Is It Possible to Be Allergic to Sugar?

Have you ever had a painful stomach ache or felt lethargic after eating something sugary? Same. But could that mean you’re allergic to sugar, or is something else going on? In many cases, feeling crappy post-sweets is really just a “sugar hangover” that happens if you eat a ton of sugar. That sugar overload can cause your blood sugar to spike, then crash and burn. While it’s extremely rare to have a real sugar allergy, some people may be super sensitive to even a small amount of the sweet stuff.

“There are people who cannot tolerate high sugar intake,” Tanya Freirich, M.S., RDN, tells SELF. “Often, people will get a headache and other symptoms from the sugar ‘high’ and reactive ‘low.’” But that’s still not necessarily an allergy, which we’ll get to in a bit.

An important thing to remember when we talk about sugar intake is the difference between naturally occurring sugars and added sugars. Naturally occurring sugars would include those that are inherently part of the food and not added in during processing—like the sugar that’s naturally found in fruits, vegetables, and many dairy products. Added sugars, on the other hand, are any sugars that were put in during the manufacturing process—whether it’s honey, high-fructose corn syrup, or something else.

Why some people feel strange after eating sugar | The difference between a sugar allergy and sugar intolerance | How to know if you’re allergic to sugar | The main types of sugar involved in sugar intolerance | What to do if you think you’re having symptoms related to sugar

When sugar enters the body, it causes your blood glucose level to rise, which then prompts the pancreas to release insulin to help move that glucose from the bloodstream into the cells, according to the National Institute of Diabetes and Digestive and Kidney Diseases. A large release of insulin can also result in a sugar crash later on, which you may experience as a headache, nausea, or gastrointestinal upset, Lauren Harris-Pincus, M.S., RDN, author of The Everything Easy Pre-Diabetes Cookbook, tells SELF.

Some people may experience this more drastically than others, especially if they’re prone to high blood sugar, or hyperglycemia, which happens when there’s a buildup of excess glucose in the bloodstream. This is typically an issue for people with diabetes or prediabetes, but it’s possible to have these conditions and not even know it, so it’s worth knowing the symptoms to watch out for. Signs of high blood sugar include fatigue, increased thirst, frequent urination, headaches, and blurred vision, among others.

But it's also possible that you're having a reaction to the sugar itself, which can happen if you have an allergy or intolerance to certain ingredients.

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Everyone has certain foods that just don’t sit right with them, or that cause not-so-desirable symptoms like indigestion, painful bloating, or cramping. But that doesn’t necessarily mean you have a true allergy to that food or ingredient. And while some people use the terms interchangeably, a food allergy and a food intolerance are two different things.

A food allergy is a reaction that occurs when your immune system overreacts to a food protein, thinking that it’s a harmful substance. According to Food Allergy Research & Education (FARE), symptoms of a food allergy can range from mild to life-threatening and include:

• Hives
• Abdominal pain or cramping
• Diarrhea
• Sneezing
• Trouble breathing
• Anaphylaxis (a severe, life-threatening allergic reaction)

A food intolerance means that you have trouble digesting whatever that food is. In general, this causes digestive issues, and the symptoms are not as severe as those of a food allergy, per the Mayo Clinic.

There are a variety of reasons that you could be intolerant to a particular food. Sometimes it’s a result of your body not producing an enzyme necessary to break that food down (for example, if you’re lactose intolerant, you lack the enzyme lactase that’s needed to break down lactose, the sugar in milk). Other times it has to do with an underlying health condition, like irritable bowel syndrome (IBS), or even stress or anxiety, the Mayo Clinic says.

According to the American Academy of Allergy, Asthma, and Immunology, symptoms of a food intolerance include:

• intestinal gas;
• bloating;
• abdominal pain;
• diarrhea.

It’s easy to confuse an intolerance and an allergy because the symptoms can overlap (we’re looking at you, diarrhea and abdominal pain). But a major difference is that food intolerances are not the result of an immune system dysfunction. What’s more, people with food intolerances may be able to have a small amount of the food without any issues (or they can take something to help aid digestion), whereas with an allergy, you generally can’t have any of the food allergen.

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While an intolerance to a certain type of sugar is fairly common, it’s extremely rare to have a true allergy to sugar. In fact, there seems to just be one documented case of fructose-induced anaphylaxis, which was published in a 2018 letter to the editor in the Journal of Allergy and Clinical Immunology: In Practice¹.

That said, there have been some limited reports of people having allergic responses to sugar substitutes. As SELF previously reported, stevia and the sugar alcohol erythritol can cause sensitivity reactions, such as burning throat and coughing, in some people. The research on this is scarce, but one 2007 Allergy study² describes two cases of anaphylaxis in infants after they came into contact with stevioside, an extract from the stevia plant.

“A sugar allergy is so rare it’s almost nonexistent, but it would be verified by antibodies,” says Freirich. So if you think you’re having an allergic reaction to sugar or any other food, you should seek immediate treatment. Then your primary care provider or allergist can carry out allergy testing.

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People are usually intolerant to certain types of sugar rather than to all of them. The most common is an intolerance to lactose, a sugar found in milk and other dairy products. “This is due to an insufficient amount of the enzyme lactase, which we need to break down the disaccharide lactose into glucose and galactose for digestion,” says Harris-Pincus. (But remember, this isn’t the same thing as a milk allergy, which means your immune system has a response to the proteins in milk.)

When we don’t have enough lactase, the intact lactose can cause gas, bloating, pain, or diarrhea. These sugar-intolerance symptoms can also occur with maltose (primarily found in malt and other grains) or sucrose (commonly known as table sugar), all of which have corresponding enzymes needed to break them down, Harris-Pincus explains.

So what about glucose intolerance? Glucose is a simple sugar and an important carb-based energy source for the body. In processed foods, it’s usually bound to another simple sugar to form sucrose or lactose. When people refer to glucose intolerance, they’re typically talking about having a metabolic condition that leads to high blood glucose levels, like prediabetes or type 2 diabetes.

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Again, cases of an allergic reaction to sugar are incredibly rare, but they could happen. If you have an immediate reaction after eating something (your throat feels tight, you’re having trouble breathing, you break out in a skin rash, etc.), you should visit your doctor or the emergency room. In severe cases, an allergic reaction could progress to anaphylaxis if not addressed quickly. And if you’re unsure at this point whether or not you have this type of allergy (or whether it’s life-threatening or not), it’s safer to err on the side of caution.

In severe cases, you may be treated with epinephrine (a medication that can reverse anaphylaxis) and then possibly a steroid (such as cortisone) to reduce inflammation and get the reaction under control, FARE says. Epinephrine is generally harmless, so even if it’s unclear how severe your allergy is, it’s safe to use, FARE explains.

If your allergic reaction is milder, you may just need an antihistamine. From there, your doctor or an allergist/immunologist may want to conduct skin-prick tests to pinpoint the cause of the reaction and determine if sugar is indeed the culprit. If you are diagnosed with a severe sugar allergy, you will likely need to carry an epinephrine auto-injector (such as an EpiPen) with you in case of emergency.

But if you’re experiencing weird symptoms after eating sugar that don’t necessarily line up with an allergic reaction, it’s still worth checking in with a health care provider to see what’s up. You may be experiencing symptoms of high blood sugar, or you may have a food intolerance to look into.

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Sources:

1. Journal of Allergy and Clinical Immunology: In Practice: Coca-Cola allergy identified as fructose-induced anaphylaxis
2. Allergy: Anaphylaxis by stevioside in infants with atopic eczema

Related:

• 5 Dairy Allergy Symptoms You Shouldn’t Ignore, According to Doctors
• I Have Severe Food Allergies, and These Are the 3 Comments I’m So Sick of Hearing
• What It Could Mean If You Have Stomach Cramps After Eating