Sugar Intolerance or Sugar Allergy?

Scientists question whether a sugar allergy is real

Sugar intolerance describes difficulty digesting certain types of sugar and does not involve the immune system reaction that happens with an allergy. In some individuals, sugar can cause various symptoms, including digestive issues, migraines, hives, and wheezing. While these symptoms may feel allergy-like, keep in mind that certain types of sugar intolerance are common, but having a true sugar allergy is rare.

A woman adding sugar to her coffee
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Intolerance vs. Allergy

In general, when you first ingest a food that you’re allergic to, your body forms an antibody called immunoglobulin E (IgE). During the second exposure to that same allergen (even if it's weeks or years later), alarm bells go off in your immune system, and it reacts by binding the allergen to the pre-formed IgE on mast cells or basophils, triggering an allergic reaction.

By contrast, food intolerance occurs 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 an intolerance is that a person with the intolerance may be able to consume small bits of a problematic food without a negative response.

Although some studies have suggested that sugar allergies are possible, there has been no evidence of sugar-specific IgE in people who have experienced severe allergy-like attacks.

Types of Sugar

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 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 is a sugar present in dairy products.
  • 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.
  • Sucrose, also known as “table sugar,” is a combination of glucose and fructose, and it comes from plants like sugarcane and beets.
  • Xylose comes from wood or straw, and it undergoes an enzymatic process to convert it to the sugar substitute we know as xylitol.

Of the possible causes of sugar intolerance, fructose and lactose are considered the most likely culprits.

There is evidence that fructans, a carbohydrate composed of chains of fructose, may be the real cause of non-celiac gluten intolerance, given that they are found in high concentration in wheat and rye.

Sugar Intolerance Symptoms

The symptoms of sugar intolerance vary widely among people. Some of the common symptoms 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, a life-threatening response to exposure or consuming 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

Seek emergency medical care immediately if you have any symptoms of anaphylaxis.


Many people can manage a sugar intolerance by changing their diet, avoiding sugar, or significantly reducing its intake. To identify which types of sugar are problematic, you may want to keep a food diary so that 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 an indication that you’re lactose intolerant.

Foods to Avoid

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:

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

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

  • Butter
  • Cheese
  • Ice cream
  • Milk
  • Pudding
  • Cream-based soups, sauces, or other food dishes made with cream
  • Yogurt

When to See a Healthcare Provider

If you suspect you may be experiencing unusual symptoms when you eat sugar, consult with a healthcare provider. The treatment for sugar intolerance will depend on the level of severity of your reaction, but your healthcare provider can use a variety of testing measures to confirm a diagnosis.

Also, your healthcare provider may recommend you consult with a nutritionist to create a healthy diet plan around any limitations you may have.

Food Allergies Doctor Discussion Guide

Get our printable guide for your next healthcare provider's appointment to help you ask the right questions.

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A Word From Verywell

It can feel daunting to have an intolerance to 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.

Frequently Asked Questions

  • Am I allergic to sugar?

    Probably not. A true allergy to sugar is possible in theory but extremely rare. Some people experience allergy-like symptoms when consuming sugar. However, it is more likely a sugar intolerance than an allergy.

    In addition, eating too much sugar can weaken your immune system and worsen environmental allergies like pollen or dust.

  • What is sugar intolerance?

    Sugar intolerance is an umbrella term for difficulty digesting certain types of sugar, like lactose or fructose. People who are lactose intolerant lack an enzyme (lactase) to digest dairy.

    Fructose intolerance is also common. There is evidence that fructans, a carbohydrate composed of chains of fructose, can cause symptoms similar to celiac disease.

  • Is sugar intolerance the same as glucose intolerance?

    No. Sugar intolerance is a dietary intolerance to certain types of sugar. Glucose intolerance refers to metabolic disorders that result in higher than normal blood sugar levels.

  • How do you treat sugar intolerance?

    Diet and sometimes supplements. People who are intolerant to certain types of sugar should refrain from eating foods that contain that type of sugar. 

    For instance, people who are intolerant of fructose should avoid fruits, high carbohydrate vegetables, and honey. People who are intolerant of maltose need to avoid certain grains, like malt. 

    Lactose intolerance is typically treated with lactase enzymes that help to break down lactose and prevent uncomfortable digestive symptoms. 

4 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 & Immunology. Allergy/intolerance to sugar. May 7, 2019.

  2. Jung CG, Yang EM, Lee JH, Kim SH, Park HS, Shin YS. Coca-Cola allergy identified as fructose-induced anaphylaxis. J Allergy Clin Immunol Pract. 2018;6:1787-9. doi:10.1016/j.jaip.2018.02.003

  3. Latulippe ME, Skoog SM. Fructose malabsorption and intolerance: effects of fructose with and without simultaneous glucose ingestion. Crit Rev Food Sci Nutr. 2011;51(7):583-92. doi:10.1080/10408398.2011.566646

  4. Skodje GI, Sarna VK, Minelle IH, et al. Fructan, rather than gluten, induces symptoms in patients with self-reported non-celiac gluten sensitivity. Gastroenterology. 2018;154(3):529-39. doi:10.1053/j.gastro.2017.10.040

By Jenny Lelwica Buttaccio, OTR/L
Jenny Lelwica Buttaccio, OTR/L, is a licensed occupational therapist and advocate for patients with Lyme disease.