When you or your child live with food allergies, you may find yourself always on the lookout. Not only are you watching out for foods that you know cause symptoms, but you may also be keeping an eye out for other potential allergens.

One thing many people wonder about when it comes to food allergies is sugar. If you've been having symptoms after eating sweet foods or foods with added sugar, here’s what you need to know.

1. Sugar Allergies Are Very Rare

Scientists don’t all agree on whether true allergies to sugar exist. Some experts say there are no studies showing a true sugar allergy. However, a case report from 2018 followed a woman who seemed to have an allergy to fructose, which is a type of sugar. This woman first showed signs of an allergy when she fainted after drinking a Coke. She also had symptoms after eating other sweet foods and drinking Coke in a research setting. Researchers found that her reaction was to fructose, not to other ingredients in the foods or drinks she was consuming.

It’s important to know that one case study alone doesn’t prove anything. This case is mentioned because it’s the only known instance where someone seemed to have an allergy to a kind of sugar. Although fructose was identified as causing the woman’s symptoms, it is believed that the way it caused those symptoms was different from how typical allergies work. This could mean that it can’t be considered a true allergy. However, it’s also possible that sugar allergies exist but work differently from other allergies. Because this is the only case that has ever been studied, we can’t know for sure. Keep an open mind when thinking about sugar allergies.

Sugar is a carbohydrate that comes in a variety of forms, including glucose, fructose, galactose, sucrose, lactose, and maltose. Someone with a sugar allergy may not respond the same way to every kind of sugar they encounter.

2. Many Sugar Allergies Are Actually Intolerances

Most of the symptoms people experience after eating or drinking sugar happen because they have an intolerance to it. The symptoms usually involve the stomach or the bowels and may include diarrhea, bloating, and more.

Intolerances happen when a person’s body doesn’t make (or doesn’t make enough of) the enzyme it needs to break down a certain type of sugar. The most common types of sugars in foods are maltose, lactose, and sucrose. Each one has its own enzyme in the gut. If there’s not enough of the enzyme to break down the sugar, a person might experience digestive issues when they consume it. An intolerance to sugar is not an immune system response like in food allergies. The most common cause of sugar intolerance is lactase deficiency.

Some sugar intolerances are inherited, while others develop as the gene that produces the enzyme ages and produces less over time.

3. People With Sugar Allergies May Experience a Number of Symptoms

Because there has been so little research on individuals with sugar allergies, it’s unclear which symptoms are most common. However, it’s likely that people who have true sugar allergies, not intolerances, will experience symptoms similar to those of other allergies. These include:

• Lip or face swelling
• Feeling nauseous
• Dizziness
• Itching or developing a rash (hives)
• Stomach pain
• Diarrhea
• An itchy or runny nose
• Sneezing
• Wheezing or trouble breathing

If the allergy is severe, a person might experience swelling in their mouth, lips, tongue, or throat. They may have trouble breathing and even lose consciousness. If this happens, it could be a life-threatening reaction called anaphylaxis, and you should call for emergency help right away.

4. Sugar Allergies Are Caused by an Immune System Reaction

Food allergies are caused by an immune system response. The immune system’s job is to defend your body. Most of the time, it acts to get rid of dangerous invaders such as bacteria, viruses, and parasites.

When you develop a food allergy, your immune system sees a specific food protein as a threat and becomes very sensitive to it. Any protein that triggers an allergic reaction is called an allergen.

The first time the immune system encounters a food it’s sensitive to and thinks is dangerous, white blood cells begin producing substances called antibodies. When you come into contact with the food allergen again, the antibodies trigger immune cells to release other chemicals that cause your allergy symptoms.

5. Artificial Sweeteners May Be Safe if You Have a Sugar Allergy

If you or your child has an allergy or an intolerance to certain sugars, you may need to keep them out of your diet as much as possible. This can be hard since some, like fructose, are present in almost all processed foods.

Because true sugar allergies are very rare, there is no standard recommendation for people who have them. However, those with sugar allergies might be able to consume sugar substitutes. These are most often used by people who want to limit the number of calories they consume, since sugar is high in calories.

Most of the time, sugar substitutes are safe when consumed in reasonable quantities. However, they’re not recommended for children under the age of 2 or for people with certain medical conditions. More research is needed to fully understand how safe these substitutes are and what the risks of consuming them might be. If you can’t have sugar, there might be a different option that works for you, if your doctor agrees.

6. Sugar May Be Connected To Other Food Allergies

While being allergic to sugar is rare, consuming a lot of sugar early in life may make a person more likely to experience other food allergies. One study looked at over 1,000 children. It compared the number of calories they consumed each day from drinking sugary beverages, then looked at how many had food allergy symptoms during their second year of life. In general, the more sugar they drank, the more likely they were to have food allergies.

This is only one study. To prove the connection between sugar and food allergies, other researchers need to do similar studies and get the same results. However, there may be some good reasons why parents might want to limit the amount of sugar their children consume, even if the children don’t have a sugar allergy.

7. Your Doctor Can Help You Live Well With a Sugar Allergy

If you think you or your child might have a sugar allergy, talk to your allergist, immunology expert, or another health care provider to get medical advice as soon as possible. They can perform allergy testing to help determine whether you're dealing with an allergy or an intolerance. Then, they can help you find the most appropriate treatment for you. They may prescribe medications to treat your condition or refer you to a registered dietitian who can help you reduce your sugar intake and avoid the sugars causing your symptoms.

Note that foods with high sugar levels may not be obvious. Things like fruit juice, cereal, pasta sauce, and protein bars often contain high levels of sugar. These are in addition to more obvious sources of sugar, like ice cream, cakes, cookies, and other sweets.

Talk With Others Who Understand

MyFoodAllergyTeam is the social network for people with food allergies and their loved ones. On MyFoodAllergyTeam, more than 41,000 members come together to ask questions, give advice, and share their stories with others who understand life with food allergies.

Do you have or suspect you have a sugar allergy? Share your experience in the comments below, or start a conversation by posting on your Activities page.