What Is a Sugar Intolerance?

There's a differences between a sugar allergy and intolerance

A woman adding sugar to her drink

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For many people, the process of consuming sugar doesn’t make them ill. But for others, some experts suggest they may be allergic to sugar, or, at a minimum, intolerant to it.

However, it should be noted that no sugar allergies have been medically documented, and symptoms related to sugar ingestion are likely due to issues with intolerance. For these people, eating sugar comes with a set of unpleasant and uncomfortable symptoms.

Sugar Intolerances vs. Allergies

In general, when you ingest food that you’re allergic to, your immune system identifies that substance as a foreign invader. Alarm bells go off in your immune system, and it reacts by producing antibodies called Immunoglobulin E, according to information from the American Academy of Allergy Asthma & Immunology (AAAAI). The antibodies travel to cells in the body and trigger an allergic reaction.

The AAAAI notes that having an allergic reaction to a specific food versus having an intolerance to it are very different. When you have an intolerance towards sugar, it may cause you to feel unwell, but the result is not likely to be life-threatening.

Food intolerance happens when you are unable to break down certain foods in your digestive system. This may be due to a few different factors, including enzyme deficiencies or sensitivities to specific chemicals or additives in the food.

Another big difference between an allergic reaction and intolerance is that a person with the intolerance may be able to consume small bits of a problematic food without a negative response.

Types of Foods That Can Cause Symptoms

It’s hard to escape sugar—it’s in a lot of the foods that you probably eat on a daily basis, with the obvious being foods like fruit, desserts, sodas, pastries, ice cream, and dairy products. But, you may not be aware that it's also an ingredient in many other favorite foods like sports drinks, cereals, bottled condiments, salad dressings, and more.

Sugar acts as one type of fuel source for the body’s cells, so it plays a significant role in providing your body with energy. Sugars are carbohydrates, and there are several forms of sugar, including:

  • Fructose, which is a naturally-occurring sugar found in fruits, high carbohydrate vegetables, and honey.
  • Glucose is a crucial source of energy for the body and requires insulin to utilize it.
  • Galactose, which is a sugar present in dairy products
  • Sucrose, also known as “table sugar,” is a combination of glucose and fructose, and it comes from plants like sugarcane and beets.
  • Lactose, a sugar found in dairy products, is comprised of glucose and galactose.
  • Maltose is formed when two glucose molecules are joined together, and it primarily occurs in grains like malt.
  • Xylose comes from wood or straw, and it undergoes an enzymatic process to convert it to the sugar substitute we know as xylitol.

Foods to Avoid

If you’re lactose intolerant, you’ll need to avoid dairy products like:

  • Yogurt
  • Ice cream
  • Cheese
  • Milk
  • Butter
  • Soups, sauces, or other food dishes made with cream
  • Pudding

If you know you have an adverse reaction to sugar but can’t pinpoint a source, you may need to avoid it altogether. Sugar-containing foods include, but aren’t limited to:

  • Sodas
  • Honey
  • Anything with sugar cane or cane juice
  • Fruit
  • Fruit juices
  • Condiments with added sugar
  • Salad dressings, marinades, pasta sauces, or barbeque sauces that contain sugar
  • Bread
  • Cereal
  • Granola bars
  • Fruit roll-ups
  • Nut milk and nut butter that is sweetened with sugar
  • Cakes, cookies, and other pastries
  • Candy
  • Jellies, jams, and preserves
  • Foods containing high fructose corn syrup
  • Molasses
  • Agave


The symptoms of sugar intolerance vary widely among people. Some of the common symptoms a person may experience in regards to food allergies, as presented by Australia's Department of Primary Industries, include:

  • Stomach cramps
  • Changes in bowel habits like diarrhea
  • Uncomfortable abdominal bloating
  • Gas
  • Nausea and vomiting
  • Headaches
  • Migraines
  • Congested nasal passages
  • Wheezing
  • Hives, swelling of the skin, or an itchy rash like eczema

Other symptoms that have been linked to sugar intolerances include:

  • A tingling or itchy sensation in the mouth
  • Fatigue
  • Abnormal swelling of the lips, tongue, throat, face, or other parts of the body
  • Difficulty breathing
  • Lightheadedness or Dizziness
  • Fainting episodes

In contrast, if a person were to encounter a severe allergic reaction to food, they may experience anaphylaxis, or a life-threatening response to exposure or consuming the food. Although not likely to occur with sugar, typical symptoms of anaphylaxis to other foods include:

  • A tightening or constriction of a person’s airway
  • A substantial decrease in blood pressure due to the onset of shock
  • A swelling or closing of the throat making breathing problematic
  • Loss of consciousness
  • A fast heart rate.


Many people can manage a sugar intolerance by changing their diet, avoiding sugar, or significantly reducing its intake.

To find out if sugar is bothersome, you may want to keep a food diary, so you can track the foods you eat and identify how they make you feel.

For example, if you note that each time you put ketchup on a hamburger, you feel ill, that may be a clue that your body’s not tolerating the sugar that’s present in the product. Another example is with dairy products. If, after you eat ice cream or drink a glass of milk, you experience an onslaught of digestive problems, that may be a predictor that you’re lactose intolerant.

When to Visit a Doctor

If you suspect you may be experiencing unusual symptoms when you eat sugar, consult with a doctor. The treatment for sugar intolerance will depend on the level of severity of your reaction, but your doctor can use a variety of testing measures to confirm a diagnosis. Also, your doctor may recommend you consult with a nutritionist to create a healthy diet plan around any limitations you may have.

It can feel daunting to have an intolerance to food like sugar. But bear in mind, you may tolerate some sugar substitutes, so you can still have great tasting meals and snacks—minus the food that’s causing you distress!

Food Allergies Doctor Discussion Guide

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