear of the substances that bother you.

At Suburban Diagnostics, we offer a comprehensive range of tests for allergy and food intolerance


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This article has been adapted from Cleaveland Clinic and is accessible at-